Torque Converter Research Articles

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.

The ultra-high efficiency gas turbine engine, UHEGT, part I: Design and numerical analysis of the multistage system

The Ultra-High Efficiency Gas Turbine Engine (UHEGT) was introduced in our previous studies. In UHEGT, the combustion process is no longer contained in isolation between the compressor and turbine. It is rather distributed in multiple stages and integrated within the high-pressure turbine stator rows. Compared to the current most advanced conventional gas turbines, UHEGT considerably improves the efficiency and output power of the engine while reducing its emissions and size. In this study, a six-stage UHEGT turbine with three stages of stator internal combustion is designed and analyzed. The design represents a single spool turboshaft system for power generation using gaseous fuels. The preliminary flow path for each turbine stage is designed by the meanline approach and modified using Computational Fluid Dynamics (CFD). Unsteady CFD calculation (via commercial software ANSYS CFX) is used to simulate and optimize the flow and combustion process through high-pressure turbine stages. The results show a base thermal efficiency of above 45% is achieved. It shows a successful integration of the multi-stage combustion process into the high-pressure turbine stages and a highly uniform temperature distribution at the inlet of each rotor row. High temperatures in some areas on the stator blade surfaces are controlled using indexing of fuel injectors and stator blades.

Thermo-mechanical simulation of ultrahigh temperature ceramic composites as alternative materials for gas turbine stator blades

The efficiency of the Bryton cycle strongly depends on the maximum temperature of the cycle. However, restrictions on metallurgical problems deprive engineers from the benefit of high temperatures. Ultrahigh temperature ceramics can be considered in such cases, instead of traditional materials like M152 superalloy. In this study, SiC reinforced HfB2 and ZrB2 ultrahigh temperature ceramics were proposed as gas turbine stator blades. The heat transfer and stress-strain equations were solved numerically by the finite element method to obtain temperature and stress distributions. The results showed that the maximum thermal stress occurs in vicinity of the cooling ducts where the temperature gradient is maximum. The maximum displacements of 1.2 mm (for HfB2–SiC) and 1.14 mm (for ZrB2–SiC) occur in the upper wall. It can be noticed that the ZrB2–SiC made blade showed lower maximum stress and displacement than those for the HfB2–SiC made one, as a result of lower expansion coefficient of ZrB2–SiC system. The addition of SiC to monolithic HfB2 and ZrB2 ceramics decreases their thermal conductivity and following that, the temperature uniformity in blades reduces. Although the thermal stresses and the probability of failure in these stator blades enhance, the ZrB2–SiC material presented the best performance among the other investigated samples. Both Coulomb-Mohr and Von Mises failure analyses were employed. It was understood that both blades made of HfB2–SiC and ZrB2–SiC composites simply withstand the applied stresses with the safety factors of about 1.5.

The static structural analysis of torque converter material for better performance by changing the stator angle

Torque converter is a commonly used machine device in automobiles to transmit the rotating power from a source like I.C engine, to a rotating driven load. It is widely used in automatic transmission vehicles to change the speed from the engine to the transmission and also multiply the torque. Effective modeling of torque converters leads to increase the performance and efficiency. The inlet and outlet blade angles take part in a significant role in determining the performance and efficiency of a torque converter. In this paper the performance of torque converter has been evaluated by changing the angle of stator blades by using ANSYS software. Four torque converter with different stator blade angle (15°, 25°, 35°, 40°) are designed and simulated to investigate the effects of blade angles on their overall performance and efficiency.

Failure analysis of turbine stator vanes of aero-engine

Failed stator vanes of various aero-engines were subjected to investigations. Stator segment designated as SV-1 failed due to impact by large iron containing object generated possibly inside the turbine. Damage on the vanes of stator segment termed as SV-2 has taken place by stress rupture at low stress and high temperature. Stator segment of another aero-engine termed as SV-3 is degraded by impact abrasion of iron containing particles. Investigation reveals that thermo-mechanical fatigue is responsible for large crack generation of stator vanes obtained from another aero-engine referred as SV-4. In contrast, multiple small cracks are formed because of creep fatigue interaction also known as thermal fatigue for impairment of another segment of the same aero-engine denoted as SV-5. Finally, measures to be taken for improving service life of these stator segments are discussed.

Efficiency improvement in thermal power plants using waste heat recovery of flue gas – simulation study.

In this paper an Organic Rankine cycle is used as waste heat recovery cycle for a 250 x 2 MW thermal power plant. The exhaust flue gas (80 to 130°C) in the thermal power plant is often released into the atmosphere as waste heat. This waste heat can be utilized as a form of heat source for the Organic Rankine Cycle. The treated flue gas form the Flue Gas Desulphurization plant will be fed to the heat exchanger where the heat transfer between the flue gas and the working fluid (e.g.: Ammonia, R245A) will take place. The working fluid will be fed to the (low pressure) turbine where the work done can obtained. After the expansion of the working fluid in the turbine, the working fluid is cooled in the condenser using water. Then this fluid is again sent to the heat exchanger using pump. The flue gas from the heat exchanger after the heat transfer will be then supplied to the stack. The cooling of the condenser water can be done using a cooling tower. As the load varies for the thermal power plant the temperature of the flue gas also changes and hence the turbine shaft output also changes this may result in tripping of the generator. In order to avoid this, a turbine governing system is designed with a step-up gear box and a torque converter. This governing system will keep the generating shaft in motion at constant speed even during low loads and high loads. This cycle will help the thermal power plants to obtain extra power output and will increase the efficiency of the plants.

An improved design of power-cycling hydrodynamic mechanical transmission

Recent studies have demonstrated that the power-cycling hydrodynamic mechanical (PCHM) transmission has excellent performance in improving power performance and fuel economy of a wheel loader. However, these results have been obtained by assuming that its speed ratio can always change continuously. Hence, this study first investigated the speed ratio of the transmission how to change when shifting from one gear to another. It was found that the concept of the PCHM transmission suggested in the literature is ineffective, even for a configuration with two gears in the gearbox. Then, the configuration of the PCHM transmission was developed as a different one to increase the torque multiplication capacity and efficiency of the transmission. A design method for this transmission is proposed to quantify its performances. The design method is based on a multi-objective optimization problem which is comprised of two objectives, seven design variables and eleven constraints. The relationships between average efficiency of the transmission and maximum tractive force of the vehicle and the seven transmission parameters are qualitatively examined. Results show that the performance of the transmission depends mainly on the number of transmission gears instead of on three parameters of the torque converter. The average efficiency is not sensitive to the maximum tractive force on a globally optimal Pareto front. The PCHM transmission with the new configuration can enable the average efficiency and the maximum tractive force to increase by 2.1 % and by 6.6 %, compared to that of the traditional hydrodynamic mechanical transmission, respectively.

A Study on the performance Restoration of Torque Converters for Passenger Car 6-Speed Automatic Transmissions with Remanufacturing Process Technology

We have developed a remanufacturing process technology that can restore the original performance of the toque converters for passenger car 6-speed automatic transmissions. The suitability of this remanufacturing process technology for performance restoration was verified by comparing the maximum performance efficiency values for three remanufactured torque converters and two original products. In the performance efficiency test, the maximum performance efficiency values of the remanufactured torque converters were 89.00 %, 88.98 %, and 88.51 %, respectively, with an average value of 88.83 %, and the maximum performance efficiency values for the original torque converters were 88.49 % and 88.32 %, respectively, with an average value of 88.41 %. As a result of comparing the maximum performance efficiency values of the remanufactured torque converters with those of the original torque converters, the average maximum efficiency value of the remanufactured products was 0.42 % points higher than that of the original products. Therefore, the suitability of the torque converter remanufacturing process technology developed through this study was verified, and it was found that the remanufactured torque converter was restored to the same or better performance than the original torque converter.

Optimum Design of Flexible Flywheels Used in the Powertrains of Automobiles

The flexible flywheel assembly used in the powertrain of an automatic-shifting automobile connects the engine crankshaft and the torque converter and provides a protection to potentially damaging axial movement between the crankshaft and the torque converter. In this research, a fully parameterized model of a flexible flywheel assembly is created, and then optimum design procedures with a zero-order optimization scheme are applied to investigate two cases: the first is to maximize a summation of modal frequencies of the structure; the second is to minimize the maximum equivalent stress in the model. Both optimum design cases have shown improvement in their objective functions, with one of the modes in the first case achieving the greatest improvement of +45.7%.

실차테스트를 통한 7단 자동변속기용 재제조 토크컨버터의 성능검증 방법에 관한 연구

실차테스트를 통한 7단 자동변속기용 재제조 토크컨버터의 성능검증 방법에 관한 연구

A Reverse-Engineering Method for Powertrain Parameters Characterization Applied to a P2 Plug-In Hybrid Electric Vehicle with Automatic Transmission

<div class="section abstract"><div class="htmlview paragraph">Over the next decade, CO2 legislation will be more demanding and the automotive industry has seen in vehicle electrification a possible solution. This has led to an increasing need for advanced powertrain systems and systematic model-based control approaches, along with additional complexity. This represents a serious challenge for all the OEMs. This paper describes a novel reverse engineering methodology developed to estimate relevant powertrain data required for fuel consumption-oriented hybrid electric vehicle (HEV) modelling. The estimated quantities include high-voltage battery internal resistance, electric motor and transmission efficiency, gearshift thresholds, torque converter performance diagrams, engine fuel consumption map and front/rear hydraulic brake torque distribution. This activity provides a list of dedicated experimental tests, to be carried out on road or on a chassis dynamometer, aiming at powertrain characterization thanks to a suitable post-processing algorithm. In this regard, the methodology was applied on a P2 Diesel Plug-in HEV equipped with a 9-speed AT. Voltage and current sensors are used to measure the electrical power exchanged between battery and electric motor; a torque sensor on the propeller shaft measures the total torque coming out from the automatic transmission. The hydraulic pressures in the four brake calipers are measured and CAN data is logged. The results of the testing campaign are then presented and discussed. Functional models of powertrain subsystems are introduced and their parameters estimated using least square method. The good match between models and experimental data proved that the proposed methodology, if properly adapted to the specific layout, is a suitable tool for powertrain parameter estimation.</div></div>

Parametric Analysis and Optimization of Leaning Angle in Torque Converters

Abstract Torque converters are durable fluid couplings that can provide output torque multiplication. Blade leaning angle represents the angular position of a blade chord with respect to its radial reference line, and it is an important blade variable regarding both hydrodynamic performance and manufacturability of a torque converter. In traditional design processes, blade leaning angles are often determined based on experiences of engineers; hence, this study proposed a design approach using the combination of computational fluid dynamics (CFD) and optimization. Two CFD models were developed to design blade leaning angles. A steady-state periodic CFD model was employed for the parameter study and the optimization, and a transient full three-dimensional (3D) model was performed to study the flow mechanism and evaluate the performance with higher accuracy. Design of experiment (DOE) technique was employed to investigate the relationship between blade leaning angles and hydrodynamic performance, and a reduced cubic model was derived from the results. It was found that blade leaning angles had profound effects on torque converter performance; a large blade leaning angle intensified the flow blockage effect, thus resulting in a lower mass flowrate and torque capacity. Seven torque converters with different blade leaning angles were tested to validate the obtained numerical results, and the test data were found to be in good agreement with the CFD predictions. Finally, the hydrodynamic performance of the base model torque converter was optimized by a multi-objective genetic algorithm.

Influence of Pump Rotation Speed on Hydrodynamic Performance and Stator Blade Surface Pressure Pulsation in Torque Converter

Abstract An experimental investigation was performed to characterize the influence of pump rotation speed on the hydrodynamic performance and the associated unsteady pressure on the stator blade pressure-surface in a torque converter. High-resolution miniature transducers were used to obtain the signature of the pressure pulsation at specific surface locations. Results show that the increase of the pump rotation speed can enhance the torque capacity of the stator, leading to a higher torque ratio in the low speed ratio range and an improvement of the highest transmission efficiency. The efficiency increase rate starts to reduce at approximately SR = 0.4, corresponding to where the stator capacity reaches the maximum and exhibits a uniform distribution of the pressure pulsation intensity. The spectral decomposition of the pulsating pressure reveals the existence of two dominating frequencies, which corresponds to the upstream pump turbine interaction and the downstream pump blade passing. Higher pump speeds enhance the pump turbine interaction and results in a more regular pressure pulsation, improving the hydrodynamic performance of the torque converter.

Modal analysis of the torque converter in different prestress

In order to study the mechanical properties and the dynamic performance of torque converter, to reduce the vibration and noise during the operation and to improve the stability, a 215mm hydraulic torque converter is taken as the research object, and modal analyses are performed based on the fi-nite element method. The weak parts of the impeller structure are obtained after calculating the mod-els of the impeller and turbine without prestress. The variation of the modal frequency of the turbine and impeller are obtained under different prestress conditions by calculating different rotational speeds of the transmission shaft. The fundamental frequencies of the impeller and the turbine in-crease by 0 . 43％ and 4 . 82％ respectively when the rotational speed ranges from 100 rpm to 4500 rpm. The results of the present research indicate that the modal frequencies at different speeds are similar to the fundamental frequencies of the structure. Therefore, it is possible to estimate the vibration characteristics of the structure and optimize the structural design by numerical modal analy-sis in the static state instead of the dynamic state.

Experimental approach for the analysis of the flow behaviour in the stator of a real centripetal turbine

During normal operation, radial turbines may work in off-design conditions. Off-design conditions may be characterised by very low expansion ratios, very high expansion ratios, very low rotational speeds or very high rotational speeds. All of these cases are difficult to characterise experimentally due to high experimental uncertainties or a lack of capabilities in the system feeding pressurised air to the turbine. Also, there are two- and three-dimensional computational fluid dynamics simulations at these operating points but could not be accurate enough due to high turbulence effects, flow detachment and shock wave generation. With a lack of high-quality data, experimental or computational, to fit the reduced-order turbine models used in zero- and one-dimensional engine simulations, there are large uncertainties associated to their results in off-design conditions. This work develops an experimental facility able to characterise the internal flow of radial turbine stators in terms of pressure and velocity fields at off-design and regular working conditions. The facility consists of an upscaled model of a radial turbine volute and stator fed with air in pressure- and temperature-controlled conditions, so different sensors can be used inside it with the least amount of flow disturbance. The different restrictions considered in the design of the upscaled model are presented, and their effects in the final experimental apparatus capabilities are discussed. A preliminary comparison between computational fluid dynamics simulations and experimental data shows encouraging results.

Improving energy performance of hydraulic torque converters

Torque converters are widely used in the transmissions of self-propelled vehicles for various purposes on wheeled and tracked chassis. A significant drawback of torque converters compared to mechanical transmissions is their relatively low efficiency. Therefore, the task of ensuring high efficiency values of torque converters in the entire range of gear ratios has been of importance since the invention of these hydraulic machines. Torque converters have the lowest efficiency values in the torque transformation mode among low and medium gear ratios from 0 to 0.7. In addition, the nature of the change in efficiency for an integrated torque converter in automatic transition to the fluid coupling mode also usually decreases sharply. This article discusses a number of motor and tractor torque converter designs aimed at obtaining high values of efficiency in the range of small or medium gear ratios. The considered technical solutions are associated with a reduction in energy losses when the working fluid enters the pump wheel of the torque converter.

Technological Analysis on Motor Stall and Its Perspective

The brush lock is due to assembly tightly during assembling three gripper so that it curls after some time in motor and bare motors. The motor happen to have current decreasing and cause rotary too slowly is an important technique problem. At last the motor hasn’t worked due to disconnection. It give company to bring assembly issue for customers. So the motor stall is main issue in motor working. We shall pay more attention to it necessarily and shall be strict quality inspection and we shall monitor the flow line for the sake of decreasing it. We shall solve the problem as soon as possible and communicate with the customer engineers. Unloaded rotation is radical in the base inspection. The engineer need to negotiate with supplying engineers for the qualified material of brush. Increasing inspection into more times is a method to decrease unqualified brushes. Some experiment method is explained to analyze for customer engineers. Two kinds of motors ie. stepping and asynchronous motor and motors used in future in car is explained to further knowledge to motor’s application. Such as the experiment with torque, voice and electric voltage converter. The pseudo soldering results the slow rotary. The reverse voltage is a reason for a motor to slow rotary even stall.

Combined Torque Converter for Mining Machines

Transmissions of many technological and transport machines for mining enterprises are equipped with hydro-mechanical transmissions (HMT) with torque converters. HMTs have a number of positive properties. But a significant drawback of traditional automotive single-stage (single-turbine) torque converters is their relatively narrow torque ratio, which most often makes 2 or 3. Multi-stage torque converters in which two or three turbines are simultaneously connected to the output shaft demonstrate higher converting properties. The toque ratio of multi-stage hydraulic torque converters makes 4-6 or more. The drop in the efficiency in the range of large ratios and the lack of hydraulic coupling mode is one of the disadvantages of multistage torque converters. In order to overcome these shortcomings, the design of a combined torque converter is proposed. It combines modes of operation with one and two active turbines, as well as modes of hydraulic coupling and blocking. The main turbine of a combined torque converter is of the centrifugal type. The combination of single-stage and two-stage operation modes is achieved through the use of a composite pump wheel, one part of which can be used as a second centrifugal turbine. Two clutches are provided to control the torque converter.