Lock-up Clutch Research Articles

Research on energy‐saving technology of loader hydraulic torque converter based on MATLAB dynamic characteristic simulation

AbstractAt present, hydraulic transmission loaders have high automatic adaptability and convenient operation, but their transmission efficiency is low, and the intelligent degree of energy consumption regulation is limited. Strengthening the research of locking device in torque converter is an important measure to effectively reduce energy consumption. Therefore, the research uses MATLAB software and torque converter parameters to build the external characteristic curves of the engine and torque converter, and builds the dynamic model based on the working principle and locking process of the lockup clutch. The research and experimental analysis are carried out from three aspects of the lockup dynamic process of the torque converter, the lock‐up and unlocking conditions, and the change of the lockup oil pressure of the clutch. The results show that the speed difference range between pump wheel and turbine (233.08–365.44 rpm) is much lower than that of other cases (409.68–616.23 rpm) when the engine and torque converter are matched. And the fuel rate is the highest when the throttle opening of the loader is 70%, about 38%. The above results show that the locking structure of the hydraulic torque converter of the loader can effectively reduce the working vibration and improve the service life and fuel rate. And its energy‐saving application effect has an important enlightening effect on the performance optimization and resource utilization of construction machinery, and provides new ideas for improvement.

Fundamental study of centrifugal pendulum vibration absorber with physical pendulum to suppress the torsional vibration in automatic transmission for cars

In the latest trend in engine technology, high-power engines and low cylinder engines are widely used. These engines contribute to strong torsional vibration due to engine combustion within the powertrain systems. On the other hand, automatic transmission (AT) is required to use a lock-up clutch system which links engine and gear train directly from low engine rotation speed. Lock-up damper, torsional spring in torque converter, is not enough to absorb the torsional vibration. Therefore, the centrifugal pendulum vibration absorber (CPVA) is developed to suppress the torsional vibration. The natural frequency of CPVA is proportional to engine rotation speed. Then it is expected to suppress torsional vibration in wide range of the engine rotation speed. However, the natural frequency of the CPVA varies due to the nonlinear when the vibration amplitude of CPVA is large. There is a space limitation problem to install larger size of CPVA to suppress the strong torsional vibration. To overcome this problem, a new physical pendulum type of centrifugal pendulum vibration absorber is developed. In this study, the optimal design for the physical pendulum type of centrifugal pendulum vibration absorber is discussed.

Coordinated Torque, Energy and Clutch Control Strategy for Downshifts in P2 Parallel xHEV Powertrains

<div class="section abstract"><div class="htmlview paragraph">This paper describes a methodology for investigating the controls coordination of clutch and propulsion torque sources relative to clutch energy, electrification energy consumption and output torque profile for offgoing controlled downshifts in P2 parallel xHEV powertrain configurations. The focus is on an 8 speed planetary automatic transmission, but the approach is equally applicable to any powerflow design with clutch-to-clutch shifting. The modeling technique is for an overall control strategy relative to achieving a targeted transmission input speed profile. A reduced order model of the transmission system is presented that accounts for input shaft acceleration and compensation of inertial contributions to offgoing clutch torque and transmission output torque. The coordinated control of offgoing clutch, engine and P2 electric motor torques are explored in the context of power on and off downshifts for clutch energy, P2 energy consumption and output torque trajectory that directly translates to responsiveness and/or perceived shift quality. The presence of a torque converter and lockup clutch and the influence of the lockup clutch state control on downshifting coordination and torque disturbance is also incorporated in the analysis. Potential improvements in downshift response, clutch controllability and output torque trajectory are provided for the particular 8 speed transmission powerflow considered. The methodology presented can easily be applied to any clutch-to-clutch transmission architecture and powerflow, whether planetary, dual clutch or other.</div></div>

Development of Artificial Intelligence to Classify Quality of Transmission Shift Control Using Deep Convolutional Neural Networks

Automatic transmissions are a core component of modern vehicles, and achieving good shift quality is critical to enhance the driving experience. In companies that manufacture transmissions, expert engineers take great care in calibrating parameters for controlling hydraulic pressure with the goal of achieving targeted shift quality. Because we need human experts to evaluate shift quality, it is hard to shorten the time taken to calibrate the systems controlling hydraulic pressure. In this paper, to reduce such development time, we propose a novel framework of a Classifier of Shift Quality; it applies the standard Supervised Deep Learning techniques (CSQ-SDL) to time-series measurement data. The framework consists of five procedures: measurement data collection, labeling by experts, data augmentation, data standardization, and the training of deep convolutional neural networks. Moreover, we also carry out driving experiments in which CSQ-SDL is used to assess the engagement of the lock-up clutch of a specific transmission model. By using raw time-series data measured by ordinary sensors in advance, and labels written later by an expert engineer looking at the raw data, we build binary classifiers and test their performance. It turns out that the accuracy of predicting expert's judgment is high; the area under the curve is 0.94. The result indicates that the proposed method is capable shortening product development times and thus meeting the demands of today's competitive automotive market.

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.

Research on Longitudinal Collapse Mode and Control of the Continuous Bridge under Strong Seismic Excitations

Bridge collapse events are common in major earthquakes around the world, among which continuous girder bridges are the most involved. In order to explore the collapse mechanism of a continuous girder bridge in an earthquake, the collapse mode of a two-span continuous girder bridge specimen which had been studied by the shaking table test was analyzed. Then, on the basis of the conventional plate rubber bearing system, the collapse control strategies which were high damping rubber bearing, fluid viscous damper, lock-up clutch control methods were discussed. It is found that high damping rubber bearing can delay the collapse time but the collapse mode remains the same; lock-up clutch has the best displacement control effect for the superstructure, but its energy consumption performance is not as good as that of a fluid viscous damper; high damping rubber bearing is quite suitable for protecting the substructure under short-period ground motion to avoid the bridge collapse caused by the failure of piers; fluid viscous damper and lock-up clutch are suitable for protecting the superstructure under long ground seismic motion to avoid the bridge non-use resulted from girder lowering; three collapse control methods can improve the anti-collapse ability of the bridge specimen, although no matter which control method is used, the bridge specimen may still collapse under strong earthquakes, but the target of postponing collapse time can be realized by means of various effective control methods.

Basics Of Generation Of Recent Gadget For Speed Alteration Administration

The article deals with drawback of speed alteration administration in engineering, i.e., hoisting, building, road and land reclamation machines, cars and tractors, machine tools and different instrumentality. The review of the ways and gadget for stepped, steppless and combined speed alteration method administration are performed. Their major disadvantages are known. Among others, main disadvantages of stepped speed administration gadget square measure the quality of style, their giant material consumption, the emergence of dynamic masses throughout the transition from one speed to a different, even just in case of system exploitation. endlessly variable speed gadget have intense elements wear because of the utilization of friction connections like brakes or lock-up clutches. The authors result in the conclusion regarding the requirement for brand new gadget of speed alteration administration to get rid of, or a minimum of decrease, known deficiencies. New gadget recommended for speed changes administration via gear wheel trains with a loop hydrosystem. Those new constructions square measure alleged to take away abovementioned shortcomings and might be the idea and foundation for brand new gadget generation and their any analysis.

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.

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.

Control and Simulation of Torque Converter Lock-up Clutch

Considering the requirements of dynamic performance and quality during the torque converter locking process, a two parameters latch-up control strategy was designed, and a simulation method to study the control performance by use of processor in loop (PIL) simulation technology was proposed. Through the study of the practically applied requirements of a loader, a two parameter lock-up control strategy with turbine speed signal and gear signal as main control parameters was developed. According to the control strategy, the logic diagram of real-time locking and unlocking control of the latch-up clutch was established by using Matlab/Simulink. Then, PIL technology was used to realize the co-simulation of CCS and Simulink. Simulation results show that the latch-up control model is correct and the lock-up clutch can effectively lock and unlock in accordance with the lock-uprule.

Fundamental study on countermeasures against subharmonic vibration of order 1/2 in automatic transmissions for cars

In automatic transmissions for cars, a damper is installed in the lock-up clutch to absorb torsional vibrations caused by combustion in the engine. Although a damper with low stiffness reduces the torsional vibration, low-stiffness springs are difficult to use because of space limitations. To address this problem, dampers have been designed using a piecewise-linear spring having three different stages of stiffness. However, a nonlinear subharmonic vibration of order 1/2 occurs because of the nonlinearity of the piecewise-linear spring in the damper. In this study, we experimentally and analytically examined a countermeasure against the subharmonic vibration by increasing the stages of the piecewise-linear spring using the one-degree-of-freedom system model. We found that the gap between the switching points of the piecewise-linear spring was the key to vibration reduction. The experimental results agreed with results of the numerical analyses.

自動車用トルクコンバータのロックアップクラッチの動特性解析

The torque converter is a kind of fluid coupling that is widely used as a start-up device for automobiles equipped with an automatic transmission. A lock-up clutch is often incorporated in the torque converter in order to improve vehicle fuel economy in the higher speed ratio range. This improvement is obtained because the lock-up clutch can reduce fluid losses by engaging the input and output shafts to rotate at relative speeds with only a small amount of slip. Operation of the lock-up clutch is controlled mainly by supply and discharge oil pressure of the torque converter. The purpose of this study was to better understand clutch behavior under the influence of oil flow. Flow through the lock-up clutch was computed by using a commercial CFD code at three speed ratios of 0.8, 1.0 and 1.2 under the prescribed supply and discharge oil pressure sequence. Unsteady computations were conducted under the assumption that the flow was weakly coupled with the solid mass motion. Quasi-steady computations were also conducted under the assumption that a dynamically equilibrium state was maintained when the clutch moved. The results showed that the response time of the lock-up clutch increased with a higher speed ratio and that flow through the clutch changed directions from outward to inward in the engagement process in all cases. The computed response time coincided reasonably well with the experimental data obtained with the actual machine. It was also found that the quasi-steady analysis results showed an unreasonable or meaningless tendency regarding the response time.

Optimal Design of Spring Characteristics of Damper for Subharmonic Vibration in Automatic Transmission Powertrain

In the torque converter, the damper of the lock-up clutch is used to effectively absorb the torsional vibration. The damper is designed using a piecewise-linear spring with three stiffness stages. However, a nonlinear vibration, referred to as a subharmonic vibration of order 1/2, occurred around the switching point in the piecewise-linear restoring torque characteristics because of the nonlinearity. In the present study, we analyze vibration reduction for subharmonic vibration. The model used herein includes the torque converter, the gear train, and the differential gear. The damper is modeled by a nonlinear rotational spring of the piecewise-linear spring. We focus on the optimum design of the spring characteristics of the damper in order to suppress the subharmonic vibration. A piecewise-linear spring with five stiffness stages is proposed, and the effect of the distance between switching points on the subharmonic vibration is investigated. The results of our analysis indicate that the subharmonic vibration can be suppressed by designing a damper with five stiffness stages to have a small spring constant ratio between the neighboring springs. The distances between switching points must be designed to be large enough that the amplitude of the main frequency component of the systems does not reach the neighboring switching point.

Fundamental study of subharmonic vibration of order 1/2 in automatic transmissions for cars

A torque converter is an element that transfers torque from the engine to the gear train in the automatic transmission of an automobile. The damper spring of the lock-up clutch in the torque converter is used to effectively absorb the torsional vibration caused by engine combustion. A damper with low stiffness reduces fluctuations in rotational speed but is difficult to use because of space limitations. In order to address this problem, the damper is designed using a piecewise-linear spring with three stiffness stages. However, the damper causes a nonlinear vibration referred to as a subharmonic vibration of order 1/2. In the subharmonic vibration, the frequency is half that of the vibrations from the engine. In order to clarify the mechanism of the subharmonic vibration, in the present study, experiments are conducted using the fundamental experimental apparatus of a single-degree-of-freedom system with two stiffness stages. In the experiments, countermeasures to reduce the subharmonic vibration by varying the conditions of the experiments are also performed. The results of the experiments are evaluated through numerical analysis using the shooting method. The experimental and analytical results were found to be in close agreement.

Application of dual-blade stator to low-speed ratio performance improvement of torque converters

With application of the lock-up clutch in the torque converter (TC), fuel economy is not much determined by its high-speed ratio transmission efficiency. As a benefit, more researches are focused on its low-speed ratio performance so as to improve vehicle gradeability and launching acceleration performance. According to the results of computational fluid dynamics (CFD) analysis, hydrodynamic loss inside the stator cascade accounts for 42% of the total energy loss at stalling speed ratio. It is found that upstream flow with large impingement angle results in boundary layer separation at the leading edge, which aggregates hydrodynamic loss and decreases circular flow rate dramatically at low-speed ratio. In this paper, a dual-blade stator is proposed to suppress the boundary layer separation, which is parameterized by using the non-uniform rational B spline (NURBS) method. The mean camber line and blade profile curve are expressed by a three control points quadratic open NURBS and a cubic closed one respectively. The key design parameters included the slot width and suction side shape of the primary blade are analyzed. The most effective slot width is found to be between 4% and 8% chord length, and the boundary layer separation can be suppressed completely by decreasing distribution of momentum moment at the primary blade and adding it to the leading edge of the secondary blade. As a result, circular flow rate and impeller torque capacity is increased by 17.9% and 9.6% respectively at stalling speed ratio, meanwhile, low-speed ratio efficiency is also improved. Maximum efficiency at high-speed ratio decreases by 0.5%, which can be ignored as the work of lock-up clutch. This research focuses on using the dual-blade stator to optimize low-speed ratio performance of the TC, which is benefit to vehicle power performance.

自動車用ATにおける分数調波振動に関する基礎実験および理論解析

A torque converter is an element to transfer torque from the engine to the gear train in an automatic transmission vehicle. There is a damper spring on the lock-up clutch in the torque converter that reduces the amplitude of vibration caused by engine combustion. The damper is designed using a piecewise-linear spring with three stages in order to address a problem of space limitations. However, the damper causes a nonlinear vibration called subharmonic vibration of order 1/2. The frequency of the subharmonic vibration is half of the engine forced vibration frequency. In this study, in order to clarify the occurrence mechanism of the subharmonic vibration caused by the non-linearity of a piecewise-linear spring, fundamental experiments and numerical analysis were performed. The experimental setup is single-degree-of-freedom system that has two stiffness stages and the numerical analysis was performed under same condition as the experiment by using shooting method. According to the results of the experiments and numerical analysis, it was found that the subharmonic vibration occurs when the excitation frequency is near the twice of the resonance frequency and the equilibrium point is around a switching point of spring stiffness, and the smaller stiffness ratio and larger damping can suppress the subharmonic vibration. Also, the experimental and analytical results were well agreed with each other and the correctness of the experimental results were confirmed.

自動車用ATのロックアップクラッチすべり制御時における振動現象の数値解析

自動車用ATのロックアップクラッチすべり制御時における振動現象の数値解析

Frictional Behavior of a Wet Clutch Using Blends of Automatic Transmission Fluid (ATF) and Biolubricant (Jatropha Oil) in a Pin-on-Disk Tester

Nowadays, biolubricants are being used to replace mineral lubricants totally or partially and it is of great importance due to interest in environmental protection. Jatropha oil is a good alternative as lubricant feedstock and combustible. Its production is cheap in comparison to other vegetable oils. In México, Jatropha curcas L. is widely distributed in more than 15 states, which makes a sustainable supply of this natural resource possible. The aim of this work was to investigate the frictional behavior of blends of automatic transmission fluid with vegetable oil tested in a pin-on-disk rig simulating the wet clutch operation. Two different friction materials were separately tested and used as pins against actual steel disks from a wet clutch. The frictional behavior results demonstrated that the mixtures presented antishudder characteristics. Thus, Jatropha oil could be potentially used as part of automatic transmission fluid (ATF) formulations to enhance their antishudder properties and increase the efficiency of the torque transferred of wet clutches with a controlled lock-up clutch system, which improves the full economy of vehicles.

Optimal Servo Design for Lock-Up Slip Control for Torque Converter—Nonlinear Output Regulation Approach

It is well known that slip control of lock-up clutch in automatic transmission systems is a crucial technology for improving fuel economy and driving comfort. However, plant parameters rapidly vary according to turbine speed, making the slip control challenging. For this problem, we apply nonlinear output regulation theory for the system represented as a linear parameter-varying system with the turbine speed as the parameter. In this framework, it is possible to design a servo controller that is optimally scheduled according to the turbine speed. The effectiveness of the proposed method is confirmed by experiments compared with an $H_{\infty }$ controller, which is one of the most advanced methods employed in the field of lock-up clutch slip control.

Research on the torque transmissibility of the passive torsional vibration isolator in an automotive clutch damper

The input torque vibrations (i.e. the fluctuations or ripples) induced by internal-combustion engines is a significant source of noise, vibration and harshness issues, which cause problems in automotive powertrains. This is because the torque vibrations are primarily transmitted to the input shaft of automotive transmissions (e.g. automatic transmissions) when the lock-up clutch is closed. Hence, a passive torsional vibration isolator with helical springs is generally inserted between the engine and the transmission to isolate the input vibratory energy. Although a passive isolator is used to resolve the noise, vibration and harshness issues because it generally exhibits frequencies with a very low transmissibility, the primary performance of the isolator is evaluated using only the static torsional spring characteristics and the measurement of the angular velocity or the angular acceleration. In this study, a low-inertia dynamometer incorporating state-of-the-art torque-sensing technology was used to evaluate experimentally the torque transmissibility of a torsional vibration isolator as a primary dynamic performance index for the first time.