Torque Converter Research Articles

Multi-objective optimization of the cascade parameters of a torque converter based on CFD and a genetic algorithm

It is hard to simultaneously improve the peak efficiency (η *) and the width of the high-efficiency region ( Gη) for a hydrodynamic torque converter. A combination of comprehensive CFD simulation and multi-objective optimization was pretested. The elaborate CFD simulation calculation included a reasonable mesh layout, a robust algorithm and a correct turbulence model, whose results were also experimentally verified. In our study, the Kriging surrogate model was first used to construct a nonlinear relationship between the inlet and outlet angle and the economic performance index of the hydrodynamic torque converter. To ensure that the accuracy of the surrogate model meet the requirements, we also used 10 sets of sample points to verify the accuracy of our surrogate model. The accuracy is found to meet the requirements, which shows that the accuracy of the constructed surrogate model is relatively high. We choose to apply the second-generation non-dominant sorting genetic algorithm (NSGA-II) to solve our problem. After solving the Pareto frontier solution set, we obtain a set of global optimal solutions on the Pareto frontier solution set. The optimization results show that the η * is increased by 2.49% and that the Gη is increased by 14.23%. We extracted the flow field structure near the turbine region, characterized the difference between original and optimal model from the flow field perspective, and demonstrated the accuracy of our optimization results. Finally, we used CFD to verify our optimization results, further illustrating the accuracy of the optimization results prediction. Literature research indicates that a large amount of experiments to optimize the η * and the Gη of the hydrodynamic torque converter will bring huge trial cost and time cost. We conclude from our research that the proposed calculation method can solve such problems well.

Evolution of Emission Species in an Aero-Engine Turbine Stator

Future energy and transport scenarios will still rely on gas turbines for energy conversion and propulsion. Gas turbines will play a major role in energy transition and therefore gas turbine performance should be improved, and their pollutant emissions decreased. Consequently, designers must have accurate performance and emission prediction tools. Usually, pollutant emission prediction is limited to the combustion chamber as the composition at its outlet is considered to be “chemically frozen”. However, this assumption is not necessarily valid, especially with the increasing turbine inlet temperatures and operating pressures that benefit engine performance. In this work, Computational Fluid Dynamics (CFD) and Chemical Reactor Network (CRN) simulations were performed to analyse the progress of NOx and CO species through the high-pressure turbine stator. Simulations considering turbulence-chemistry interaction were performed and compared with the finite-rate chemistry approach. The results show that progression of some relevant reactions continues to take place within the turbine stator. For an estimated cruise condition, both NO and CO concentrations are predicted to increase along the stator, while for the take-off condition, NO increases and CO decreases within the stator vanes. Reaction rates and concentrations are correlated with the flow structure for the cruise condition, especially in the near-wall flow field and the blade wakes. However, at the higher operating pressure and temperature encountered during take-off, reactions seem to be dependent on the residence time rather than on the flow structures. The inclusion of turbulence-chemistry interaction significantly changes the results, while heat transfer on the blade walls is shown to have minor effects.

Influence of Circumferential Uneven Inlet Conditions on the Aerodynamic Performance of Turbine Stator

The application of the combination of rotating detonation combustor and turbine to propulsion system is a recent research focus. This paper verifies the feasibility of this combined propulsion method through numerical simulation, and the flow law and flow loss mechanism in the turbine stator passage under complex inlet conditions are obtained. The results show that the flow field in the turbine stator has serious circumferential unevenness. The interaction between the rotating pulsating wave and the blade is the main cause of flow loss.

Analysis of the Influence of the Number of Torque Converter Blades on Working Performance Based on the Response Surface Method

To understand the effect of the number of torque converter blades on the performance of torque converters, in this paper, we employed computational fluid dynamics and the response surface method to optimize the design of the torque converter. The number of pump blades, stator blades and turbine blades were used as design variables, and the torque transmission ratio and pump capacity factor were used as objective functions for multi-factor optimization design. The results show that the number of turbine blades had no significant impact on the converter’s performance, while the number of pump blades and stator blades had significant impact and showed strong correlation. Compared with the original torque converter, the optimized converter increased the starting torque ratio by 0.12 and the efficiency by 4%. It shows that the computational fluid dynamics and the response surface method can be combined to determine the optimal number of blades in the design of torque converters to reduce the cost and experiment time.

КИНЕМАТИКА МНОГОСТУПЕНЧАТЫХ СОГЛАСУЮЩИХ РЕДУКТОРОВ ДЛЯ ГИДРОТРАНСФОРМАТОРОВ

The study offers a design solution for online capacity adjustment of hydrodynamic torque converter powertrains. It is proposed to install a step-less speed drive or multistage matching gearbox between the engine and the torque converter to adjust the powertrain properties on the move depending on the current operating conditions. We propose the matching device arrange-ments. The solutions can be used in buses, trucks, tractors, diesel locomotives, etc. that operate in a wide range of external loads.

基于DOE的液力变矩器进出口角对性能的影响分析

基于DOE的液力变矩器进出口角对性能的影响分析

Bike clutch plate thermal analysis with using different materials

In this present paper, wet clutch is analysed by Computational Modeling. 2-D drawings are designed for multi plate clutch from computational calculations. 3D model is created in the Solid Edge modeling software for bike clutch. FEM analysis of clutch is carried out by varying friction materials with some non metals and composite materials. The best material suited for the lining of friction surfaces is found. Thermal transient investigation will be done on the wet grating plates to check the quality. Modeling of multi plate clutch is done by using Solid edge Software and then the model is imported into ANSYS Software for Structural, Thermal analysis to check the quality and temperature contours. Results show that friction materials like Al alloy, Al oxide, Cast iron, Carbon fiber and Al nitride generate 146.31 °C, 136.77 °C, 146.44 °C, 149.99 °C and 144.54 °C respectively. Heat flux results with the above friction materials are respectively 1.18 w/mm2, 1.04 w/mm2, 0.56 w/mm2, 0.0085 w/mm2 and 1.25 w/mm2. A twin grasp transmission is very like the traditional programmed, the primary distinction being the twofold grip structure contrasted with the single programmed grasp utilized in automatics. Automatics utilize a torque converter to move motor torque from the motor to the transmission. Basic investigation for grip plate has done utilizing the properties of three materials which are utilized for liner (for example carbon–carbon composites, Kevlar, Ceramic composites). A twin grasp transmission is very like the traditional programmed, the primary distinction being the twofold grip structure contrasted with the single programmed grasp utilized in automatics.

APPLICATION OF IMPACT THEORY TO ANALYSIS OF GEAR SHIFTS IN DUAL-CLUTCH TRANSMISSIONS

The article discusses a dynamic model of a transmission containing a dual-clutch gearbox. The absence of a torque converter in such gearboxes, taking into account the short duration of gear shifting (0.2 - 0.5 sec), allows us to present the gear shifting process as an impact. Gear shifting excites the output shaft of the gearbox. Thus, the transmission of the vehicle can beconsidered as a vibro-impact self-oscillating system.

Belt-Driven Integrated Starter and Generator Using Planetary Gears for Micro Hybrid Electric Vehicles

This paper presents a 12 V mechanical torque converting belt-driven integrated starter and generator (BSG) system without a DC-DC converter. A micro hybrid electric vehicle (micro HEV) typically uses a 12 V battery with a 12/48 V bidirectional DC-DC converter to satisfy its high starting torque and wide operating speed for generating the required power. In contrast, the proposed BSG consists of a wound field synchronous machine (WFSM), planetary gears, and a belt-type pulley, which does not require an additional bidirectional DC-DC converter. Owing to the mechanical torque converter, the proposed BSG system produces a high starting torque in starter-mode with a 12:1 gear ratio, and it operates in generator-mode with a 1:2 gear ratio to satisfy the required target specifications. To verify that the proposed BSG system meets the required target design specifications, simulations using MATLAB/Simulink 2018b and ANSYS electromagnetic 19.0 were performed. Additionally, the experimental results verify that this proposed BSG meets the required starter and generator modes specifications. Based on an analysis of the cost and vehicle environment conditions, the proposed BSG provides an efficient solution to the high cost issue incurred by a micro-HEV that requires a DC-DC converter system.

Upshift optimization control of dedicated hybrid transmission with P2 configuration

Based on the traditional automatic transmission, Dedicated Hybrid Transmission (DHT) with P2 configuration is developed by replacing hydraulic torque converter with a wet electronically controlled clutch and a driving motor. The paper proposed a coordinated control strategy of the upshift process for the P2 configuration parallel hybrid vehicle equipped with DHT to ensure the shift quality. Firstly, considering the meshing transmission loss, the dynamics modelling of DHT shifting process was built by Lagrange method, and the model parameters were identified by bench test; Secondly, taking no jerk as the constraint and minimum slipping work as the optimisation goal, the forward discrete dynamic programming was used to solve the optimal control law of the transmission torque of the shifting clutch and the input shaft torque of transmission. Besides, for the hybrid operation mode, further considering the influence of the motor, engine and main clutch, two coordinated control strategies of the main clutch engagement and slipping were proposed. The simulation results show that the two coordinated control strategies can achieve small jerk and slipping work, ensure smoothness in the course of gear shift. And by the method of slipping control of the main clutch, the shifting time can be shortened.

An experimental study of the integral characteristics of the intrachannel liquid film suction in a turbine stator blades cascade

This paper presents the results of an experimental study of the integral characteristics of the intrachannel liquid film suction in a flat cascade of turbine stator blades. Two slots for removing the liquid film from the interblade channel were arranged on the pressure surface of the stator blade. The experiments were carried out with initial steam wetness y 0 = 3 ÷ 9.5 % and theoretical Mach number downstream the cascade M lt = 0.6 ÷ 0.78. The operation mode of the moisture removal system was determined by the relative pressure drop on the moisture-removing slots and varied over a wide range. The investigations were carried out for both the operation of the moisture-removing slots one at a time and the combined suction of the liquid film simultaneously through both slots. The measurement system used in the experiments allowed separately determining the mass flow rates of steam and liquid removed from the interblade channel. The obtained integral characteristics served to evaluate the influence of various factors on the efficiency of the intrachannel moisture removal system. Based on the analysis of the research results, recommendations on the design and operation of intrachannel moisture removal systems have been formulated.

On-orbit evaluation of influence of magnetic-induced frequency shift on space borne atomic clock

The output frequency of an on-board atomic clock changes with a change in the external magnetic field as it is a magnetic sensitive device. In this paper, the phase comparison method is employed for the main and standby atomic clocks to evaluate the frequency stability of 10 Medium Earth Orbit (MEO for short) navigation satellite atomic clocks equipped with hydrogen atomic clocks. The average short-term stability is higher than 1×10−12 τ −1/2, and the daily stability is higher than 7×10−15. Based on this stability level, this paper presents a preliminary evaluation of the magnetic frequency shift in the atomic clock in the navigation satellite. The magnetorquer can cause a shift in the magnetic frequency of the atomic clock to an order of 1×10−13. In addition, the continuous operation of the magnetic torque converter for 1 h will cause the prediction error of the clock difference to be 0.4 ns. In this paper, the working state of the on-orbit magnetorquer is equivalent to the magnetic frequency shift noise, and its influence on the stability of the on-board atomic clock is simulated and analyzed. The simulation results show that the magnetic frequency shift noise worsens the long-term stability of the on-board atomic clock, especially for those with higher stability. Furthermore, the possible ways of minimizing the effect of the magnetic frequency shift on the atomic clock are discussed.

Analysis and Matching Calculation of Hydraulic Drive System of Tractor

Firstly, the matching principle of engine and hydraulic torque converter working together is introduced. Then, the mathematical model of matching input and output between tractor engine and hydraulic torque converter is established. The least square fitting method is adopted to fit the characteristic curves of tractor engine and hydraulic torque converter. The vehicle performance is evaluated by calculating the traction characteristics of the vehicle, which not only reduces the workload, but also improves the calculation accuracy

Design and Calculation of Hydraulic Transmission System of Loader

In order to give full play to the power of the engine, it is necessary to find the operating point of the engine and the hydraulic torque converter working together. This paper designs the hydraulic shift system of ZL50 loader with advanced mechanism theory. Firstly, the hydraulic variable speed system of the loader is designed according to the speed and maximum traction of the loader. Then, by calculating the traction characteristics of the loader and the heating of the drive system and evaluating its performance, it provides a reliable theoretical basis for the overall design of the loader.

자동 변속기 록업 클러치 댐퍼 스프링의 동하중 분석

The lock-up clutch of a torque converter is used to enhance the efficiency of the automatic transmission. It is composed of a circumferential friction surface and a torsional damper spring. A damper spring is shocked by the dynamic load transmitted from the engine output shaft and transmission input shaft. The causes of this dynamic load are the engine torque, shifting shock, and impact torque of the driving wheel. Engine shock or shifting shock can be predicted through a performance test. However, the impact of the driving wheel is unpredictable due to the random road conditions. In this study, typical dynamic loading conditions are considered in order to calculate the impact of the damper spring. Quantitative analysis shows that the impact of the driving wheel is 5.8 times that of the engine’s exciting torque.

Fast and Robust Hybrid Starter and Generator Speed Control for Improving Drivability of Parallel Hybrid Electric Vehicles

Speed control algorithms were studied to improve vehicle fuel economy and driving performance by rapidly combining two power sources—the engine and the driving motor. A hybrid starter and generator (HSG) was used in parallel hybrid vehicles, improving vehicle drive system efficiency by eliminating torque converters. The proposed zero-overshoot and zero-phase-error speed controller with active damping has the following three characteristics. First, it has an active damping structure resistant to load fluctuations (e.g., cranking torque fluctuation during engine starting). Second, there is no speed overshoot for the step command corresponding to the minimum engine running speed. Finally, it has no steady-state error for the ramp command generated by the moving vehicle. These control features reduce the time required to match the speeds of the two power sources, reducing delay when the vehicle starts and reducing energy consumption by minimizing unnecessary engine rotation. Simulation and vehicle test results proved that the proposed algorithm produced faster response characteristics and smaller steady-state errors than conventional control algorithms such as proportional-integral, integral-proportional, and two-degree-of-freedom algorithms. In this study, the fuel efficiency and driving performance of the hybrid vehicle could be improved by improving the performance of the speed control alone without any additional hardware changes.

On the enhancement of Savonius Bach-type rotor performance by studying the optimum stator configuration

The purpose of the present study is to enhance significantly the Savonius Bach-type rotor performance. This was achieved by adding a new stator around it. The stator is composed of three parts: shield, obstacle, and guide plate. A comprehensive parametric study was performed in which eight geometrical parameters for the stator were varied. One factor at a time method was utilized to find the stator optimum shape that achieves the maximum rotor power coefficient value. A 2D numerical model was employed using ANSYS Fluent 18.1. The dominant parameters that affect the aerodynamic performance of the turbine were demonstrated. According to the examined conditions, the results revealed that the maximum power coefficient for the rotor with optimum stator configuration achieved a value of 6 times greater than that of the bare rotor. It was concluded from this parametric study that the main effective element in the turbine stator is the stator obstacle. This study may be an important issue for further enhancement of the Savonius turbine's performance.

Effect of internal leakage on torque converter characteristics

To understand the effect of internal leakage on the torque field and characteristics of a torque converter (TC), a transient analysis was performed on the internal flow of a TC and the pressure pulsation characteristics of monitoring points in the convection channel. It was found that dividing the leakage area of the TC into a separate watershed improved simulation accuracy by 4%. When there was a leakage area, there were distinct collision, mixing, and assimilation stages between the leakage flow and the main flow. These phenomena caused energy loss that was highest at low speed ratios. However, the leakage flow always accounted for 12% of the main flow regardless of the speed ratio. At the same time, the leakage flow had a larger influence on pressure pulsation inside the TC and especially the low frequency band was more substantial. This shows that the leakage area has a large influence on the TC performance, energy loss, and flow state. Analysis of the leakage area showed that reducing the leakage area helps to improve powertrain performance and fuel economy.

A robust torque control approach for gear shift of a parallel hybrid electric vehicle with dual clutch transmission

This article proposes a robust control strategy for gear shifts of a parallel-type hybrid electric vehicle (HEV) equipped with a dry dual clutch transmission (DCT). A vehicle equipped with DCT requires accurate torque transfer control through the driveline during gear shifts to ensure good shift quality in the absence of smoothing effects from torque converter. Unlike conventional vehicles driven only by internal combustion engines, a HEV can utilize the drive motor to improve its gear shifting performances. In this article, an integrated torque and speed control strategy is developed to minimize the driveline oscillations that occur during gear shifts and to complete the shift as fast as the driver wants. A robust H-infinity controller is designed to control transmission output torque as well as clutch slip speed, particularly in inertia phase that mostly determines the total shift quality. The effectiveness of the proposed control strategy as well as its robustness is verified by comparative studies using a proven vehicle model developed in MATLAB/SimDriveline.

Fuel injection characteristic measurements under a transient injector driving condition using an injector driving algorithm

A new experimental system was developed to measure the cumulative injected fuel mass (CIFM) according to the driving time during the operation of a gasoline injector in an actual vehicle driving condition. An algorithm was developed to calculate the fuel injection timing and injection duration based on engine speed, crank position, and intake air mass data. The intake air mass and engine speed under the vehicle driving conditions were simulated using a computer. In this study, phase I of the FTP-75 mode was used as the vehicle driving mode. GT-Suite® was used as the computer simulation software. The engine part load data, an automatic transmission shift map, torque converter data and various vehicle specifications were used as input data for the GT-Suite® simulation. The computer simulation time interval is 0.05 seconds. An injector drive signal corresponding to the fuel injection amount and timing calculated by the developed algorithm was generated in a FPGA DAQ system. The drive signal from the FPGA DAQ is supplied to the base terminal of the transistor to switch the injector drive voltage source to control the fuel injection. The real-time measurement of the CIFM was done using load cells, dynamic strain amplifiers, and the FPGA DAQ system. The CIFM was measured at intervals of 0.05 seconds using an experimental apparatus developed when the vehicle was driven in the FTP-75 mode. A low-pass filter was used to remove the noise due to the impact force of the fuel jet on the load cell when measuring the CIFM. Twenty-eight repetitive measurements were conducted for an uncertainty analysis of the measurement data. A normal distribution was used as the error function. The deviation % distribution from the average CIFM value was evaluated at the 95 % confidence level. The deviation % from the average CIFM value was 3 % at 50 seconds after the start of phase I of the FTP-75 mode and converged to 0.2 % at 512 seconds.