Torque Efficiency Research Articles

Impact of Bioethanol Concentration in Gasoline on SI Engine Sustainability

This study presents an experimental investigation into the impact of blending bioethanol (E100) with conventional gasoline (E0), incrementally increasing biofuel levels up to E10, E50, and E70. The test was carried out in two stages: Stage I assessed the engine’s performance under fixed speeds (n = 2000 rpm and n = 2500 rpm) and fixed throttle positions (15%, 20%, and 25%) to measure changes in engine torque, efficiency, and environmental metrics by varying the concentration of bioethanol in the fuel. Stage II aimed to enrich the initial findings by conducting an additional test, running the engine at a fixed speed (n = 2000 rpm) and braking torque (MB = 80 Nm) and varying the ignition timing. Results indicated slight improvements in engine brake torque and thermal efficiency (up to 1.7%) with bioethanol content increased to 70%, and a notable reduction in incomplete combustion byproducts—carbon monoxide and hydrocarbons emissions (up 15% and 43%). Nitrogen oxide emissions were reduced by up to 23%, but carbon dioxide emissions decreased by a mere 1.1%. In order to increase thermal efficiency by adding higher bioethanol blend concentrations, adjusting the ignition timing to counter the longer ignition delay is necessary; however, higher emissions of nitrogen oxides and hydrocarbons are a major drawback of such a strategy. The results of the research are important in determining the optimal concentration of bioethanol in the mixture with gasoline for the energy and environmental sustainability of a spark ignition engine.

Self-assembly of Co/Pt stripes with current-induced domain wall motion towards 3D racetrack devices

Modification of the magnetic properties under the induced strain and curvature is a promising avenue to build three-dimensional magnetic devices, based on the domain wall motion. So far, most of the studies with 3D magnetic structures were performed in the helixes and nanowires, mainly with stationary domain walls. In this study, we demonstrate the impact of 3D geometry, strain and curvature on the current-induced domain wall motion and spin-orbital torque efficiency in the heterostructure, realized via a self-assembly rolling technique on a polymeric platform. We introduce a complete 3D memory unit with write, read and store functionality, all based on the field-free domain wall motion. Additionally, we conducted a comparative analysis between 2D and 3D structures, particularly addressing the influence of heat during the electric current pulse sequences. Finally, we demonstrated a remarkable increase of 30% in spin-torque efficiency in 3D configuration.

Estimation of the interfacial Dzyaloshinskii–Moriya interaction in all-metallic multilayer with perpendicular magnetic anisotropy

The interfacial Dzyaloshinskii–Moriya (iDMI) interaction which arises at the interface between a heavy metal (HM) and a ferromagnet (FM) can stabilize chiral Néel type domain walls in ultrathin perpendicularly magnetized multilayers. Dissimilar HMs are required on both bottom and top sides of the FM layer in order to introduce the structural inversion asymmetry which ensures an effective iDMI in the FM layer. HMs like Pt, Ir, Ta etc are very well known for developing large iDMI in the interface with Co, whereas noble metals like Au can produce negligible iDMI. Therefore, a multilayer Pt/Co/Au is chosen to determine the individual iDMI in the Pt/Co interface. Some procedures like field-induced domain wall motion study, spin–orbit torque efficiency estimation study are well established to quantify the effective field due to the iDMI ( HDMI ) which in turn gives the strength of the iDMI ( Deff ). Besides these procedures, a current-induced switching of magnetization was studied to construct a switching phase diagram where the critical current density of magnetization switching has been plotted as a function of the applied in-plane magnetic field. The experimentally constructed diagram and the simulated diagram using a micromagnetic study have revealed the possibility to quantify HDMI . Thus, a systematic and unified estimation of Deff has been done on all-metallic Ta/Pt/Co/Au multilayers.

Temperature-dependent magnon torque in SrIrO3/NiO/ferromagnetic multilayers

Magnetization switching driven by magnons is a promising technology capable of substantially decreasing energy dissipation and potential damage to spintronic devices. In this study, we investigated the temperature-dependent magnon torque effect in SrIrO3/NiO/ferromagnetic multilayers. It is found that the magnon-mediated damping-like spin–orbit torque (SOT) efficiency decreases with increasing temperature. Enhanced magnon transmission was observed in the vicinity of the blocking temperature of the NiO layer, which can be ascribed to the amplification of damping-like SOT efficiency by the spin fluctuations. More importantly, we have demonstrated that the magnon-mediated SOT is an effective method to manipulate a perpendicular magnetization, particularly using a critical switching current density that is pretty low, as evidenced by ∼ 4 × 105 A/cm2 for SrRuO3/NiO/SrIrO3 trilayers in this study. These findings suggest a promising avenue for the development of highly efficient spintronic devices operable through magnon currents.

Enhanced orbital torque efficiency in nonequilibrium Ru50Mo50(0001) alloy epitaxial thin films

Epitaxial thin films of fully nonequilibrium hcp-Ru50Mo50(0001) nanoalloys were prepared as a chemically disordered alloy, in which the intrinsic spin Hall effect is expected to be negligible. Structural analyses confirmed the epitaxial growth and atomic scale alloying of the films. In contrast to a tiny torque efficiency (ξDL) of ∼0.4% for Ru50Mo50/CoFeB, the ξDL for the Ru50Mo50/Ni heterostructure reached ∼30% with a long-range relaxation length. The apparent dependence of ξDL on the ferromagnetic layer can be attributed to the orbital Hall effect (OHE). Interestingly, a smaller ξDL was observed for Ru/Ni, suggesting that the nonequilibrium Ru50Mo50 enhances its OHE. Furthermore, the enhanced ξDL is maintained by inserting a Ru layer between the Ru50Mo50 and Ni layers, showing orbital transport through Ru. This finding illustrates potential applications of nonequilibrium nanoalloy films in spin orbitronics and contributes to getting insights into the understanding of the interrelationships between nanostructures and orbital transport properties.

Influence of exchange bias on spin torque ferromagnetic resonance for quantification of spin–orbit torque efficiency

Antiferromagnet (AFM)/ferromagnet (FM) heterostructure is a popular system for studying the spin–orbit torque (SOT) of AFMs. However, the interfacial exchange bias field induces that the magnetization in FM layer is noncollinear to the external magnetic field, namely the magnetic moment drag effect, which further influences the characteristic of SOT efficiency. In this work, we study the SOT efficiencies of IrMn/NiFe bilayers with strong interfacial exchange bias by using spin-torque ferromagnetic resonance (ST-FMR) method. A full analysis on the AFM/FM systems with exchange bias is performed, and the angular dependence of magnetization on external magnetic field is determined through the minimum rule of free energy. The ST-FMR results can be well fitted by this model. We obtained the relative accurate SOT efficiency ξ DL = 0.058 for the IrMn film. This work provides a useful method to analyze the angular dependence of ST-FMR results and facilitates the accurate measurement of SOT efficiency for the AFM/FM heterostructures with strong exchange bias.

Significant enhancement of spin-orbit torque efficiency by optimizing the interlayer thickness in [Pt/Ru]n/Pt multilayers

Spin–orbit torque (SOT) is a promising strategy for switching magnetization for magnetic random access memory and maintaining magnetization coherent precession for magnetic nano-oscillator or magnon-based logic device applications. Thus, the enhancement of SOT efficiency is the crucial point for the implementation of high-performance SOT devices. Here, we demonstrate that the effective damping-like SOT efficiency ξDL in the periodic [Pt(2 nm)/Ru(1 nm)]nPt(2 nm) multilayers with a low resistivity of ∼40 μΩ cm (comparable to 23 μΩ cm of the pure Pt film) exhibits an over 100% enhancement compared to that of the pure 12 nm thick Pt (ξDL = 0.055) at the periodic number n = 3, even reaches 0.257 (∼360% enhancement) determined by damping dc modulation method at [Pt/Ru] total thickness of 32 nm with n = 10. Our findings will benefit various SOT devices by significantly reducing energy consumption.

Design and Testing of a New Type of Planetary Traction Drive Bearing-Type Reducer

This paper presents the design and development of a new type of planetary traction drive bearing-type reducer. In this design, the transmission outer ring is replaced with an elastic ring. The design constructs a circular arc at the axial end of the rolling body’s contour line. This ensures that the contact point of this arc with the reducer’s outer ring and the inner ring’s axial end face is maintained on the radial traction contact line. As a result, it can replace the thrust bearing and provide an axial support function. It has the advantages of simple structure, easy processing, smooth transmission, and low noise. This paper first introduces the design and development process of this bearing-type reducer and presents systematic research on its transmission principle and dynamics. Subsequently, in response to the edge effect phenomenon of the outer ring contact line, the contour line of the outer ring is refined by adopting the shaping method used for bearing rollers, establishing a full circular arc profile shaping method, which significantly improves its edge effect. Finally, in our investigations, combined with experimental tests, a prototype of the bearing-type reducer was fabricated, and the speed ratio, torque, and transmission efficiency of the reducer were studied. The results demonstrate that the bearing-type reducer can achieve high transmission accuracy and efficiency. The transmission performance varies significantly under different lubrication conditions, with the peak efficiency reaching as high as 99.97% when using Santotrac 50 traction oil. The results verify the feasibility of the proposed design method and have the potential to be applied in wheel hub motors and robot joints.

Analytical Torque Ripple Reduction Strategy for Flux Modulated Doubly-Salient Reluctance Motor Drives Based on ZSC Harmonic Regulation

Compared to the conventional doubly-salient reluctance motor (DRM) drives, the novel flux modulated DRM (FMDRM) drives can achieve a better overall torque performance due to the dc-biased sinusoidal current excitation. However, previous investigations only focus on the dc-biased and fundamental current components, and the contributions of current harmonics to the torque production are not clear. This paper proposes an analytical torque ripple reduction strategy for open-winding FMDRM drives based on zero-sequence current (ZSC) harmonic regulation. Firstly, the contribution of third-order ZSC harmonic to the electromagnetic torque is investigated together with the dc-biased sinusoidal current components. Secondly, an alternative torque component cancellation method is put forward, where the additional third-order ZSC is utilized to counteract the dominating part of the alternative torque generated by the dc-biased sinusoidal current for torque ripple reduction. Both the amplitude and initial phase angle of the additional third-order ZSC are calculated by the analytical equation of electromagnetic torque. Moreover, the corresponding three-dimensional current distribution is investigated to achieve the desired ZSC regulation. With the proposed scheme, the torque ripple can be effectively suppressed while maintaining high output torque capability and efficiency. Furthermore, experimental results are presented on a three-phase FMDRM prototype to verify the proposed strategy. <fn fn-type="other" id="fn3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> </fn>

Surrogate-Based Multi-Objective Optimization of Flux-Focusing Halbach Coaxial Magnetic Gear

Due to their contact-free and low-maintenance features, magnetic gears (MGs) have been increasingly investigated to amplify the torque of electric motors in electric vehicles (EVs). In order to meet the requirements of propelling EVs, it is essential to design an MG with a high torque density. In this paper, a novel flux-focusing Halbach coaxial MG (FFH-CMG) is proposed, which combines the advantages of flux focusing and Halbach permanent magnet (PM) arrays. The proposed structure has a higher torque performance and greater efficiency than conventional structures. A multi-objective design optimization based on a surrogate model is implemented to achieve the maximum volumetric torque density (VTD), torque-per-PM volume (TPMV), and efficiency, as well as the minimum torque ripple, in the proposed FFH-CMG. The employed optimization approach has a higher accuracy and is less time-consuming compared to the conventional optimization methods based on direct finite-element analysis (FEA). The performance of the proposed FFH-CMG is then investigated through 2D-FEA. According to the simulation results, the optimized FFH-CMG can achieve a VTD of 411 kNm/m3, and a TPMV of 830 kNm/m3, which are significantly larger than those of the existing MGs and make the proposed FFH-CMG very suitable for EV applications.

The V-Angle and Rotor Ducts in Fluence on the Variable Reluctance Permanent Magnet Synchronous Machine on the Output Torque

Permanent magnet synchronous motors have risen to be a favour able choice for use in electric vehicles due to their high torque output and efficiency [9], whilst also being relatively lightweight in comparison to their asynchronous counterparts. It is of interest to investigate the parameters of the motor that can be optimized to further improve their efficiency, and in this paper, an analysis of the influence of altering the V angle and rotor ducts on the shaft torque which in turn influences the efficiency will be conducted. Though maximizing efficiency and shaft torque is the major focus of this study, it should be noted that other factors such as weight, cost and thermoregulation impact the choices made to apply the parameters used on the final product, but these findings aim to show how torque and efficiency can be maximized through running such simulations.

Optimal Design of a Surface Permanent Magnet Machine for Electric Power Steering Systems in Electric Vehicle Applications Using a Gaussian Process-Based Approach

The efficient design optimization of electric machines for electric power steering (EPS) applications poses challenges in meeting demanding performance criteria, including high power density, efficiency, and low vibration. Traditional optimization approaches often fail to find a global solution or suffer from excessive computation time. In response to the limitations of traditional approaches, this paper introduces a novel methodology by incorporating a Gaussian process-based adaptive sampling technique into a surrogate-assisted optimization process using a metaheuristic algorithm. Validation on a 72-slot/8-pole interior permanent magnet (IPM) machine demonstrates the superiority of the proposed approach, showcasing improved exploitation–exploration balance, faster convergence, and enhanced repeatability compared to conventional optimization methods. The proposed design process is then applied to two surface PM (SPM) machine configurations with 9-slot/6-pole and 12-slot/10-pole combinations for EPS applications. The results indicate that the 12-slot/10-pole SPM design surpasses the alternative design in torque density, efficiency, cogging torque, torque ripple, and manufacturability.

Enhanced spin Hall effect at high temperature in non-centrosymmetric silicide TaSi2 driven by Berry phase monopoles

We demonstrate the concept of Berry phase monopole engineering of the spin Hall effect in non-centrosymmetric silicide TaSi2. We show that while the effective damping-like spin–orbit torque (SOT) efficiency θDLeff of TaSi2 is nearly unchanged from 62 to 288 K (−0.049 to −0.069), θDLeff suddenly increases at high temperatures and becomes nearly double (−0.12) at 346 K. The corresponding intrinsic spin Hall conductivity σDLeff significantly increases at high temperatures, which can be attributed to the increasing contribution from the four degenerate points near the Fermi level via thermal excitation. Our results provide a strategy to enhance θDLeff at high temperatures via Berry phase monopole engineering and pave the way for SOT spintronic devices working at high temperatures.

Spin–orbit torques and magnetization switching in Gd/Fe multilayers generated by current injection in NiCu alloys

Light transition metals have recently emerged as a sustainable material class for efficient spin–charge interconversion. We report measurements of current-induced spin–orbit torques generated by Ni1−xCux alloys in perpendicularly magnetized ferrimagnetic Gd/Fe multilayers. We show that the spin–orbit torque efficiency of Ni1−xCux increases with the Ni/Cu atomic ratio, reaching values comparable to those of Pt for Ni55Cu45. Furthermore, we demonstrate magnetization switching of a 20-nm-thick Gd/Fe multilayer with a threshold current that decreases with increasing Ni concentration, similar to the spin–orbit torque efficiency. Our findings show that Ni1−xCux−based magnetic heterostructures allow for efficient control of the magnetization by electric currents.

Highly Energy-Efficient Spin Current Generation in SrIrO3 by Manipulating the Octahedral Rotation.

Materials with strong spin-orbit coupling (SOC) have been continuously attracting intensive attention due to their promising application in energy-efficient, high-density, and nonvolatile spintronic devices. Particularly, transition-metal perovskite oxides with strong SOC have been demonstrated to exhibit efficient charge-spin interconversion. In this study, we systematically investigated the impact of epitaxial strain on the spin-orbit torque (SOT) efficiency in the SrIrO3(SIO)/Ni81Fe19(Py) bilayer. The results reveal that the SOT efficiency is strongly related to the octahedral rotation around the in-plane axes of the single-crystal SIO. By modulating the epitaxial strain using different substrates, the SOT efficiency can be remarkably improved from 0.15 to 1.45. This 10-fold enhancement of SOT efficiency suggests that modulating the epitaxial strain is an efficient approach to control the SOT efficiency in complex oxide-based heterostructures. Our work may have the potential to advance the application of complex oxides in energy-efficient spintronic devices.

Spin-orbit torque efficiency enhancement to tungsten-based SOT-MTJs by interface modification with an ultrathin MgO

Spin-orbit torque efficiency enhancement to tungsten-based SOT-MTJs by interface modification with an ultrathin MgO

Enhanced current-induced magnetization switching via antiferromagnetic coupled interface in Co/Ho heterostructures

Rare-earth ferromagnetic (RE–FM) heterostructures have attracted significant attention due to their intricate spin structures and physical phenomena. The antiferromagnetic coupled (AFC) interface formed by the distinctive interaction between the FM and RE elements has critical contributions to the magnetization reversal process. In this work, we investigate the enhancement of current-induced magnetization switching with the AFC interface at the Co/Ho heterostructure. The results shows that an increased spin–orbit torque (SOT) efficiency of up to 250% was achieved at a Ho thickness of 7 nm, with a critical switching current density of 2.7 × 1010 A/m2. When a Cu interlayer was introduced between the Co/Ho interface, a decreased SOT efficiency was observed, indicating that the SOT enhancement is primarily attributed to the AFC interfacial effect. At the AFC interface, the interaction between Co and Ho atoms generates an additional torque, enhancing the effective SOT efficiency.

Smart optimization algorithms to enhance an axial turbine performance for wave energy conversion

One of the potential options for usage in wave energy conversion systems of the oscillating water column (OWC) type is the Wells turbine. Because of its relatively small output power and limited operating range, the cost of producing power increases, so the Wells turbine can only be used in a few ocean locations. Early deterioration of the turbine's performance resulted from the early turbine stall, which limits the power produced and the operating range because it does not operate in stall conditions. The current work aims to increase the Wells turbine's output power and operating range through a new turbine design. This design aims to integrate variable tip clearance design and casing groove design. A response surface optimization technique based on computational fluid dynamics (CFD) is used to determine the optimum dimensions of the new design. The present study utilized the toolbox for response surface optimization of the ANSYS software. Five geometrical parameters for the new turbine design were used as inputs for the optimization approach. At a flow coefficient of 0.250, the optimization technique sought to optimize the Wells turbine's torque coefficient (CT). The Wells turbine's average and maximum torque coefficients are improved by 39.13% and 74.32%, respectively. Compared to the typical design, the optimized design expands the operating range (OR) of the Wells turbine by 33.33%. The torque coefficient and efficiency of the enhanced Wells turbine increase by 82.97% and 71.64%, respectively, at a flow coefficient of 0.250. The torque coefficient modification factor of the enhanced Wells turbine is increased by 94.78% compared to the typical turbine. Based on a detailed flow analysis, the optimal new design reduces the axial flow velocities near the suction side on most of the blade span, which delays the flow's separation toward the trailing edge, which delays the inception of the enhanced turbine stall.

Design and Analysis of Mechanisms of 7-, 8- and 9-Speed Automatic Transmissions for Vehicle Powertrains

As the core device of engine-driven vehicle powertrains, the automatic transmission (AT) can obtain different output torques and speeds. Designing new mechanisms is the foundation for developing innovative ATs. This paper proposes an innovative design method for 7-speed, 8-speed and 9-speed AT mechanisms based on fractionated planetary gear trains (PGTs) and investigates the performance analysis of the AT mechanisms. Firstly, the detection of symmetric vertices in the PGT graph is studied, and a method for the topologic synthesis of 11-link 2-degree-of-freedom (DOF) fractionated PGTs is proposed. Secondly, the innovative design of 7-speed, 8-speed and 9-speed AT mechanisms is explored, leading to the discovery of two novel 7-speed AT mechanisms, three novel 8-speed AT mechanisms and four novel 9-speed AT mechanisms. Finally, the performance analyses of kinematics, torque, power flow and transmission efficiency of the AT mechanisms are conducted, and AMESim (Simcenter Amesim 2020.1) software is utilized to simulate speed ratios and transmission efficiencies of the AT mechanisms. The analysis and simulation results demonstrate that the nine novel AT mechanisms obtained in this study exhibit excellent overall performances. The speed ratios of each AT mechanism are reasonable, the step ratio is between 1.1 and 1.8, and the transmission efficiency exceeds 0.95. There is no cyclic power, or the cyclic power values are within an acceptable limit.

Torque Performance Enhancement for Hybrid PM Motor Considering Magnet Characteristic Difference and Variation

In this paper, for the hybrid permanent magnet (HPM) motor using multi PM materials as excitation sources, considering the characteristic difference and coupling effect between magnet materials, a preliminary design of the hybrid PMs is presented to improve the PM utilization and the superposition rate of torque components. Besides, according to the magnet characteristic variation under different operation conditions of the motor, a multi-objective variable condition weighted optimization design method is carried out to further improve the torque performance, efficiency and anti-demagnetization capability of HPM motor.