자기 강화 메커니즘을 이용한 클러치 토크 추정

김진욱(Jin-Wook Kim),최세범(SeiBum Choi) 한국자동차공학회 2020 한국자동차공학회 부문종합 학술대회 Vol.2020 No.7

In modern transmission control, fast and smooth shifting is the most important issue. Efficient power transfer requires fast shifting, and accurate slip control is necessary to improve the drivers ride comfort. In order to improve the slip control performance, it is very important to know the clutch torque. A clutch torque can be known from the clutch disk pressure and torque friction coefficient. The pressure applied to the clutch disk can be measured from the motor current and the force sensor. However, the torque friction coefficient cannot be measured by the sensor. Also, the friction coefficient is unknown because it changes with temperature, slip speed, and pressure on the clutch disk. Therefore, clutch torque estimation with the indirect method has been actively studied. In the forward-direction clutch torque estimation through the engine torque, the exact clutch torque cannot be estimated because the engine torque is inaccurate. Also, the backward-direction clutch torque estimation method using the compliance model has a disadvantage in that the clutch torque cannot be estimated when there is a backlash of the gear. Thus, in this manuscript, we propose a clutch disk torque friction coefficient estimation with a ball-ramp self-energizing mechanism. In the self-energizing mechanism in which the torque caused by friction reinforces the normal force, the gain of the actuator force to the clutch normal force varies according to the friction coefficient. Apply the actuators position and force to the model to obtain the change in gain and estimate the clutch disc torque friction coefficient. he ball-ramp actuator is modeled for the torque friction coefficient estimation, and the test bench experiment verifies the clutch torque estimation performance during shifting. Finally, verification of the proposed model and estimation of the clutch disc torque friction coefficient during shifting are conducted via test bench experiments.

마찰에 의한 토크 꼬임 발생 기구의 이론적 고찰

임정호,간바트,허유,Lim, Jung Ho,T., Ganbat,Huh, You 한국섬유공학회 2014 한국섬유공학회지 Vol.51 No.5

This research comprises a theoretical investigation of the bundle twists created by the bundle thickness distribution while a bundle rotates by frictional force. The torque from the thickness differentials generates the twists of interest (i.e., the resulting rotation bundle differentials found in the friction area). Therefore, a theoretical model describing the dynamics of the twists per length was derived by applying continuous torque. The temporal bundle thickness is also considered. Using the model, the temporal profiles and spatial distributions of the torque twists are characterized. Under an arbitrarily chosen condition that allows simple interpretation of the torque twist characteristics, the governing equation system consisting of the model for the temporal distributions of the bundle radius on the friction drum surface and the model for the dynamic torque twists is solved, and the generation mechanisms of the torque twists are characterized. Results show that the torque twists propagate along the bundle axis in the form of a moving wave during the short time when the bundle first passes through the friction zone. After the bundle reaches a steady state, the torque twists increase very fast and then slow down as the bundle is moved by the take-up operation. Thus, the central area around the bundle axis becomes highly twisted by the superposition of the torque twists. This is because the input fleece fibers at the center accumulate for a longer distance than for the area near the bundle surface. However, at the exit of the friction area, the number of torque twists is almost zero because there is no accumulation distance for the torque twists to occur. This indicates that the torque twists are distributed with respect to the radial direction. This arc of torque-twist distribution can be described by a reciprocal relationship with respect to the radial position of the bundle cross-section.

회전 마찰형 제진장치의 이력특성에 대한 실험적 연구

박진영,한상환,문기훈,이강석,김형준 한국지진공학회 2013 한국지진공학회논문집 Vol.17 No.5

Friction energy dissipative devices have been increasingly implemented as structural seismic damage protecting systems due to their excellent seismic energy dissipating capacity and high stiffness. This study develops rotational friction energy dissipative devices and verifies experimentally their cyclic response. Based on the understanding of the differences between the traditional linear-motion friction behavior and the rotational friction behavior, the configuration of the frictional surface was determined by investigating the characteristics of the micro-friction behavior. The friction surface suggested in this paper consists of brake-lining pads and stainless steel sheets and is normally stressed by high-strength bolts. Based upon these frictional characteristics of the selected interface, the rotational friction energy dissipative devices were developed. Bolt torque-bearing force tests, rotational friction tests of the suggested friction interfaces were carried out to identify their frictional behavior. Test results show that the bearing force is almost linearly proportional to the applied bolt torque and presents stable cyclic response regardless of the experimental parameters selected this testing program. Finally, cyclic tests of the rotational friction energy dissipative devices were performed to find out their structural characteristics and to confirm their stable cyclic response. The developed friction energy dissipative devices present very stable cyclic response and meet the requirements for displacement-dependent energy dissipative devices prescribed in ASCE/SEI 7-10.

토크 및 모멘트부하의 영향을 고려한 로봇 관절의 마찰 모델

김태정(Tae Jung Kim),안국현(Kuk-Hyun Ahn),송재복(Jae-Bok Song) 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.1

로봇 관절에서 발생하는 마찰은 제어시스템에 외란으로 작용하여 제어성능을 악화시키는 요인으로 작용한다. 따라서 대부분의 로봇에서는 마찰 모델을 기반으로 추정한 마찰토크를 제어입력에 반영하여 마찰을 보상하며, 마찰 모델이 정확할수록 로봇의 제어성능을 향상시킬 수 있다. 본 연구에서는 로봇링크의 하중에 의해서 발생하는 토크부하와 모멘트부하의 영향으로 다르게 발생하는 마찰 거동을 파악한다. 이를 통해 기존의 쿨롱마찰과 점성마찰로 구성된 마찰 모델에 토크부하와 모멘트부하의 영향을 고려한 항을 추가하여 보다 정확한 마찰 모델을 제안한다. 제안한 마찰 모델은 7자유도 협동로봇에 적용하여 실험을 통해 성능을 검증하였다. The friction generated in a robot joint acts as a disturbance in a control system, which affects the control performance. Therefore, in most robots, friction is compensated for by adding the estimated friction value in the control input based on the friction model. Thus, the more accurate the friction model, the better the control performance of the robot. In this study, the friction that occurred differently owing to the torque and moment loads caused by the robot links were analyzed. Through the analysis, a friction model that included the effects of torque and moment loads from the robot links was developed to improve the conventional friction model based on only the Coulomb friction and viscous friction. The proposed friction model was verified experimentally by applying the model to a 7DOF collaborative robot.

Engine Oil Jet System이 Engine Friction에 미치는 영향에 대한 연구

민선기(Sun-Ki Min) 한국산학기술학회 2016 한국산학기술학회논문지 Vol.17 No.6

엔진에 터보차져를 사용하게 되면 엔진의 출력도 향상되지만 동시에 엔진의 온도도 높아지게 된다. 특히 피스톤의 경우는 냉각이 문제가 된다. 이러한 문제를 해결하기 위하여 오일 젯을 사용하는데, 오일 젯은 오일을 피스톤의 밑 부분에 분사하여 피스톤을 냉각시키는 것이다. 오일 젯이 사용된다면, 오일의 분사로 인하여 오일 유량의 증가및 피스톤으로부터의 열전달에 의하여 높아진 오일 온도 문제를 해결하기 위하여 오일 펌프 용량 증대와 오일 쿨러의 사용이 필요하다. 그러나 용량 증대 오일 펌프와 오일 쿨러를 사용하면 엔진의 마찰 토크가 증가하는 원인이 된다. 본 연구에서는 오일 젯, 오일 쿨러 및 오일 펌프의 용량 증대로 인하여 엔진의 마찰 토크가 증가하는 정도에 대하여 연구하였다. 또한 각 부품의 사양을 변경함 에 따라 마찰 토크가 얼마나 영향을 받는가도 측정되었다. 저속에서는 오일 펌프와 오일 쿨러에 의한 영향이 크고 고속에서 는 오일 쿨러에 의한 영향이 큼을 알 수 있었다. When turbochargers are applied to engines, the temperature of the engine becomes high, making the cooling of pistons very important. To solve this problem, an oil jet is used. The oil jet provides oil to the underside of piston for cooling. When an oil jet is used, oil pump size-up and oil cooler are needed because of the increased oil flow rate and higher oil temperature. On the other hand, these increase the friction torque of the engine. This study examined how much the friction torque of an engine increases by an oil jet, oil cooler, and oil pump size-up. In addition, the proportions of the friction torque of the engine increased by each part were measured by changing the engine assembly condition. At low speed, the oil pump and oil cooler had a larger effect on the friction torque than the other factors. At high speed, oil cooler had a larger effect than the other factors.

Modeling of Friction Torque Based on Turntable Servo System Using Neural Network with Memory Storage Unit

Cheng Xie,Songlin Chen,Yang Liu 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.7

Friction is the main factor affecting the performance of the servo systems. The tracking accuracy can be effectively improved by compensating the rotational torque online with the accurate value of friction torque. Therefore, it is necessary to build a friction model, which can accurately describe the friction characteristics of the servo systems during operation. This paper proposes a neural network model based on the mechanical characteristics of friction. The memory storage unit is added to the network structure to store the state information between the current and the next speed reversal time so as to process the dynamic and static friction characteristics separately. To eliminate the quantization noise existing in the angular velocity calculated by the angular position difference, the Savitzky-Golay convolution smoothing algorithm is used to smooth the angular velocity and the genetic algorithm is used to determine the sliding window size and the fitting polynomial order. The simulation results show that the neural network model proposed in this paper can reproduce the characteristics of the dynamic and static friction torque well, and the fitting effect is better than that of the feedforward network and LuGre model under different forms of excitation signals, so it has strong generalization ability and predictive accuracy. In addition, the modeling process can be effectively simplified, thus verifying the effectiveness and superiority of the proposed method.

DC-link 전압변동을 고려한 PMSM 토크제어의 성능 향상 방법

이정효(Jung-Hyo Lee),원충연(Chung-Yuen Won) 한국조명·전기설비학회 2014 조명·전기설비학회논문지 Vol.28 No.11

This paper proposes a PMSM torque control method considering DC-link voltage variation and friction torque. In general EV/HEV application, two dimensions look-up table(2D-LUT) is used for reference current generation due to its stable and robust torque control performance. Conventionally, this 2D-LUT is established by flux-torque table to overcome the DC-link voltage variation. However, the flux table establishment is more complex than the speed table establishment. Moreover, one flux data reflects several speed conditions in variable DC-link voltage, friction torque cannot be considered by using the flux table. In this paper, speed-torque 2D-LUT is used for current reference generation. With this table, PMSM torque control is well achieved regardless of DC-link voltage variation by the proposed control method. Simulation and experimental results validate improvement of torque control error through friction torque compensation.

A Numerical Approach to Determine the Frictional Torque and Temperature of an Angular Contact Ball Bearing in a Spindle System

김강석,이득우,이상민,이승준,황주호 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

The purpose of a ball bearing is to reduce the rotational friction and support radial and axial loading. But it can't avoid the heatgeneration by the friction, the wear and the power loss it was caused by the relative motion between the metal materials. Heat isgenerated by the friction in the bearings, which causes the temperature inside the bearing to increase. If the heat is not appropriatelyremoved from the bearing, elevated temperatures may give rise to premature failure. It is, therefore, important to be able to calculatethe temperature in the bearings due to friction. Here, we describe a method to estimate the equilibrium temperature on the angularcontact ball bearing in a spindle system using a numerical approach. The frictional torque of the bearing in a spindle system wascalculated by use of a bearing analysis tool and thermal analysis of the spindle system including the bearings was achieved usingthe finite element method (FEM). The actual spindle system with the same layout of the FEA was built and the frictional torque, thebearing temperature were measured in the experiment. The bearing temperature was compared with measured data to verify thevalidity of finite element analysis.

습식 DCT의 드래그 토크 저감을 위한 클러치 패드 유로 설계

조정희(Junghee Cho),한준열(Juneyeol Han),김우정(Woo-Jung Kim),장시열(Siyoul Jang) 한국트라이볼로지학회 2017 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.33 No.2

The drag torque in the wet clutch system of a dual clutch transmission system is investigated because it is relatively high, up to 10 of the total output torque of the engine, even when the clutch is in the disengagement state with zero torque transfer. Drag torque results from the shear resistance of the DCTF between the friction pad and separator plate. To reduce the drag torque for ensuring fuel economy, the groove pattern of the wet clutch friction pad is designed to have a high flow rate through the pattern groove. In this study, four types of groove patterns on the friction pad are designed. The volume fraction of the DCTF (VOF) and hydrodynamic pressure developments in the gap between the friction pad and separator plate are computed to correlate with the computation of the drag torque. From the computational results, it is found that a high VOF and hydrodynamics increase the drag torque resulting from the shear resistance of the DCTF. Therefore, a patterned groove design should be used for increasing the flow rate to have more air parts in the gap to reduce the drag torque. In this study, ANSYS FLUENT is used to solve the flow analysis.

Improved Formulation for Running Torque in Angular Contact Ball Bearings

Van-Canh Tong,홍성욱 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.1

This paper presents an improved computational model for the angular contact ball bearing (ACBB) running torque. Considering the general loading condition, the friction torque formula of individual bearing balls was derived. Five friction components were considered: elastohydrodynamic lubrication (EHL) rolling resistance, elastic hysteresis friction, differential sliding loss, spinning friction, and lubricant viscous drag effect. The formulas for elastohydrodynamic lubrication rolling resistance and spinning friction, which contribute significantly to the ACBB running torque, were improved by investigating and re-formulating the contact related formulas. The friction coefficient between the ball and races was investigated in order to choose a suitable and reliable formula for the proposed model. The proposed model was verified through a comparison with formulas provided by a bearing manufacturer and with a set of experimental data.