Maximum Braking Torque Research Articles

Optimization and performance verification of track vehicle multi-friction pair liquid-cooled full-disc brake system

Abstract The brake system is a crucial component for enhancing the reliability and maneuverability potential of tracked armored vehicles, with a particular emphasis on improving braking performance and reliability. This paper proposes a novel multi-friction pair liquid-cooled full-disc brake system by extending the friction pair and introducing a liquid-cooling structure. Simulation and experimental results demonstrate that the proposed solution significantly accelerates the heat dissipation rate of the full-disc brake system compared to its initial version. Moreover, the presented approach increases the maximum average braking torque by 24.7% and reduces the braking time by 15.2% compared to the original version of the brake system.

Analysis of braking performance and heat dissipation characteristics of multi-disc magnetorheological brake with an inner water-cooling mechanism

In order to improve the braking performance and reduce temperature rising of the magnetorheological (MR) brake during working condition, a multi-disc MR brake with an inner water-cooling mechanism is developed in this paper. The effective damping gaps are increased to eight sections by the four brake discs, which enhance the braking performance. An inner water-cooling mechanism is designed in the MR brake to improve the heat dissipation. The structure and working principle of the multi-disc MR brake are introduced, and the mathematical model of the braking torque and transient temperature field are established. The electromagnetic field simulation and the heat-flow coupling simulation are conducted by COMSOL software. A test rig is setup to investigate the braking performance and heat dissipation characteristics. The experimental results indicate the maximum braking torque can reach 96.24 N·m. Additionally, after 20 s of continuous braking, the temperature rise of the MR brake with cooling water input is lower than that without cooling water input. Compared with the braking torque reduction without cooling water input, the braking torque reduction with cooling water input is smaller. It is shown that cooling structures in the MR brake have a positive impact on improving braking performance.

Optimal design and experimental study of comb-type disc magnetorheological brake

The magnetic circuit method was adopted in this paper to design a comb-type disc magnetorheological brake for electric vehicles, aiming to solve the problem of the existing magnetorheological brake with large volume and limited braking torque. A mathematical model of braking torque was established. The effects of different structural dimensions on the performance of the brake were investigated through electromagnetic field simulation. The brake structure was optimized using PSO, which reduced the mass by 19.17 % and increased the torque by 6.58 %, and its performance was experimentally verified. The results showed that the brake produced a braking torque of 334 N·m at a saturated current of 3.6 A, with a response time ranging from 134 to 275 ms. After 10 braking cycles, the maximum braking torque remained above 94.5 % of the initial value. The source of heat was mainly located at the comb teeth portion of the brake disc.

Numerical investigation on the combustion performance of ammonia-hydrogen spark-ignition engine under various high compression ratios and different spark-ignition timings

This paper aims to numerically investigate the effects of high compression ratio (CR) on the performance of ammonia-hydrogen engines. In this work, four CRs from 10.7 to 13.7 with scanning spark timing (ST) from 28°CA to 0°CA BTDC were analyzed. The main results are as follows: As the CR increases, there is a trade-off relationship between the dissipation rate of turbulence and the turbulent kinetic energy (TKE). Initially, the TKE rises as the CR increases. As the CR continues to rise, the tendency for an increase in TKE diminishes, while the turbulent dissipation rate consistently rises. Additionally, there is an escalation in heat transfer loss. Therefore, there is a trend of rising and then falling in the flow velocity and turbulence intensity with the increase of the CR. Ammonia-hydrogen flame propagation is susceptible to temperature and flow field, and a high CR can improve ignition stability, shorten combustion duration, minimize cooling loss, and enhance output power. Unfortunately, the emission of NOx gradually rises as the CR increases. At high CR, the combustion performance is optimized by adjusting ST, and the maximum IMEP and ITE are 4 bar and 38.3 %, respectively. The ST for maximum braking torque (MBT) should be gradually delayed toward TDC as the CR increases.

A Diagnostic Machine Learning Algorithm for Air Brakes in Commercial Vehicles⁎

To safely introduce any level of autonomy to trucks, the health of their brake systems needs to be monitored continuously. Out-of-adjustment push rods and leakages in the air brake system are two major reasons for increased braking distances in trucks, and result in safety violations. Air leakages can occur due to small cracks or loose/improperly ft couplings which do not affect the overall braking capacity but contribute greatly to increasing the braking lag and reducing the maximum braking torque at the wheels. Similarly, an increased stroke of push rod leads to a larger delay in brake response and a smaller value of the brake torque at the wheels. Currently, the condition of an air brake system is inspected manually by measuring the push rod offset, checking the couplings and hoses of the system for air leakages. These inspections are highly labor intensive, subjective, time consuming and do not accurately quantify how adversely the braking system is affected. Having an on-board diagnostic device that can monitor the health of air brakes would be crucial in the prevention of road accidents, especially when considering any level of automation and comply with FMSCA safety requirements. The focus of this paper is to aid the development of such a diagnostic system that facilitates enforcement and pre-trip inspections and continuous on-board monitoring of trucks through the development of a model for its multi-chamber braking system; this model can be used to estimate the severity of leakage and the push rod stroke using real time brake pressure transients. A machine learning algorithm for estimating the air leakage in the air brake system and its experimental corroboration is presented in this paper.

Application of the Taguchi method to determine optimized parameters for designing brake of hand winch

Brakes are used to stop movement or adjust speed to ensure safety for mechanisms or machines. In this paper, the brake applied to hand winch will be studied. This hand winch has been studied by us in previous stages. However, the disadvantage of the winch is that the drum wall attached to the friction surfaces is not reasonable in terms of layout, as well as the parameters to optimize braking moment have not been calculated. A new brake structure is proposed in this study to solve the above problem. This structure does not use the drum wall as the friction surface. It does not affect the drum wall and it is easy to replace the friction surface when necessary. Instead, the cone brake is suitable for the structure brake and the size, structure, and design load. To determine the optimal parameters of the brake structure, the article will analyze the theory, and experiment design. The objective function is the maximum braking torque. Constraints are hand winch parameters, installation, friction surface material, and loading conditions. The corresponding factors are coded according to the Taguchi method, the orthogonal planning matrix is L18. Using Minitab software to analyze the Signal/Noise ratio, the study determined the optimal values for five factors including screw thread pitch, coefficient of friction (screw thread), cone angle, friction coefficient (brake), and large cone brake radius. Research results have selected the optimal parameters of the brake, and the optimal values have satisfied the constraints. The torque at the cone brake is greater than that of the disc brake approximately 37.7 %. The pressure at the friction surface is reduced by about 55 % compared to the disc brake surface

Study on Structure Design and Motion Characteristics of Pneumatic Flexible Wrist with Braking Function

A flexible pneumatic wrist with spatial position maintenance function is developed in this paper to settle the matter of insufficient flexibility of the robot wrist and self-braking technology. The wrist is made up of four artificial muscles and a pneumatic spherical brake in parallel, with 2 degrees of freedom. The wrist can realize multidirectional bending and adjust the wrist damping and braking in real time as required to achieve position maintenance. The theoretical model of the wrist bending angle is built based on torque balance. The variation of wrist bending angle and motion trajectory with air pressure is acquired through experiments. Simultaneously, the validity of the bending angle theoretical model is verified experimentally. A normally open pneumatic spherical brake is developed, and the mathematical model of braking torque is built and experimentally validated. Using a 3D dynamic capture system to compare the dynamic characteristics of the wrist under different excitation signals and different damping conditions. The experimental results reveal that the wrist has good flexibility and can achieve the functions of human hand pitch and yaw. The bending angle is 20.72° at 0.34 MPa. The pneumatic spherical brake has the function of spatial multidirection braking, and the braking force is adjustable. The maximum braking torque can reach 1.4 N m at 0.35 MPa.

Modeling to study the braking efficiency of the electric vehicle

Today, electric vehicles are produced and used a lot for the purpose of reducing environmental pollution. This paper presents the results of research on the braking efficiency of the electric vehicle MG ZS EV. The method of structural separation of the multi-body system is used to establish the braking dynamics model of the electric vehicle. The Newton-Euler equation is used to build the system of dynamics equations of the electric vehicle. Matlab-Simulink software is used to investigate the braking efficiency of the electric vehicle when running at different speeds. If a fully loaded electric vehicle MG ZS EV is running on type B road surface profile according to ISO 8608:2016 at V = [60,80,100]km/h and then braked with maximum braking torque, the braking acceleration of the electric vehicle is a = [6, 6.5, 7.5]m/s2, the yaw angle about the z-axis is ψ = [0.4, 0.7, 0.9]o, the electric vehicle is moving very stably and the braking efficiency of the electric vehicle meets the requirements of ECE-R13 standard.

A basic study on braking and regenerative braking torques for an axial gap type eddy current brake

Because of growing demand in the aircraft industry, research is being conducted around the world to reduce CO2 emissions by electrifying aircraft. The authors are studying a non-contact hybrid aircraft brake that combines an eddy current brake and a magnetorheological fluid brake. This paper presents a basic study of braking and regenerative torque using an axial gap type eddy current brake. The result as that a maximum braking torque of 51.3 mNm was obtained with a three-phase AC power supply when the speed of the conductor disc was 2,000 rpm, the current was 3 A, and the frequency was 10 Hz in the CW direction. The maximum regenerative torque was 48 mNm when the speed of the conductor disc was 2,000 rpm, the current was 3 A, and the frequency was 10 Hz in the CCW direction.

Research on Adaptive Distribution Control Strategy of Braking Force for Pure Electric Vehicles

The actual driving conditions of electric vehicles (EVs) are complex and changeable. Limited by road adhesion conditions, it is necessary to give priority to ensuring safety, taking into account the energy recovery ratio of the vehicle during braking to obtain better braking quality. In this work, an electric vehicle with an EHB (electro-hydraulic braking) system whose braking force adaptive distribution control strategy is studied. Firstly, the vehicle dynamics model, including seven degrees of freedom, tire, drive motor, main reducer, battery pack, and braking system, was constructed, which is attributed to the vehicle configuration and braking system scheme. Second, based on curve I and ECE regulations, the adaptive braking force distribution control strategy was formulated by taking the maximum regenerative braking torque as the inflection point, the synchronous adhesion coefficient as the desired point, and the battery SOC, road adhesion coefficient, and braking strength as the threshold. Finally, the vehicle dynamics simulation model was built on the Matlab/Simulink platform, and the simulation results verified the feasibility of the proposed braking force adaptive allocation control strategy. The research shows that the adaptive distribution control strategy can better adapt to the complex and variable driving conditions of the vehicle by combining the inflection point and the desired point. The braking energy recovery ratios of the vehicle under the NEDC and NYCC cycle conditions on a high adhesion road are 52.62% and 47.45%. The braking force distribution curve is close to curve I under the low adhesion extreme road.

Analysis of electromagnetic-thermal coupling braking properties of combined electromagnetic friction and shape memory alloy brake

To address the problems of severe heat generation and poor stability of traditional electromagnetic friction brakes, combined electromagnetic friction and shape memory alloy (SMA) braking method is proposed. This novel brake solves the traditional electric brake thermal decay problem based on the temperature sensing ability of SMA, which improves its working stability in a high-temperature environment. Based on Ampere’s law of magnetic field, the relationship between current and electromagnetic force was established, and the equation of electromagnetic force braking torque was derived. Based on the thermodynamic model of a SMA, the relationship between the frictional torque of SMA and parameters such as temperature, squeezing pressure, and structure size was established. The magnetic and thermal fields of this brake were analyzed by the finite element method to obtain the magnetic field distribution and the magnitude of electromagnetic force at different currents and to derive the temperature distribution of the brake at different currents. The brake was analyzed by the SMA squeezing pressure test platform and the braking performance test platform. The results show that the electromagnetic torque grows non-linearly with temperature, and the squeezing force generated by the SMA spring increases with temperature. When the current is 0.7 A, the braking torque generated by electromagnetism is 170.3 N m, while the maximum braking torque generated by the combination of electromagnetism and SMA is 212.6 N m, which is 20.4% higher than that of the traditional electromagnetic friction brake. This novel brake improves braking performance and ensures stable braking performance under temperature rise.

CFD-aided approach of modelling and dynamic characteristic optimization for a highly nonlinear auxiliary braking system

It is a considerable challenge to develop a mathematical method for modelling the coupling relationship between the control signal and braking performance in the design and optimization, especially with a highly nonlinear system. The present study thus establishes an integrated CFD-aided method, elaborately proposed based on a 1D/3D co-simulation to accomplish a goal of collaborative calculation between multi-physics fields, and conducting the braking and thermal properties that changes dynamically with the control signal. In particular, the 3D model is actually a multi-domain coupling CFD transient calculation, and the 1D model provides the dynamic boundary conditions. These results manifest some interesting issues, such as modelling the prediction interaction between the isolated control signal and dynamic braking capability. The synergies of the blade agitation and centrifugal force in the multi-phases development affect the oil-filling control and braking generation. The control pressure (Pair ) and throttle area (Aout ) are predominated in enhancing braking torque, shortening response time, and improving heat dissipation efficiency. The operations of Pair ≤ 3.2 bar and Aout ≥ 64π mm2 ensure a safe and reliable design and then optimize braking and control characteristics. The resulting maximum braking torque is 4070Nm, and the outlet oil temperature is reduced to 138°C.

Analysis of Slip rate Control Technology of Electric Vehicle Based on Sliding Mode Algorithm

With the increasingly prominent environmental and energy problems, it is very important to strengthen the research of new energy vehicles. In the research process of new energy vehicles, the safety of electric vehicles during driving is extremely important. In the braking process of electric vehicles, wheel slip control is an important factor to ensure the safety of electric vehicles. In the process of slip rate control, it is necessary to identify the wheel slip rate under different road surfaces, so as to complete the design of the slip rate controller on the basis of mastering the wheel friction characteristics. In this research, we mainly consider the maximum braking torque limit of motor output, scientifically distribute regenerative braking and hydraulic braking torque, complete the design of slip rate controller based on sliding mode algorithm, and introduce saturation function to solve the buffeting problem in road friction adaptive slip rate control method. Put forward the core of slip rate control strategy of electric vehicle. Through research, it is determined that the reasonable division of regenerative braking and mechanical braking based on slip rate can improve the safety of vehicle braking and ensure the efficiency of energy recovery. Therefore, in the process of electric vehicle slip rate control, the regenerative braking control method based on slip rate closed-loop control has application value.

Effect of different volume fractions of ammonia on the combustion and emission characteristics of the hydrogen-fueled engine

Hydrogen internal combustion engines (ICE) will play an important role in reducing carbon emissions, but low power density and abnormal combustion problems are the main obstacles restricting the promotion of hydrogen ICE. Ammonia is a low-reactivity renewable fuel. The purpose of this study is to study the effect of different ammonia-added volume fractions on hydrogen ICE. In this experimental study, the combustion and emission characteristics of an engine fueled by a hydrogen/ammonia mixture were evaluated at part-load operating conditions. The experiment was carried out on a modified engine, the engine speed was 1300 rpm, the absolute pressure of the manifold was 61 kPa, and the volume fraction of ammonia added was 5.2%, 7.96%, and 10.68%, respectively. The test results show that the addition of ammonia changes the combustion characteristics of hydrogen. As the volume fraction of ammonia added increases, the flame development period and flame propagation period are both prolonged, and the peak heat release rate decreases. The addition of ammonia increases the power of the engine and reduces the indicated thermal efficiency. At the ignition timing of the maximum braking torque, as the volume fraction of ammonia added increases, the indicated mean effective pressure and indicated thermal efficiency increase. Adding ammonia volume fraction has little effect on Nitrogen oxides (NOx) emissions, and NOx emissions gradually increase with the delay of ignition timing.

The Design and Magnetic Field Analysis of a Double Rotor Permanent Magnet Braking Device

During long-term continuous braking, high-intensity braking, or frequent braking, the temperature of the brake disc or brake drum will increase significantly, resulting in a decrease in the friction coefficient, the aggravation of the wear degree, and the dangerous heat recession of partial or even total loss of braking efficiency. This paper focuses on an innovative double rotor permanent magnet braking device, which is located on the inner side of the wheel hub, to improve the heat decay resistance of the friction braking device. The structure and principle of the double rotor permanent magnet braking device were given, and its main structural parameters were designed, calculated, and optimized. The geometric model and finite element model of the double rotor permanent magnet braking device were established. The static and transient magnetic field analysis and the braking torque characteristic analysis of the double rotor permanent magnet braking device were carried out by using Maxwell electromagnetic analysis software. The results show that the magnetic flux density in the working area of the double rotor permanent magnet braking device increases with the increase in rotation speed, the braking torque changes with the change of rotation speed, and the maximum braking torque occurs in the low-speed area, which is consistent with the theoretical calculation results. This provides a theoretical basis for the follow-up prototype test of the double rotor permanent magnet braking device.

Braking energy management strategy for electric vehicles based on working condition prediction

To improve the mileage capacity of electric vehicles (EVs), a dual-motor front-wheel-drive EV is considered as the research object. Through experiments with actual vehicles, data from four typical working conditions are collected; a C4.5 decision tree algorithm is developed to train a working condition recognition model. The long short termmemory neural network is used to train four deep-learning working condition prediction models, and the particleswarm algorithm is used to optimize their structural parameters. The braking strength, demand torque, and demand speed are determined based on the predicted working conditions. Based on four common braking energy recovery control strategies, front- and rear-wheel braking force distribution strategies are formulated according to the changes in braking strength. The maximum regenerative braking torque and remaining mechanical braking torque provided by the front wheels are optimized. The Seagull Optimization Algorithm is used to optimize the torque distribution of the dual motors on the front wheels and improve the working efficiency of the motors. In the experimental conditions, the recovered energy at 100 km is 2.6 kWh; the energy recovery rate is 19.1%, and the power consumption ratio is reduced by 15.8%, improving the EV cruising range.

Design and experimental evaluation a novel magneto-rheological brake with tooth shaped rotor

In this study, a novel magnetorheological brake (MRB) with tooth-shape rotor is developed. In this new MRB, traditional cylindrical rotor is replaced by a new one with tooth-shaped rotor. The teeth on the rotor act as multiple magnetic poles of the brake. Two magnetic coils are placed on side-housings of the brake to generate a mutual magnetic field of the MRB. The inner face of each side-housing has tooth shaped features as well. These tooth shaped features interact with the rotor teeth via magnetorheological fluid (MRF) medium. By using the tooth shaped rotor, more interface area between the rotor and the working MRF can be archived, which can improve performance characteristics of the proposed MRB such as compact size, low power consumption and high braking torque. After an introduction of state of the art of MRB development, the schematics and working principle of the MRB with tooth-shaped rotor is proposed. The modeling of the MRB is then derived based on magnetic finite element analysis and Bingham rheological model of MRF. Optimal design of the MRB considering mass and braking torque of the MRB is then conducted. From the optimal design result, it is shown that the mass and power consumption of the proposed MRB are significantly smaller than those of previously developed ones. In details, at high value of the maximum braking torque (100 Nm), the proposed MRB mass is only around 31.3% of the mass of the thin-wall single-coil and 42.6% of the mass of the thin-wall double coil MRB. In addition, at small values of the maximum braking torque (5 Nm), power consumption of the proposed MRB is only around 33% of that of the thin-wall single-coil and 45.5% of that of the thin-wall double coil MRB. Experimental works on prototypes of the proposed MRB are then performed for validation.

Development of a novel magnetorheological brake with zigzag magnetic flux path

In this research work, a novel disc-type configuration of magneto-rheological brake (MRB) with zigzag magnetic flux path is proposed. In this design, a rotor component consisting of several magnetic plates integrated in a disc made of non-magnetic material is implemented. A magnetic plate is separated with the others by nonmagnetic separators of the disc. Corresponding magnetic plates and separators are also implemented on the housing of the MRB. With this configuration, the magnetic flux line is forced to cross the MR fluid (MRF) duct from the disc to the housing at this separator and then from the housing to the disc at the next separator. This results in a zigzag magnetic flux path between the disc and the housing. The separators on each side of the housing are integrated on a bobbin, on which the magnetic coil is installed. When counter currents are applied to the coils on each side of the housing, a mutual magnetic field with zigzag flux lines across the MRF duct is generated. Based on the electromagnetic finite element and torque analysis, optimization problem considering the maximum achievable braking torque and the minimum mass of the MRB is performed. After that, optimal results of the MRB are obtained and compared with those of MRBs in previous works. Based on optimal results of the MRB with a maximum achievable braking torque of 20 Nm, an MRB prototype is fabricated and experimentally investigated to validate the simulation results.

Development of a novel MR clutch featuring tooth-shaped disc

In this research, we focus on development of a new configuration of magneto-rheological fluid (MRF) based clutch (MRC) featuring a tooth-shaped disc with multiple teeth acting as multiple magnetic poles of the clutch. The tooth-shaped disc is placed in a clutch housing composed of the left housing and the right housing. The inner face the housing also has tooth shaped features mating with the teeth of the disc through the working MRF. Excitation coils are placed directly on stationary winding cores placed on both side of the clutch housing. An air gap of 0.3 mm is left between the housing and the winding cores to ensure the housing can freely rotate against the winding cores. After the introductory part, configuration of the MRC is introduced and the transmitted torque of the MRC is derived. An optimization process to minimize the overall volume of the proposed clutch, which can generate a required maximum braking torque, is then conducted. The optimal results show that the overall volume of the proposed MRC is significantly reduced compared to a referenced conventional MRC (0.159 m3 vs. 0.295 m3). A prototype of the proposed MRC is fabricated for experimental works and good agreement between the experimental results and simulated ones is archived.

Intelligent optimization of EV comfort based on a cooperative braking system

To address the comfort of an electric vehicle, a coupling mechanism between mechanical friction braking and electric regenerative braking was studied. A cooperative braking system model was established, and comprehensive simulations and system optimizations were carried out. The performance of the cooperative braking system was analyzed. The distribution of the braking force was optimized by an intelligent method, and the distribution of a braking force logic diagram based on comfort was proposed. Using an intelligent algorithm, the braking force was distributed between the two braking systems and between the driving and driven axles. The experiment based on comfort was carried out. The results show that comfort after optimization is improved by 76.29% compared with that before optimization by comparing RMS value in the time domain. The reason is that the braking force distribution strategy based on the optimization takes into account the driver’s braking demand, the maximum braking torque of the motor, and the requirements of vehicle comfort, and makes full use of the braking torque of the motor. The error between simulation results and experimental results is 5.13%, which indicates that the braking force’s distribution strategy is feasible.