• Title/Summary/Keyword: Rack friction

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Rack Force Estimation Method using a Tire Mesh Model (TIRE MESH 모델을 활용한 랙추력 추정법 개발)

  • Kim, Minjun;Chang, Sehyun;Lee, Byungrim;Park, Youngdae;Cho, Hyunseok
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.3
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    • pp.130-135
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    • 2014
  • In this paper, a new estimation method is proposed to calculate steering rack axial force using a 3 dimensional tire mesh model when a car is standing on the road. This model is established by considering changes of camber angle and contact patch between the tires and the ground according to steering angle. The steering rack bar axial force is estimated based on the static equilibrium equations of forces and moments. A tire friction force is supposed to act on the center point of the contact patch, and the proportional coefficient of friction depending on contact patch is suggested. Using the proposed estimation method, rack axial force sensitivity analysis is evaluated according to changes of suspension geometry. Then optimal motor power of Motor Driven Power Steering(MDPS) is evaluated using suggested rack forces.

Seismic Response Analysis of a Two-Mass Rack System Considering Frictional Behavior (마찰거동을 고려한 이중질량시스템의 지진응답해석)

  • Park, Kwan-Soon;Ok, Seung-Yong;Lee, Jeeho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.31 no.6
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    • pp.347-352
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    • 2018
  • This study proposes seismic response analysis technique of a two-mass rack system which sustains heavy loads with frictional behavioral characteristics. In order to deal with the nonlinear frictional characteristics of the mass on the rack system, the equations of motion of the system has been derived and the appropriate numerical simulation technique has been developed. In order to examine the seismic performance of the proposed system, we consider two parameters that are expected to have great influence on the seismic performance of the system. One is the ratio of the two masses of the load and the rack structure, and the other is the friction coefficient between rack and loaded mass. A number of numerical simulations of the seismic response of structures with various natural frequencies for both parameters have been performed in order to investigate the seismic safety of the rack structures. From the simulated results. it is observed that the maximum displacement of the rack system tends to decrease drastically as the natural frequency of the structure increases regardless of the two parameters of mass ratio and friction coefficient. The proposed study provides important reference data to guarantee the seismic safety of the rack system by considering nonlinear frictional behavior of the loaded mass.

Case Study of Tribological Failure Characteristics in Automotive Steering System (자동차 조향장치의 트라이볼로지적 고장특성에 관한 사례연구)

  • Kim, Chung-Kyun;Lee, Il-Kwon;Cho, Seung-Hyun
    • Tribology and Lubricants
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    • v.26 no.1
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    • pp.61-67
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    • 2010
  • The purpose of this paper is to study and analyze the failure examples on tribological characteristics of an automotive steering system. In this failure study, the grease leakage may stick leaked grease, dust, and wear particles between pinion and rack gears in mechanical steering system. In the case of seal failures such as a rod seal, o-ring and oil seals, the gear box and oil pump do not operate properly due to lack of oils. This means that oil pump does not supply a working fluid and produce a normal oil pressure of the steering system. This leads to leak a working fluid from the seals and produce a wear between pinion and rack gears. Especially, the leaked oil is usually mixed with internal wear particles and foreign dust/fine sands. Thus no leakage of working oils is very important design concepts, which is strongly related to the sealing components and smoothly operating of the mechanical friction parts of power steering system.

Effects of Design Parameters on the Ergonomic Quality of a Self-Closing Drawer (자동귀환 서랍의 감성품질에 대한 설계인자 영향 분석)

  • Seo, Man Cheol;Kim, Kwon Hee
    • Journal of the Korean Society for Precision Engineering
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    • v.33 no.8
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    • pp.655-660
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    • 2016
  • Self-closing drawers are used in high-end products, such as furniture, home appliances, and a range of other storage devices. In this study, a self-closing mechanism is proposed. A system consisting of a friction latch, constant force spring, rotary damper with rack, and pinion is developed. The retracting drawer can be latched at any position and can be reactivated by simple touch. The constant force spring and rotary damper offer smooth closing action. The ergonomic quality of the closing action is quantified by an index based on velocity-time behavior. The effects of various design parameters are analyzed with a dynamics model and experimentally validated by prototype testing.

Sensitivity Analysis of Steering Wheel Return-ability at Low Speed

  • Cho, HyeonSeok;Lee, ByungRim;Chang, SeHyun;Park, YoungDae;Kim, MinJun;Hwang, SangWoo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.25 no.2
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    • pp.167-178
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    • 2017
  • The steering wheel of a vehicle has a typical characteristic of automatically returning to its neutral state when the driver releases it. Steering returnability originated from the tire forces and kingpin moments. It is proportional to the reaction torque that is generated through the rack and column, which are dependent on suspension and steering geometry. It is also important to accurately predict and design it because steering returnability is related to steering performance. In this study, a detailed multibody dynamics model of a vehicle was designed by using ADAMS/Car and simulated for steering returnability. In addition, a tolerance analysis of the chassis system in terms of part dimension and properties has been performed in order to minimize the design parameters. The sensitivity of the selected design parameters was then analyzed via Design of Experiments(DOE). As a result, we were able to obtain the main parameters through a contribution analysis. It can be used to predict steering returnability and improve its performance, which is represented by the angle of restoration and laterality.

Development of Anti-Rolling Demo System for Mobile Harbor Using Maglev Type AMD (자기부상방식 AMD를 이용한 모바일 하버용 횡동요 저감 데모 장비의 개발)

  • Park, Cheol-Hoon;Ham, Sang-Yong;Kim, Byung-In;Lee, Sung-Whee;Park, Hee-Chang;Cho, Han-Wook;Moon, Seok-Jun;Chung, Tae-Young
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.1
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    • pp.40-47
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    • 2011
  • Mobile harbor which is a novel concept of ocean transportation to bring the containers from the cargo ship waiting on the ocean away is being focused now. To provide the mobile harbor with the stable loading/unloading condition, it is necessary to develop the oscillation mitigation technologies such as anti-rolling system. Anti-rolling system using AMD(Active Mass Driving) has merits that it can handle the disturbances more actively and mitigate the rolling oscillation faster than other type anti-rolling system. However, rack-and-pinion type AMD has problems such as big friction noise from gears and motor, wear and tear, and continuous maintenance. In this paper, novel anti-rolling system using Maglev type AMD for mobile harbor is suggested in order to resolve the problems caused by the friction. This novel anti-rolling system doesn't make any friction because it supports the moving mass by using magnetic levitation force and moves it by using propulsion force from the linear motor. The demo system of the novel anti-rolling system using maglev type AMD has been developed in order to investigate its feasibility. This paper presents the procedures and results of development of this demo system.

The Design of a Speed-position Controller using a Parameter Estimation Method for the Linear Brushless DC Motor (파라미터 추정방법을 이용한 선형추진브러시리스 직류전동기의 속도-위치제어기 설계)

  • 박성수;최중경;변지섭;윤성은;류정오
    • Proceedings of the IEEK Conference
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    • 2001.06e
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    • pp.143-146
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    • 2001
  • Servomotors, especially linear brushless servomotors have numerous advantages over ball screws, timing belts, rack/pinion drives and friction drives compared wi th rotary servomotors This paper proposes an linear regression method as the estimated ion of unknown parameters from the linear brushless DC motor The estimated parameters are used to tune the gain of controller. In order to agree with this purpose, Digital Signal Processor (TMS320F240), developed for implementation of the motor control, is adopted in this study. The processor playing an important role in controller has A/D converters, PWM generators, riched I/O ports internally.

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A Study on Improvement of the Thermal Stability for Development of Linear Motors with High Speed and Accuracy (고속.정밀 이송용 리니어모터 개발을 위한 열적 안정성 향상에 관한 연구)

  • Hwang, Young-Kug;Lee, Choon-Man;Eun, In-Ung
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.6
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    • pp.126-133
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    • 2008
  • Linear motors are efficient mechanism that offers high speed and positioning accuracy. By eliminating mechanical transmission mechanisms such as ball screw or rack-pinion, much higher speed and greater acceleration can be achieved without backlash or excessive friction. However, an important disadvantage of linear motor system is its high power loss and heating up of motor and neighboring machine components on operation. For the application of the linear motors to precision machine tools an effective cooling method and thermal optimizing measures are required. This paper presents an investigation into the thermal behavior of linear motors with the objective of deriving the optimum cooling conditions. To reach these goals several experiments were carried out, varying operating and cooling conditions. From the experimental results, this research proposed cooling conditions to improve the thermal characteristics of the linear motors.

A Study on the Cooling Parameter Decision of Linear Motor System by Finite Volume Method (유한체적법을 이용한 리니어모터 시스템의 냉각조건 선정에 관한 연구)

  • Hwang Y.K.;Eun I.E.;Lee C.M.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.449-450
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    • 2006
  • Development of a feed drive system with high speed, positioning accuracy and thrust has been an important issue in modern automation systems and machine tools. Linear motors can be used as an efficient system to achieve such technical demands. By eliminating mechanical transmission mechanisms such as ball screw or rack-pinion, much higher speeds and greater acceleration can be achieved without backlash or excessive friction. However, an important disadvantage of linear motor system is its high power loss and heating up of motor and neighboring machine components on operation. For the application of the linear motors to precision machine tools an effective cooling method and thermal optimizing measures are required. In this paper presents an investigation into a thermal behavior of linear motor cooling plate. FVM employed to analyze the thermal behavior of the linear motor cooling plate, using the ANSYS-CFX.

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A Study on the Structural Design of Linear Motor System (리니어모터 시스템 구조설계에 관한 연구)

  • Eun I.E.;Lee C.M.;Hwang Y.K.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.1059-1063
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    • 2005
  • Development of a feed drive-system with high speed, positioning accuracy and thrust has been an important issue in modern automation systems and machine tools. Linear motors can be used as an efficient system to achieve such technical demands. By eliminating mechanical transmission mechanisms such as ball screw or rack-pinion, much higher speeds and greater acceleration can be achieved without backlash or excessive friction. However, due to great power loss and magnetic attraction of the linear motors heating and deflection problems occur. Therefore, it is necessary to design strong structure, cooling device with high efficiency and light weight construction in designing stage of linear motors. This paper presents an investigation into a structural design of linear motor system. In this research, a new concept of moving table with high stiffness and of cooling plate is also introduced. Structure analyses are performed by using a commercial code ANSYS in order to evaluate the design safety.

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