• Title/Summary/Keyword: CVVL

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A Study on Reliability Compliance Test based on Thermal Fatigue Accelerated Test for CVVL BLDC Motor (CVVL BLDC 모터의 열피로 가속시험을 통한 수명보증시험 설계)

  • Lee, San-Hoon;Park, Sang-Wook;Kim, Min-Geiun;Seon, Han-Geol;Hong, Sung Ryeul;Han, Man-Seung
    • Journal of Applied Reliability
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    • v.15 no.4
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    • pp.241-247
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    • 2015
  • Purpose : The demand for higher fuel economy vehicles has helped develop fuel-efficient vehicles such as a CVVL called continuous variable valve lift. Existing CVVL has been applying DC type motor to control intake valve, but recently some car parts manufacturers have been developing a BLDC type CVVL motor for improvements of endurance performance. The purpose of this study is to find the potential failure mechanism of the CVVL BLDC moto in early stage of development based on the design properties and design the accelerated life test model. Methods : CVVL BLDC is consist of brushs, coil, magnetic, PCB, bearing and so on. Each component has a latent failure mechanism caused by temperature, humidity, vibration. By analysis result of the failure mechanism, thermal fatigue is the most important factor of a durability of CVVL BLDC motor. So, we designed a new accelerated life test model for guarantee of the CVVL BLDC motor. Results : A crack occurred on via hole in test using the conditions we designed, so we did change the design to avoid this failure. The via hole dimension is changed a little larger, as a result we achieve improvements in reliability of the CVVL BLDC motor. By applying various kinds and extreme level of stresses, we can find the operating limits of products. Conclusion : In thesis, We analyzed the failure mechanism of CVVL BLDC and designed an accelerated life test method to give a guarantee for reliability. Based on the test results, we could improve the reliability of developments by change of design.

Design of Worm Gear for CVVL Paired with ZK Worm and Involute Helical Gear (ZK 웜과 인볼류트 헬리컬기어로 결합된 CVVL용 웜기어 설계)

  • Sohn, Jonghyeon;Park, Nogill;Oh, Chunghan
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.1
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    • pp.77-84
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    • 2014
  • The worm gear is used in the motor drive system of automotive CVVL because of its compactness and self-locking ability. A ZK worm and an involute helical gear can be meshed in order to reduce production cost. However, the gearing is not suitable for the reliability and the NVH problem. To improve the dynamic performances, an optimal design process is considered. The transmission error is calculated theoretically and minimized with the several gear design parameters. An inequality condition such as the teeth interference elimination is added.

Numerical Analysis for Prediction of the Residual Gas Fraction, Volumetric Efficiency and Pumping Loss with Continuous Variable Valve Lift System in an SI Engine (가변밸브 작동기구를 적용한 가솔린 기관의 잔류가스분율, 체적효율, 펌핑손실 예측을 위한 해석적 연구)

  • Cho, Yong-Seok;Lee, Seang-Wock;Jang, Ik-Kyoo;Park, Jung-kwon;Yoon, Yu-Bin;Park, Young-Joon;Kim, Hyun-Chul;Na, Byung-Chul
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.2
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    • pp.7-13
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    • 2010
  • To satisfy the needs on fuel economy and engine performance, continuous variable valve lift systems are applying to engines. In the CVVL system, fuel economy can be improved by reducing pumping loss during the induction process, and engine performance can be also improved by controlling volumetric efficiency and the residual gas fraction. Because the residual gas fraction directly affects volumetric efficiency, engine performance, combustion efficiency and emissions in SI engines, controlling residual gas fraction is one of the important things in engine development process. This analysis investigates the residual gas fraction and volumetric efficiency with changes of intake valve lifts and intake valve timings. In this study, unsteady state solutions were solved during exhaust and induction processes. Results show variation of the residual gas fraction and volumetric efficiency by changing intake valve timing and lift. Decreasing intake valve lift leads to increase the residual gas fraction and to decrease volumetric efficiency.