عنوان مقاله
دستگاه اندازه گیری سایش مستمر در آزمایش پایداری کلاچ خیس
فهرست مطالب
چکیده
مقدمه
مواد و روش ها
نتایج و بحث
نتیجه گیری
بخشی از مقاله
پوشش کلاچ
سایش کلاچ را می توان به طور مستقیم به هم بسته در ضخامت سیستم کلاچ خورد رو مرتبط دانست که می تواند از طریق اندازه گیری فاصله با پیستون در طول تعامل بدست بیاید. در منحنی شکل 6 دیده می شود که افزایش اندازه گیری در فاصله طی شده توسط پیستون در طول تعامل بیش از یک سری آزمون را در 25000 درگیری با هر نقطه از نمودار نشان می دهد . محور خطا نیز نشان دهنده انحراف استاندارد از ضخامت کلاچ بوده که با استفاده از میکرومتر با میانگین تغییر ضخامت به عنوان مقدار متوسط اندازه گیری می شود .
کلمات کلیدی:
Apparatus for continuous wear measurements during wet clutch durability tests Niklas Lingestena, Pär Marklunda,∗, Erik Höglunda, Martin Lunda, Joakim Lundinb, Rikard Mäki b a Division of Machine Elements, Luleå University of Technology, 971 87 Luleå, Sweden b Volvo Construction Equipment, Eskilstuna, Sweden a r t i c l e i n f o Article history: Received 23 May 2011 Received in revised form 14 February 2012 Accepted 21 February 2012 Available online 1 March 2012 Keywords: Wet clutch Wear Test bench Tribology Temperature measurement a b s t r a c t Wet clutches are used in many applications today such as automatic transmissions and limited slip differentials in cars as well as in heavy duty equipment such as wheel loaders. The present study is concerned with the wear and engagement behavior of wet clutches in the latter type of application. A test rig is developed in which the wet clutch engagement is monitored during an arbitrary number of test cycles. This rig has many similarities with the SAE #2 test rig in that they are both inertia type test rigs. However, the test rig presented here has several original parts from heavy duty equipment in production incorporated into it. The data collection includes a continuous measurement of the position of the piston used to apply force on the clutch pack in addition to the separator disc temperatures, hydraulic actuating pressure and torque transfer characteristics. The measurements of the piston position can then be related to the clutch wear during a long test series. © 2012 Published by Elsevier B.V. 1. Introduction Wet clutches have been critical components of automatic transmissions and limited slip differentials for several decades. However, phenomena in the clutch such as shudder and torque transfer failure has prompted investigations into wet clutch behavior. The two main methods used are computer simulations of the clutch behavior and experimental investigations using wet clutch test rigs. One of the most commonly reported methods used in wet clutch studies is the SAE #2 test rig which mainly functions as an inertia dynamometer where a flywheel is accelerated to accumulate energy whereupon a clutch is engaged to brake the flywheel. This test setup allows for measurement of torque transfer properties and friction characteristics for a wide variety of operating conditions and has been used extensively in research [1–3] and is also frequently used in industry. A similar test rig was developed by Holgerson [4] with the addition of allowing a contribution by a driving torque to the energy input to the clutch. In Holgerson’s test rig the clutch temperature was measured using an infrared thermometer, allowing for investigations on the influence of temperature on clutch behavior. For the limited slip differential application, however, the SAE #2 test rig is not suitable due to the continuous slip conditions of the clutch. Investigations into the clutch characteristics of limited slip differentials has been performed by Mäki et al. [5] and Ivanovic ∗ Corresponding author. Tel.: +46 920 492415; fax: +46 920 49 13 99. E-mail address: par.marklund@ltu.se (P. Marklund). et al. [6] in test rigs designed specifically for this application. The temperature in the clutch separator discs was measured through the use of thermocouples which allowed for investigation of the dependence of friction characteristics on temperature. Marklund et al.[7] used pin-on-disc method to develop a friction model for purposes of simulating wet clutch behavior. However, this approach is not suitable for studying clutch wear in particular as demonstrated by Ost et al. [8] nor is it suited for investigations of clutch aging in general. This is in part because of the large difference in contact area to system size ratio in this setup as compared to the clutch. Deterioration of clutch performance during service life is an important issue, limiting the development towards smaller and more efficient clutches. The clutch aging can be divided into two categories. One is lubricant aging as investigated by Berglund et al. [9] for the limited slip clutch. The second is friction material aging, including for example wear. Glazing as described by Newcomb et al. [10] could be described as a combination of the two where the lubricant degrades due to the high temperature in the interface forming smooth layer on the friction material surface. Wear in particular will severely affect the clutch control since the thickness of clutch discs should be considered when construction clutch control algorithms and might affect the friction characteristics. Wear of wet clutch friction discs has been investigated before using a few different techniques. The early stages of wear has been studied by many authors [3,11,12] in terms of the real contact area between friction material and steel disc. For purposes of long term durability of a clutch, the wear of the full clutch pack is more interesting as it has more of an effect on how the engagement must be 0043-1648/$ – see front matter © 2012 Published by Elsevier B.V.
