Torque Converter Research Articles

Multi-objective optimization design for the blade angles of hydraulic torque converter with adjustable pump

To improve the efficiency of a hydraulic torque converter with adjustable pump at low load and thus increase the operation scope of high efficiency, multi-objective optimization design is carried out for the blade angles by incorporating three-dimensional steady computational fluid dynamics numerical simulation, design of experiments, Kriging surrogate model and multi-objective genetic algorithm. The results show that the angle of blade trailing edge in first-stage stator is the main influencing factor of the efficiency of hydraulic torque converter with adjustable pump. All the peak efficiencies of hydraulic torque converter with adjustable pump at three openings of the pump are improved after optimization, and the increased extent increases with decreasing opening of the pump. The operation scope of high efficiency consequently increases from 2.46 to 2.67. Besides, the improvement for the efficiency of hydraulic torque converter with adjustable pump is achieved by increasing the efficiency of the pump. The increase of angle of blade trailing edge in first-stage stator and the decrease of angle of blade leading edge in second-stage turbine after optimization induce the positive angle of attack at the inlet of second-stage turbine, thus realizing the performance optimization of hydraulic torque converter with adjustable pump. This also explains the increased proportion of the torque of second-stage turbine at larger speed ratios after optimization and the fact that the angle of blade trailing edge in first-stage stator is the main influencing factor of the efficiency of hydraulic torque converter with adjustable pump. The established multi-objective optimization method provides a reference solution for the optimization design of blade angles and for the improvement of integrated efficiency of hydraulic torque converter.

Coupled GA-SA Optimization Algorithm and Application for Compressive Curved Damper Springs of Automotive Lockup Clutches

An efficient global optimization algorithm has been developed by combining GA (genetic algorithm) and SA (simulated annealing). It is observed that the coupled optimization algorithm can converge faster than each single algorithm. It is applied for the design optimization of damper coil springs that absorb the torsional impact and vibration imposed on the clutch of an automatic transmission. Additionally, an user friendly computer program is developed in order to design various types of torque converter damper springs automatically. Dynamic characteristics and torque capacity of damper springs varies according to a spring constant that depends on a wire diameter, a coil diameter, the number of turns, a coil length, etc. The torque variation according to the spring constant characteristics of a curved compressive coil spring is calculated and compared with that of a straight one using the coupled simulated annealing and genetic algorithm.

Performance improvement and flow field investigation in hydraulic torque converter based on a new design of segmented blades

Hydraulic torque converter is of lower efficiency in the powertrain, particularly at low speed ratio, which is crucial for vehicles due to its ability of torque multiplication. Therefore, torque converters should be taken into account with both higher start-up acceleration and transmission efficiency. Inspired by the fact that the multi-airfoils of the aircraft can improve the lift, a new design of segmented turbine blade in torque converter is presented to improve the transmission efficiency and start-up acceleration. To ensure reproducibility and popularization, the camber line and shape of blades are extracted to obtain the expression in the Cartesian coordinate system. A scale-resolving simulation setting, large eddy simulation with kinetic energy transport, and refined hexahedron meshes, which were verified by our studies, are applied to simulate the three-dimensional transient flow numerically. According to the results of computational fluid dynamics analysis, the new design eliminated the ultra-high vorticity of the near-wall boundary layer to reduce the flow loss, which further improves fuel economy. The pressure difference in the segmented turbine blade is significantly higher than that of the original model, causing the improvement of powertrain performance. As a result, the torque ratio and nominal torque increase by 6.7% and 7.7%, respectively, at stalling speed ratio; meanwhile, the maximum efficiency increases by 1.1%. This research, using a new design of segmented blades, has many advantages, such as high starting torque ratio, large adjusting range, and greater fuel economy, and shows great potential to apply in the manufacturing process.

Research on Core Module Design of NR Power System Based on Engine Parameters

This paper proposes the concept of constant power interval for turbocharged engines. Based on the analysis of the existing engine and torque converter matching, a new method for engine and torque converter matching is proposed. At the same time, the paper adopts the modular idea, and divides the loader into five modules: engine, hydraulic torque converter, gearbox and drive axle, complete machine and external environment, and establishes mathematical model and MATLAB/Simulink simulation model respectively. The MATLAB/Simulink simulation model of each module is connected to establish the loader powertrain simulation system, and the performance of the loader drive system under the conditions of shovel loading, forward lifting and full load retreat is analysed. It indicates that the loader’s power and economy cannot be satisfied at the same time, and the design should be focused. The experimental results show that the system has perfect functions and stable performance, which meets the needs of engine performance development test.

Optimization of the Impeller Geometry for an Automotive Torque Converter Using Response Surface Methodology and Desirability Function

Response surface methodology (RSM) based on desirability function approach (DFA) is applied to obtain an optimal design of the impeller geometry for an automotive torque converter. The relative importance of six design parameters including impeller blade number, blade thickness, bias angle, scroll angle, inlet angle and exit angle is investigated using orthogonal design approach. The impeller inlet angle, exit angle and bias angle are found to exert the greatest influence on the overall performance of a torque converter, with two flow area factors being considered, namely 17% and 20%. Then, RSM together with central composite design (CCD) method is used to in-depth evaluate the interaction effect of the three key parameters on converter performance. The results demonstrate that impeller exit angle has the strongest impact on peak efficiency, with larger angles yielding the most favorable results. The stall torque ratio maximization is attainable with the increase of impeller bias angle and inlet angle together with smaller exit angle. In the end, an optimized design for the impeller geometry is obtained with stall torque ratio and peak efficiency increased by 1.62% and 1.1%, respectively. The new optimization method can be used as a reference for performance enhancement in the design process of impeller geometry for an automotive torque converter.

Two power split path hydrodynamic drive train of the commercial tractor

The article presents hydromechanical drive trains with a differential link at the input and output. As a differential link, three-link differential mechanisms with mixed gears mesh are used. The possible schemes of two-path hydrodynamic drive trains are investigated. It is shown that the operation mode of a two-path hydromechanical drive train is possible when the turbine wheel of the torque converter rotates in the direction opposite to the impeller rotation. This factor is taken into account when choosing the characteristics of a two-path hydromechanical drive train. It has been established that for the most common two-path hydromechanical drive train scheme, the planetary gear set characteristic reduction increases its maximum efficiency, decreases the torque converter active diameter and increases the relative speed ratio of the three-link differential spider pinion. It is shown that a two-path hydromechanical drive train in comparison with a one-path drive train allows for using more efficiently the engine transforming property to change the torque when changing the output load on the engine, which is very important for commercial tractors operating under variable load conditions.

A Discussion on Generation Mechanism of Higher Harmonic Noise Due to Blade Rows Interaction in a Torque Converter

A Discussion on Generation Mechanism of Higher Harmonic Noise Due to Blade Rows Interaction in a Torque Converter

Research on the Shift Strategy for the Traction Vehicle with Automatic Transmission

Firstly, according to the working characteristic diagram of engine and hydraulic torque converter, the matching working point is found. On this basis, the theoretical model of gear shifting law is derived when the engine and the hydraulic torque converter work together by taking the acceleration of adjacent two gears equal as the shift point. Finally, the theoretical model is simulated, the shift pattern diagram of tractor automatic transmission is obtained and the shift pattern diagram is analyzed, and the results are of important reference value for further study of shift delay and other characteristics.

Vehicle’s transmission as a vibro-impact system

The article discusses a dynamic model of a dual-clutch transmission. The absence of a torque converter and the short duration of gear shifting (0.2 - 0.5 sec) in such transmissions allows to present the shifting process as impact interaction. As a result, the gear shift excites the oscillations of the gearbox output shaft. Thus, the transmission of the vehicle can be considered as a vibro-impact self-oscillating system.

Internal Flow Structure of Torque Converter Analyzed with Dynamic Mode Decomposition under Steady Driving Condition

Internal Flow Structure of Torque Converter Analyzed with Dynamic Mode Decomposition under Steady Driving Condition

Investigation on the Cavitation Characteristics of High Power-density Torque Converter

Investigation on the Cavitation Characteristics of High Power-density Torque Converter

Analysis of the Internal Flow Structure of Torque Converter Using Proper Orthogonal Decomposition under Transient Driving Conditions

Analysis of the Internal Flow Structure of Torque Converter Using Proper Orthogonal Decomposition under Transient Driving Conditions

Three-dimensional optimal design of a cooled turbine considering the coolant-requirement change

Abstract Cooling technology is widely applied in modern turbines to protect the turbine blades, and extracting high-pressure cooling air from a compressor exerts a remarkable influence on the gas-turbine performance. However, the three-dimensional optimal design of a turbine in modern industrial practice is usually carried out by pursuing high component efficiency without considering possible changes in coolant requirement; hence, it may not exactly lead to improvement in the gas-turbine cycle efficiency. In this study, the turbine stator was twisted and leaned to achieve higher comprehensive efficiency, which is the cycle-based efficiency definition for a cooled turbine that considers both turbine aerodynamic performance and coolant requirement. First, the influence of twist and compound lean on turbine aerodynamic performance, considering stator-hub leakage, was investigated. Then, a method to predict the coolant requirement for turbines with different stator designs was applied, to evaluate coolant-requirement change at the design condition. The optimized turbines were finally compared to demonstrate the necessity of considering the coolant-requirement change in the optimal design. This indicated that proper twisting to open the throat area in the stator hub and compound lean to the pressure surface side could help improve the cooled-turbine comprehensive efficiency.

Slip at Vehicle Transmission System with Hydrokinetic Converter in the Urban Test Cycle

Abstract The study concentrated on slip phenomenon occurring at hydrokinetic converter in passenger car transmission system. Optimization of modern automatic transmission systems aims, on the one hand, to further increase the comfort of use, and on the other hand to improve the efficiency and reliability operation of individual components, in such a way as to ultimately result in lowering fuel consumption and also harmful emissions. One of the important factors affecting the mentioned transmissions properties as a whole system is the slip phenomenon occurring between the pump and the hydrokinetic converter turbine. The study presents the results of research on ZF 4HP20 and Fuji Hyper M6 gearboxes operating in vehicle transmission systems. The tests were carried out using the MAHA MSR 500 chassis dynamometer during driving at chosen test cycles. The research covered the transmission systems operating according to selected control algorithms affecting not only the gear shifting strategy but also the operation of the lock up clutch causing the transmissions slip values. As shown by the conducted research, the algorithm controlling the operation of the torque converter can have a significant influence on their operating indexes. The conducted analyses indicate the possibilities of improving the transmission operating indexes, especially in urban driving cycles.

Simulating Torque Converter on a 3 GTs Fishing Vessel using Computational Fluid Dynamics

Torque converter is needed to reduce the difference distance on an engine power curve and propeller operating load curve. Torque converter works by removing and cutting the flow of power from engine to transmission shaft automatically in order to adjust with fluctuative propeller load. Torque converter works on a fluid clutch principal hence it has ability to absorb and reduce excessive torque moments. This research aims to determine the effect of impeller distance against dynamic characteristics of torque converter on a 3 GT fishing vessel. Based on the designed torque converter dimension, a simulation using computational fluid dynamics (CFD) in an ANSYS 16.0 simulation software was conducted. The simulation was done on three distances between impellers i.e. 2.5 mm, 5 mm, and 7.5 mm and on five rotations i.e. 600 rpm, 1000 rpm, 1400 rpm, 1800 rpm, and 2200 rpm. Information obtained from the CFD simulation includes: pressure and shear stress distribution on impeller, flow velocity on the torque converter shell, torque value, as well as maximum transmission power of torque converter. The result shows that the ideal impeller gap for the 3 GTs fishing vessel from the dynamic characteristics parameter of torque converter is 7.5 mm.

Research Progress of Continuous Fiber Reinforced Ceramic Matrix Composite in Hot Section Components of Aero engine

Continuous fiber reinforced ceramic matrix composite (CFRC CMC) possessed low density, high temperature resistance, high strength and high toughness, which have been identified as a key and promising military material for replacing the traditional super alloy. CFRC CMC had been used in some hot section components, such as nozzle, combustor and turbine stator on M88-2, F100-PW-229, CFM56-5B, F-135, GEnx, LEAP-X and other aeroengines. Manufacturing technologies of CFRC CMC were thought as the commanding elevation for hot section components of aeroengines, and therefore much attention was given in Europe, America, Russia and other developed countries and regions. The evaluation and application of CFRC CMC were introduced in detail. Further, the challenge and tendency in the future were also put forward in this study.

Fundamental study on the optimal path of centrifugal pendulum vibration absorbers in automatic transmissions

In recent years, high-power and low-cylinder engines have seen increasingly widespread use. These engines produce a strong torsional vibration due to engine combustion. Furthermore, automatic transmissions necessitate the use of a lock-up clutch system that directly links the engine and gear train when the engine rotational speed is low. Using a torsional spring called a lock-up damper in the torque converter is not sufficient to absorb the torsional vibration. Therefore, the centrifugal pendulum vibration absorber (CPVA) has been developed to suppress the torsional vibration. The natural frequency of a CPVA is proportional to the engine rotational speed, and it is expected to suppress the torsional vibration over a wide range of speeds. However, the natural frequency of the CPVA varies because of the nonlinearity when the vibration amplitude of the CPVA is large. In this study, the optimal path of the CPVA to suppress the torsional vibration of the engine was investigated.

Numerical investigation about backflow of film cooling in static turbine blade leading edge

In this article, film cooling characteristics, especially the phenomenon of backflow for the straight turbine blade leading edge, are investigated. Shear stress transport k-ω turbulence model and structured grids are employed to assure the accuracy of the simulation, and the computational method is verified by the available experimental data. The influences of blow ratio, hole diameter, and the spacing between holes in each row are analyzed. The formation mechanism of backflow is discussed to prevent it from happening or relieve the degree of backflow, thereby to improve the cooling efficiency. The results showed that backflow can be avoided by adjusting the structure and the layout of film cooling holes. With increase in blow ratio, the cooling film becomes more obvious at first and then fades gradually for departing from the blade surface. The jet flow is influenced by the total pressure ratio between coolant cavity and surface of blade leading edge. Smaller film hole diameter and larger hole spacing makes it easier to eject coolant and form continuous film by slowing down the pressure in the cavity. Increasing ratio of hole spacing to hole diameter ( p/ d) can effectively prevent backflow, whereas larger p/ d also makes the film coverage area smaller.

A modal based reduction technique for wide loose interfaces and application to a turbine stator

Aim of this research is the prediction of the non-linear forced response of a stator bladed disk for aeronautical applications in the presence of friction contacts at the hook joints (casing – vane segment contact). Due to the large extension of the contact interfaces the use of classic node-to-node contact elements based on the Coulomb friction law becomes cumbersome. Although such approach appears convenient for problems involving small contact regions, it is computationally expensive when large contact interfaces with refined meshes are present between components. In this research, a novel modal interface reduction method is combined with a layer of Jenkins contact elements in order to efficiently predict the effects of friction on the non-linear forced response of the stator bladed disk. The wide rail/hook contact regions are therefore suitable for the application of the presented technique. The goodness of the proposed methodology is quantified both in terms of accuracy and time costs savings on the calculation of non-linear forced responses by exploiting cyclic symmetry hypotheses and the Harmonic Balance Method.

Assessment of structural behavior of torque converter dampener

A Torque Converter Dampener is a primary component for transmittal of power between the Engine and the Transmission. It comprises of three major components – driving cage plates, driven cage plates and set of springs. Being a spring based system, it provides a smooth conversion of torque from engine to the driveline. When the vehicle performs a gearshift, these springs damp the driveline oscillations and they get locked when the vehicle runs at a higher speed. A Torque Converter Dampener assembly is typically subjected to high torque and centrifugal loading and sometimes, there is a chance of breaking of the springs under operating loading conditions. This paper explains detailed method of analyzing Torque Converter Dampener using Finite Element Analysis. Cage plates and springs are modeled accurately with interactions and boundary conditions properly defined similar to actual hardware, in order to capture the physics of the system. As the problem is highly complex in nature, material non linearity, temperature effect and effect of dynamic fluid pressure are not taken into consideration. The analysis process takes care of the spring’s installation followed by applying centrifugal force and torque in alternating sequence. Similar method is repeated for different spring orientation to find out the worst case model and loading sequence. High stress locations on springs and Driving/Driven cage plates are identified and correlated with the actual hardware test results.