24 2, pp. 108~116, 2014 http://dx.doi.org/10.5050/ksnve.2013.24.2.108 ISSN 1598-2785(Print), ISSN 2287-5476(Online) The Development and Application of Sound Quality Index for the Improving Luxury Sound Quality of Road Vehicle Power Window System * ** ** *** Seonghyeon Kim, Dong Chul Park, Hyeonho Jo, Weonchan Sung and Yeon June Kang (Received November 12, 2013 ; Revised February 6, 2014 ; Accepted February 6, 2014) Key Words : Window Lift System( ), Sound Quality Analysis( ), Subjective Evaluation( ), Multiple Linear Regression Analysis( ), Sound Quality Index( ) ABSTRACT With the increasing the importance of emotional quality of vehicle, the sound quality of systems with electric motor components has become increasingly important. Electric motors are used for windows, seats, sun roof, mirrors, steering columns, windshield wiper and climate control blowers, etc. In this paper, a study was conducted to identify sound quality factors that contribute to customer s satisfaction and preference of the window lift system. Jury test for subjective evaluation was carried out and sound quality index was developed. Averaged sound pressure level and sharpness were significant factors when glass moves down. Also, maximum loudness at stop section and averaged loudness were significant factor when glass moves up. Next, noise source identification was carried out using beam forming method during glass transferred section and impulsive noise at stop section. Several improvement methods were applied using the source identification result. And finally, the degree of sound quality improvement was judged using sound quality index. NVH(noise, vibration and harshness),,.,, (sound quality). (powetrain),, Corresponding Author ; Member, Hyundai Motor Company E-mail : dc.park@hyundai.com Tel : +82-31-368-0877, Fax : +82-31-368-1381 * Member, Hyundai Motor Company ** Member, Department of Mechanical Engineering, Graduate School, Seoul National University *** Member, School of Mechanical & Aerospace Engineering, Seoul National University # A part of this paper was presented at the KSNVE 2013 Annual Autumn Conference Recommended by Editor Don Chool Lee c The Korean Society for Noise and Vibration Engineering 108
(sound quality index) (1,2). (road noise) (wind noise) (driving sound).,,., (window lift), (central door lock), (sun roof), (windshield wiper), (power seat), (outside mirror).. (glass) (3~7).. Penfold (8) 12 (fluctuation feeling) (whine). 300 Hz~2500 Hz (band passed loudness) (linear regression model). Zhang (9) (semantic differential method) (principle component analysis). (gentle), (quite) (intensity) 1, (steady) (motor tone) (pitch variation) 2 (sharp) (sharpness) 3. (pleasantness) (Zwicker s parameter) (roughness).,.. (subjective), (objective). (beam forming method) (sound field visualization)... Fig. 1 (10). Fig. 2. (pulley) (drum).. (glass run).. (mounting). (gradient). 109
Fig. 1 The schematic of window lift system in door module(electric power and manual window type) Fig. 3 Overall sound pressure level profile (a) Door module Fig. 4 Time vs. Frequency characteristics Fig. 4.. /. (b) Window regulator Fig. 2 Module panel and window regulator of typical door module structure. (tonal noise). Fig. 3 11. (binaural effect) HEAD acoustics SQuadriga (binaural) (11).. HEAD acoustics ArtemiS S/W. 110
Fig. 5 Test program using the rating method (a) Window open (12). (1) Primary Effect: (2) Recency Effect: (3) Central Judgment Effect: (4) Ceiling Effect: /. (12). (box-plot) (outlier).., 80 %. Fig. 6 () 95 % (bar). (b) Window close Fig. 6 Result of subjective test on open and close condition 20~30 20 HEAD acoustics PEQ V (playback system).. Ricardo RISA S/W (rating method) 10. Fig. 5. HEAD Acoustics ArtemiS 12 S/W (sound quality metric) (correlation). (Kutosis), (crest factor), (hearing model impulsiveness). (time-varient) DIN 45631/A1.. 111
(a) Subjective rating vs. averaged SPL (b) Subjective rating vs. averaged sharpness Fig. 7 Scattering plot of averaged SPL and sharpness at transfer section open condition. Figs. 7~8. Average.. (1). y x x R 2 = β0 + β1 1+ β1 2 +, (1) y, x 1, x 2. y,. R 2 (goodness of fit) 0 1 1 (13). Minitab ver. 16 (stepwise regression (a) Subjective rating vs. averaged loudness (b) Subjective rating vs. max. loudness Fig. 8 Scattering plot of averaged loudness at transfer section and max. loudness at stop section close condition Table 1 Coefficients of the regression model open condition Model Unstandardized Coefficient Standardized Constant 27.16 3.75 Avg. SPL -0.35 0.08 Avg. sharpness -1.66 0.77 analysis). / 2 R 2 80 %, 93 %. (ANOVA). p-value 0.001, 0.000 95 %. Tables 1, 2. 112
Table 2 Coefficients of the regression model close condition Coefficient Model Unstandardized Standardized Constant 14.24 0.88 Max. Loudness -0.03 0.02 Avg. Loudness -0.84 0.07..,.,. (a) Glass open (b) Glass close Fig. 9 Sound visualization for motor booming noise... 0.5 khz~4 khz SM Instrument 30. 1.5 khz 2.0 khz. 2.0 khz. Fig. 9, Fig. 10(a). (a) Glass open/close (b) Glass stop at end position Fig. 10 Sound visualization for friction noise (a) and impulse noise at end position (b). 113
(a) Appearance of window motor (a) Original (b) After improvement Fig. 12 Improvement result of motor noise (b) Configuration of DC brushed motor (14) Fig. 11 DC Motor for power window (SPL) ( ), ( )..,,. (1) DC, (brush) (commutator) (cogging torque), (amature),.,.. Fig. 11. Fig. 12 800 Hz. (2).. (rib). (foam). Fig. 13 0s~3s, 4 s~7 s 114
(a) Original. (2) 1.5 khz 2.0 khz. (3),.,. (b) After improvement Fig. 13 Improvement result for friction noise of high frequency region, motor tonal and impact noise Table 3 Sound quality index after applied modification Factor Differential value Avg. SPL - 3.7 db Avg. sharpness - 0.3 acum Index value + 1.8 score. 2 khz 7s. Table 3 1.8.. (1),, (1) Lee, J. K., Cho, T. H., Seo, D. W., Lim, Y. S. and Won, K. M., 2012, A Development of Sound Quality Index of an Intake and Exhaust System, Transactions of the Korean Society for Noise and Vibration Engineering, Vol. 22, No. 3, pp. 234~243. (2) Kwon, J. S., Kim, C. M., Kim, K. C. and Kim, J. T., 2011, Study on the Sound Quality Evaluation Method for the Vehicle Diesel Engine Noise, Transactions of the Korean Society for Noise and Vibration Engineering, Vol. 21, No. 10, pp. 883~889. (3) Friedman, J. and Ghidella, J., 2006, Using Model-based Design for Automotive Systems Engineering - Requirements Analysis of the Power Window Example, SAE Technical Paper 2006-01-1217. (4) Filley, M., 2006, Benefits of a New Concept Window Lift System in a Typically Constrained Door Environment, SAE Technical Paper 2006-01-1481. (5) Choby, D., Jager, G., Johnstone, J. and Fenelon, P., 2004, An Efficient Light Weight all Plastic Dual Rack and Pinion Window Lift Mechanism for Automotive Vehicles, SAE Technical Paper 2004-01-0007. (6) Kliffken, M., Becker, H., Lamm, H., Prüssel, H. et al., 2001, Obstacle Detection for Power Operated Window-Lift and Sunroof Actuation Systems, SAE Technical Paper 2001-01-0466. (7) Singh, K., 1999, Experimental Assessment of 115
Door Window Glass Smooth Operation And Tracking, SAE Technical Paper 1999-01-3161. (8) Penfold, J., 1997, Power Window Sound Quality - A Case Study, SAE Technical Paper 972017. (9) Zhang, L. and Vértiz, A., 1997, What Really Affect Customer Perception? - A Window Regulator Sound Quality Example, SAE Technical Paper 971909 (10) http://hdabob.com/windows.htm. (11) HEAD Acoustics Application Note, Binaural Measurement, Analysis and Playback, HEAD acoustics, http://www.head-acoustics.de/. (12) Klaus, G., 2010, Sound-Engineering im Automobilbereich, Chap. 4. (13) Kim, S. H. and Park, D. C., 2013, The Preference Study of Vehicle Warning Sound Considering the Sale Region and Personal Preference based on Psychoacoustics, Proceedings of the KSNVE Annual Spring Conference, pp. 122~129. (14) http://www.johnsonelectric.com/ Seonghyeon Kim received the B.S. and M.S. degrees in Mechanical Engineering from Hanyang University, Korea in 2004 and 2006, respectively. Currently, He is a senior research engineer at Hyundai Motor Company. His research focuses on vehicle sound quality and sound designing. Dong Chul Park received the B.S., M.S., Ph.D. degrees in Mechanical Design Engineering from Seoul National University, Korea in 1990, 1994, 1996, respectively. Currently, he is a research fellow at Hyundai Motor Company. His research focuses on vehicle sound quality and sound designing. Hyeonho Jo is an Ph.D. candidate at department of Mechanical and Aerospace Engineering in Seoul National University. He received his B.S. degree and Masters in Biosystems Engineering from Seoul National University in 2008 and 2010, respectively. His research areas are sound quality of industrial products and human aural perception. Weonchan Sung received B.S. degree in department of Mechanical Engineering in Hanyang University, Korea. He is now master course in department of Mechanical and Aerospace Engineering in Seoul National University, Korea. His research areas are Sound Quality of industrial products. Yeon June Kang is a professor at department of Mechanical and Aerospace Engineering in Seoul National University. He received his Ph.D. degree in Mechanical Engineering, Purdue University in 1994. His research areas are acoustical materials, automotive NVH and Sound Quality. 116