Bir doğru akım motorunun mekanik ve akustik titreşim özelliklerinin tayini ve iyileştirilmesi
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Date
2005-06-22
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Uludağ Üniversitesi
Abstract
Gerek mekanik sistemlerin tasarım sürecindeki gelişmeler, gerekse giderek daralan sağlık, çevre ve güvenlik kriterleri bakımından gürültü ve titreşim kontrolü; günümüzde büyük önem kazanmış ve başlı başına bilim dalı haline gelmiştir. Bu bağlamda, elektrikli ev aletlerinde, taşıt donanımlarında ve diğer pek çok makinede kullanıcının dayanım sınırlarını aşmayacak, dikkatini dağıtmayacak ya da konsantrasyonunu bozmayacak gürültü düzeyleri istenmektedir ve bu taleplere uyulması bir kalite göstergesi olarak algılanmaktadır. Bu çalışmada benzer bir amaca hizmet etmek için gerçekleştirilmiştir. Ülkemiz de üretilen ve oto cam sileceği mekanizmalarında kullanılan bu doğru akım motorunun belirli frekansta yoğunlaşan gürültüsünün nedenleri araştırılmıştır. Bu amaçla bilgisayar ortamında sanal darbe testleri yapılmış, ölçümle bulunan gürültü düzeyleri ile modal analiz sonuçları mukayese edilerek muhtemel gürültü kaynaklan kestirilmeye çalışılmıştır. Bu çalışmalar esnasında LMS firmasının Virtual Lab. 4B ve Altair firmasının Altair Hypermesh yazılımlarından ve çeşitli transdüserler ve donanımdan yararlanılmış tır. Elektrik motorlarında gürültü, genel olarak elektromanyetik, aerodinamik ve mekanik olmak üzere üç farklı orijinde olmakla beraber, bu çalışmalarda söz konusu problemin mekanik kaynaklı olduğu anlaşılmıştır. Önlem olarak, rotor balanslama işle minin daha dar toleranslarda gerçekleştirilmesi ve ikincil olarak da mekanik titreşimlerin yapıya yayılma noktası olan yatak burcunun gözden geçirilmesi önerilmiştir.
Both the developments in the design process of mechanical systems and the criteria being more and more strict for health and environment have made noise and vibration control very important and an engineering discipline. In this context, today the noise levels in many mechanical systems such as home appliances, automotive equipments etc are desired to be very low, such that tolerable exposure limits of users must not be exceeded. In fact, these kinds of requirements have already been considered as a significant indication of quality. Consequently, improvements of vibro-acoustic properties of mechanical systems seem to be one of most important design tasks for manufacturers. The present work is also concerned with examining and improving modal and acoustical properties of a DC motor used to drive windshield wiper system of a vehicle. The possible causes of the noise produced by this DC motor at a certain frequency have been investigated by using computational and experimental methods. To this end, virtual impact tests have been carried out in the computer environment and the numerical results in this way have been compared with the noise levels experimentally obtained to determine possible noise sources in the motor. During this study, the ip% software Virtual Lab. 4B of the LMS and the Altair Hypermesh and several transducers have been utilized. Although the noise in electrical motors has mainly electromagnetic, aerodynamic and mechanical origins, it has been concluded from this investigation that the problem under study is mechanically originated. As a measure, the restriction of rotor balancing tolerances and a closer mechanical examination of the bush used for bearing the rotor info* the back cover regarding its assembling conditions have been proposed.
Both the developments in the design process of mechanical systems and the criteria being more and more strict for health and environment have made noise and vibration control very important and an engineering discipline. In this context, today the noise levels in many mechanical systems such as home appliances, automotive equipments etc are desired to be very low, such that tolerable exposure limits of users must not be exceeded. In fact, these kinds of requirements have already been considered as a significant indication of quality. Consequently, improvements of vibro-acoustic properties of mechanical systems seem to be one of most important design tasks for manufacturers. The present work is also concerned with examining and improving modal and acoustical properties of a DC motor used to drive windshield wiper system of a vehicle. The possible causes of the noise produced by this DC motor at a certain frequency have been investigated by using computational and experimental methods. To this end, virtual impact tests have been carried out in the computer environment and the numerical results in this way have been compared with the noise levels experimentally obtained to determine possible noise sources in the motor. During this study, the ip% software Virtual Lab. 4B of the LMS and the Altair Hypermesh and several transducers have been utilized. Although the noise in electrical motors has mainly electromagnetic, aerodynamic and mechanical origins, it has been concluded from this investigation that the problem under study is mechanically originated. As a measure, the restriction of rotor balancing tolerances and a closer mechanical examination of the bush used for bearing the rotor info* the back cover regarding its assembling conditions have been proposed.
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Keywords
DC motor, Titreşim, Gürültü, Modal test, Öçüm yöntemleri, DC Motors, Vibration, Noise, Modal testing, Measurement methods
Citation
Sivrioğlu, O. (2005). Bir doğru akım motorunun mekanik ve akustik titreşim özelliklerinin tayini ve iyileştirilmesi. Yayınlanmamış yüksek lisans tezi. Uludağ Üniversitesi Fen Bilimleri Enstitüsü.