Braking Torque Research Articles

Real-time wheel-rail adhesion anti-skid control model for high-speed articulated trains on long downhill slopes during braking

To improve the braking efficiency of articulated trains on long-steep downhill gradients under different wheel-rail adhesion levels, this paper develops a real-time train braking control system equipped with an optimal adhesion anti-slip controller. Simulation validation is conducted under both dry and wet wheel-rail contact conditions with different braking torques applied on a steep downhill slope. The anti-slip adhesion control system comprises two modules: an adhesion optimization module using a forgetting factor recursive least squares (FFRLS) method to determine creep force function slopes for enhancing wheel-rail adhesion utilization, and a controller employing a neural network with a Levenberg–Marquardt (L-M) algorithm. Through the co-simulation of the train-track coupling dynamic model and the anti-skid control system, the real-time adjustment of the braking torque of the train can be quickly corrected. The results indicate that the anti-skid control system demonstrates excellent self-adjustment capabilities under various operating conditions. It effectively controls wheel slip, achieving optimal wheel-rail adhesion. This ensures the shortest possible braking distance while maintaining train stability and improving train transmission efficiency.

Numerical analysis of temperature behavior in solid and ventilated brake discs during repetitive braking

The braking system is one of the crucial systems in a vehicle, responsible for decelerating it to a lower speed or bringing it to a complete stop. During braking, the friction between the brake pads and the brake disc generates heat, most of which is absorbed by the brake disc rather than dissipated. Consequently, the brake disc can rapidly accumulate significant heat, especially during repeated cyclical braking, leading to high-temperature regions. Under these conditions, several negative effects, such as brake disc wear, cracking, and reduced braking torque, may occur. This paper aims to compare the thermal behavior of solid and ventilated brake discs under repeated cyclical braking. Numerical simulations were conducted using ANSYS software, revealing that the maximum temperatures on the solid and ventilated discs during the final braking cycle were 252.61 °C and 221.12 °C, respectively. Therefore, the maximum temperature on the ventilated disc is approximately 12.5% lower than on the solid disc. These findings demonstrate that ventilated discs are effective in demanding conditions, consistently ensuring a high level of safety.

A Review on Performance and Exhaust Emission Measurements of Methanol Fuel Blend in SI Engines

Global warming is mostly caused by the extensive use of conventional fuels, which release harmful gases into the atmosphere. It is therefore vital to develop renewable and sustainable fuels to fulfil worldwide energy demands while minimising environmental harm. Among the alternative fuels that have shown to be a viable fuel is Methanol (M). Emissions are decreased and performance significantly improves when M and its blends are utilised in Internal Combustion Engines (ICE). This article reviews and discusses M properties, its production process and varying M blends that affect performance and emissions from exhaust gases. The current paper focuses on Brake Power (BP), Brake Torque (BT), Vol Eff (Volumetric Efficiency), Brake Specific Fuel Consumption (BSFC) and BTHE and their impact on exhaust pollutants including Carbon Dioxide (CO2), Hydrocarbon (HC), Oxide of Nitrogen (NOx), and Carbon Monoxide (CO) which are currently a major concern. The pros and cons of using M as fuel for Spark Ignition (SI) engines are also covered in this article. Increased methanol fuel contains a blend that leads to improvements in the Vol. Eff, Cylinder Gas Pressure (CGP) and HRR. The percentage ratio of methanol fuel in a blend increases the Compression Ratio (CR) needed for ignition to occur.

Adaptive Second-Order Sliding Mode Wheel Slip Control for Electric Vehicles with In-Wheel Motors

The influence of the external environment can reduce the braking performance of the electric vehicle (EV) with in-wheel motors (IWM). In this paper, an adaptive sliding mode wheel slip control method with a vehicle speed observer consideration is proposed, which enables the EV to accurately track the optimal slip ratio in various environments and improve braking performance. First, the braking system dynamics model is established by taking the EV with IWM as the study object. Second, a super-twisting sliding mode observer is used to estimate the vehicle speed, and a new adaptive second-order sliding mode controller is constructed to control the braking torque. Finally, co-simulation experiments are performed under different conditions based on Carsim and MATLAB/Simulink, and the proposed scheme is validated by comparison with three control methods. The experimental results show that the proposed scheme has better control performance, and both the safety and control quality of the EV is improved.

Hydrogen-enriched lean-burn strategy for gasoline direct injection engine utilizing non-thermal plasma fuel reformer

The objective of the task is to sustain and enhance combustion stability at the extension of lean limit of customized Gasoline Direct Injection (GDI) Engine with the supplementation of Hydrogen Rich Gas (HRG) and hydrogen. HRG was supplemented from the on board non thermal Plasma Fuel Reformer (PFR) and hydrogen from the bottled storage through integrated gas control device to the GDI engine. The gas constituents of PFR was theoretically arrived from thermodynamic combustion equations to determine energy based fuel proportion in the ternary fuel injection system. Binary fuel mixture of HRG and hydrogen 10%, 18%, 30% of energy based proportion with gasoline were experimented on test engine. The impact of discrete and binary fuel mixture with gasoline at Stoichiometric Fuel Air ratio was observed and extended baseline equivalence ratio until misfire of the ternary fuel air mixture was occurred. Apart from significant improvement of performance the addition gaseous mixture increases oxides of nitrogen marginally. From the perspective it was noticed that combustion products exhibit better heat transfer out of cylinder at the Maximum Brake Torque Timing (MBT). This was attributed to higher combustion temperatures and improved quenching distances which in turn increased thermal efficiency against the specified equivalence ratio. However retarding MBT suppresses oxides of nitrogen and continued to increase thermal efficiency. It was concluded that lightning fast burn speed, fine fuel atomization of 10% mass based hydrogen and HRG 18%combination fraction increase engine thermal efficiency while decreasing NOx emission and alleviate HC trade-off characteristics.

Experimental assessment of catalytic biofuel effect on performance and exhaust emission of diesel engine

The present experiment is to analyze the effect of blended biodiesel of chicken fat CF10 (10% chicken fat and 90% diesel), waste cooking oil WC10 (10% waste cooking oil and 90% diesel), and combined chicken fat with waste cooking oil CF&WC10 (5% chicken fat + 5% waste cooking oil and 90% diesel) on the performance of diesel engine. The experiment is conducted at a constant compression ratio of 17, mixing 50 ppm alumina alfa (Al2O3-α) catalyst nanoparticles in each blend. The performance of biodiesel is analyzed at 25%, 50%, 75%, and 100% load conditions and is compared with pure diesel. The results show that the brake torque (BT) and brake power of CF&WC10 were found to be 22.48 Nm and 3.58 kW at full load conditions. However, the indicated thermal efficiency and BTE of CF&WC10 are at full loading conditions of 52.45% and 26.78% respectively. Because the supply of A/F ratio is 18.81, at full load condition and also lowering the brake specific fuel consumption up to 0.32 kg/kWh. Therefore, optimization of both performance and exhaust emission of an engine depends on BTE and NOx as well as HC emissions. Hence, from the emissions reduction point of view, CF&WC10 has lower emissions while achieving brake thermal efficiency similar to diesel fuel. The novelty of research shows CF&WC10 leads to enhanced performance of diesel engine compared to pure diesel fuel.

Design and optimization of squeeze-shear mode MR brake with multi-fluid flow channels based on multi-objective sooty tern optimization algorithm

Abstract Aiming at the deficiency of magnetic field utilization rate and the mass–torque ratio of magnetorheological fluid brake (MRB), a novel MRB is proposed in this paper. Initially, a squeeze-shear mode MRB with multi-fluid flow channels (S-MRB) is designed and its structure and working principle are described. Based on the analysis of the magnetic circuit, mathematical models are established to describe the rotary torque of the S-MRB. Furthermore, COMSOL software is carried out to model and simulate the electromagnetic field of the S-MRB, which verified the rationality of structure design. Then, with the braking torque and mass of the S-MRB as objective function, multi-objective optimization algorithm is adopted to optimize the structural parameters of the S-MRB. The optimization results show that the braking torque is increased by 25.34% and the mass of the MRB is decreased by 2.7%. Finally, a MRB braking performance test platform is established, and the effectiveness and superiority of the S-MRB are verified by braking torque dynamic response characteristic experiments.

Research on the characteristics of a pneumatic proportional valve

Abstract The execution of autonomous driving in heavy-duty trucks necessitates stringent regulation of their braking torque output. Hydraulic retarder serves as a widely auxiliary braking system in heavy-duty vehicles, with the pneumatic proportional valve functioning as the core component of its control system, regulating the output response and control precision of the braking torque of the hydraulic retarder. To improve the accuracy of brake torque control for hydraulic retarders, it is critical to conduct thorough research on the control system, especially the pneumatic proportional valve. Therefore, A detailed analysis of the working mechanism of pneumatic proportional valves was conducted, encompassing the construction of mathematical and simulation models. The efficacy of the simulation model was confirmed via experimental validation. When the control pressure increases, the simulation results are close to the experimental results, with a maximum discrepancy of 18%; when the control pressure decreases, the simulation results show a similar trend to the experimental results. The research can aid in formulating control methodologies for pneumatic proportional valves and offer theoretical guidelines for future exploration into boosting the precision of hydraulic retarder braking torque control.

Effect of temperature on braking performance of the comb-type disc magnetorheological brake

To investigate the effect of internal temperature variation of the comb-type disc magnetorheological brake on braking performance, firstly we simulate the temperature field analysis of magnetorheological brake by using the finite element method, and verify the reasonableness of the simulation using experiments. Secondly, the temperature variation of comb magnetorheological brakes during intermittent 5 min braking and continuous braking and the effect of temperature on the braking torque were investigated experimentally. The experimental results show that as the number of braking increases, the maximum temperature inside the brake increases until saturation, while the braking torque decreases. This research helps to enhance the realization of braking stability over the effective operating temperature range.

Comparative study on rolling resistance force in tire-ice interaction with a variation of tread rubber compound

Abstract The complex phenomenon involved in the tire-ice interaction can be better understood by studying the tire and ice properties. A significant force at the contact patch is the rolling resistance force. To study the effect of tire characteristics on rolling resistance forces, data collected from a free-rolling tire can be used as there is no tractive or braking torque applied to the wheel and thus the data representing the longitudinal forces is only related to resistive forces viz. friction and rolling resistance force. Although a lot of research and literature has been developed for tire-ice interaction over the years, there is a significant lack of work in the subsection of free-rolling tires specifically to study the effect of ice parameters on rolling resistance forces. To fulfill the aim of this study, several sets of experiments for 16 winter tires of 8 different rubber compounds in free-rolling conditions were conducted. The experimental data was compared with predictions of 4 well-known formulations from the literature. Based on the findings and the relative error between the predicted and measured values, it was proposed that the high error percentage could be due to the variation in the viscoelastic properties of the tread rubber. The longitudinal force generated during those tests would thus be a combination of frictional forces due to adhesion between the tread rubber and its viscoelastic nature in addition to the contribution from the remaining sections of the tire. The data collected from the experiments and results from implementing the existing models to obtain frictional force will further help in analyzing the relation between the rolling resistance force with variation in normal load, inflation pressure, and change in camber angle once a generic formulation considering the rubber compound effects is incorporated. Another significant finding of this work is that formulations in literature used for finding the rolling resistance coefficient of radial passenger car tires were found to highly underestimate the coefficient when compared to the equivalent coefficient of friction found from experimental results. The future scope may include the development of a model which will incorporate the viscoelastic properties, especially the loss moduli and loss tangent to evaluate the coefficient of friction and rolling resistance force in the free-rolling condition of a winter tire on ice as the rolling resistance losses are found to be highly correlated to these two properties.

Equal heat flux loading optimization approach for uniform wear of the wet brake

Due to their exceptional ability to endure heavy loads, cam-lobe radial-piston hydraulic motors are extensively utilized in heavy machinery. The wet brake is a key part capable of providing highly braking torque, which has numerous friction pairs and a compact structure. However, there exists a challenge in solving the issue of irrational pressure distribution which leads to non-uniform heat flux distribution and severe wear failure of the brake discs. For this, an innovative method to optimize the wet brake's loading structure has been developed to address the issue of non-uniform heat flux distribution. A thermomechanical coupling finite element (FE) model was established to establish a clear correlation between loading structure parameters and contact pressure distribution on the brake disc. An innovative equal heat flux criterion was introduced to guide the optimization process. Simulation results confirmed that the optimized loading structure achieved a brake disc contact pressure distribution aligned with the ideal heat flux density criteria. Experimental validation further demonstrated a notable reduction of up to 44.39 % in maximum wear depth (hmax) across different radii of the brake disc compared to the unoptimized structure. These findings underscore the efficacy of our approach in reducing wear rates and enhancing durability of the wet brakes.

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.

Structure optimization design approach of friction pairs for low-temperature rise wet brake in hydraulic motor

Cam-lobe radial-piston hydraulic motors are widely used in large heavy-duty machinery as direct-drive components of hydraulic systems. Due to their extremely high output torque and power density, the wet brake equipped with the hydraulic motors are necessary to achieve ultra-high braking torque in a compact space. However, due to a large number of internal friction pairs and small fit clearance between multiple friction pairs in wet brake, the rotation of the friction pairs in non-braking state will cause large friction torque loss and obvious temperature rise, thereby leading to the thermal failure of wet brake. How to optimize the structure of friction pairs to reduce the temperature rise of wet brake in non-braking state is a persistent challenge. Existing structure optimization design approaches of friction pairs in brakes mainly focus on the structure of each friction pair, which ignore the effect of fit clearance between the friction pairs on the temperature rise of brakes. Nevertheless, the fit clearance between friction pairs is an important factor that affect the temperature rise. For that, this study proposes a two-step structure optimization design approach of friction pairs for low-temperature rise wet brake in hydraculic motor, which simultaneously considers the fit clearance between the friction pairs and the structure of each friction pair. In this approach, the design process could be divided into two steps: firstly, the influence of fit clearance between multiple friction pairs on the temperature rise of wet brake in non-braking state is analyzed and optimized by the temperature rise theoretical model; secondly, in order to further reduce the temperature rise of wet brake, the oil groove structure of each friction plate are introduced and optimized by fluid-solid-thermal coupling simulation method. By this approach, the low-temperature rise structure of friction pairs with the optimized fit clearance between multiple friction pairs and oil grooves of each friction plate. Finally, a series of experiments are conducted to verify the effectiveness of the design approach. The result show that the temperature rise of wet brake could be effectively reduced 12 % by optimizing the structure of wet brake, demonstrating that the structure optimization design approach could provide a theoretical guidance to design low-temperature rise wet brake for large torque hydraulic motors.

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.

Investigating the Impact of Circular Sector Pole Head Structure on the Performance of a Multipole Magnetorheological Brake

The magnetorheological brake (MRB) epitomized a revolutionary modification in the braking systems because of its extremely efficient and well-controlled performance. To increase the safety and controllability of automotive braking system, researchers have developed a different MRB structures. Although much research on magnetorheological brakes has shown positive results in terms of brake torque, braking time, thermal efficiency, etc., the ability to increase braking force by expanding the disc surface, through which the magnetic field operates in a compact structure, is restricted. To address this issue, a new multipole MRB configuration with a unique pole head design that maintains compactness. Initially, the conceptual design was achieved by leveraging the combined impact of the twin disc-type structure and multipole concept. The model was used in a dynamic simulation to show how the braking torque of a magnetorheological braking system varies with coil current. The effects of circular sector pole head shape on braking performance were investigated using COMSOL Multiphysics software (version 5.5). A three-dimensional electromagnetic model of the proposed MRB was developed to examine the magnetic flux intensity and the impact of magnetic field dispersion on the proposed pole head structure of a magnetorheological brake. Based on simulation results, the circular sector pole head configuration is capable of increasing the active chaining regions for the MR fluid on the rotor surface, allowing for a more effective use of magnetic flux throughout the whole surface of a rotating brake disc, thereby increasing the magnetic field usage rate. The acquired simulation results show an increase in braking torque while keeping a compact and practical design structure.

Cooperative optimization of energy recovery and braking feel based on vehicle speed prediction under downshifting conditions

Regenerative braking can effectively recover vehicle kinetic energy, but its energy conversion efficiency is low under low-speed conditions, and there is also the problem of premature exit from energy recovery due to insufficient reverse electromotive force. The cooperation of gearbox gears can increase the speed range for the motor to recover energy, but unreasonable shifting will cause fluctuations in braking force and affect the consistency of the braking feel. Therefore, this paper aims to collaboratively optimize energy recovery and braking force fluctuations during gear shifting. Firstly, based on the model of braking system and transmission, the influence of shift strategy on braking impact and energy recovery is studied. In view of the challenge of determining a shift strategy with uncertain target braking speeds, a speed prediction model reconstructed by the support vector regression (SVR) model and the hybrid nonlinear autoregressive neural network (NAR) is proposed. On the basis of NAR-SVR speed prediction, the coupling effect of braking impact force and energy recovery efficiency is considered, and the collaborative optimization of regenerative braking torque and shift time is solved through a multi-objective cuckoo search algorithm. The hardware-in-the-loop test results verified that under high-speed conditions, the braking energy recovery rate of the proposed strategy was increased by 47.06 %, and the peak braking impact was reduced by 61.4 %. This research can provide a reference for the brake downshift optimization strategy and regenerative braking research of vehicles with non-decoupled electro-hydraulic composite braking systems.

Analysis of Combined Braking Torque on The Regenerative Anti-Lock Braking System in The Quarter Electric Vehicle Model

Analysis of Combined Braking Torque on The Regenerative Anti-Lock Braking System in The Quarter Electric Vehicle Model

Overvoltage Avoidance Control Strategy for Braking Process of Brushless DC Motor Drives with Small DC-Link Capacitance

Single-phase input rectifier brushless DC motor drives with a small film capacitor have many advantages, such as high power density and high reliability. However, when the motor system operates in regenerative braking mode, the dc-link capacitor with reduced capacitance may suffer from overvoltage without adding additional hardware circuits. At the same time, the braking torque control of the motor will be affected by speed variations. In order to ensure smooth and reliable operation of the motor system, an anti-overvoltage braking torque control method is proposed in this article. The relationship among the dc-link capacitance, the dc-link capacitor voltage, and the speed during regenerative braking is analyzed quantitatively, and the speed at which the regenerative braking is switched to the plug braking is obtained, which in turn consumes the capacitor energy to avoid dc-link overvoltage. Additionally, based on the relationship between the controllability of the braking torque and the speed, a reference value of the braking current that matches the speed is designed. The proposed method makes use of the capacitor’s energy storage during regenerative braking. Meanwhile, it mitigates the impact of motor speed on braking torque. Finally, the effectiveness of the proposed method is verified on a motor platform equipped with the dc-link film capacitor.

Influence of DC-Field Current on Short-Circuit Current in Variable Flux Reluctance Machine

DC-field windings of variable flux reluctance machine are wound on the same teeth with armature winding, which increases the short-circuit probability among the armature and field windings. Therefore, in this article, the various short-circuit faults of single phase, phase-to-phase, single field and phase-to-field are illustrated, and the influence of dc-field current on short-circuit current (SCC) and braking torque (BT) with consideration of initial rotor position are investigated. The SCC with dc-field current is analytically established, where the SCC and BT in transient and steady states are analyzed. The maximum SCC and BT are comprehensively compared by finite element method. It is found that the influence of dc-field current on the SCC and BT under transient conditions can be neglected. However, when the machine under un-saturated conditions, the SCC in steady states is associated with the saturation of iron core, i.e., the more saturated of the core excited by dc-field current in prefault, the smaller of the SSC in post fault. Both the SCC and BT are accompanied by the 12/14-pole VFRM prototype experimental verification.

Investigation of the friction and deformation behaviour of high-speed brakes

Spring-applied brakes are widely used components in industrial drive systems. They provide a braking torque by friction between a mostly organic friction lining and a metallic counter surface. Increasing with decreasing size, they currently achieve speeds of up to 6,000 rpm, which corresponds to a sliding speed in frictional contact of up to 35 m/s. At the same time, there is a trend towards high-speed drives, with speeds of 10,000 rpm and above. So far, little is known about the behaviour of the friction value and torque of conventional spring-applied brakes with low-cost organic friction linings under these operating conditions. For this reason, a test rig was develop - ed that allows testing at sliding speeds of up to 120 m/s with different load inertias. The tests carried out at KAt so far showed that with limited friction work, the conventional spring-applied brake reaches the nominal braking torque at higher sliding speeds. In addition to thermal overload of the friction lining, plastic deformation of the friction bodies can also permanently disrupt the operating behaviour of brakes operated at high sliding speeds. The plastic deformation of the friction discs manifests itself, for example, in a saucer-like shape of the discafs, leading to a reduction in the air gap and causing unwanted changes in the friction conditions. This paper describes the relationship between friction work and friction coefficient in organic linings and the physical mechanism of the deformation process of the friction discs. Based on these possible measures to reduce deformation are explained.