Cải tiến mô tơ quay siêu nhỏ và ứng dụng trong hệ thống bánh răng

JOliRNAL OF SCIENCE & TECHNOLOGV * No 88 - 2012 DEVELOPMENT OF THE MICRO ROTATIONAL MOTOR AND APPLICATION IN GEARING SYSTEMS CAI TIEN MO TO QUAY Sl&U N H VA LTNG DUNG TRONG H$ THQNG BANH RANG P/iant Hong Phuc Hanoi University of Science and Teclmology Received February 21, 2012; accepted May 5, 2012 ABSTRACT This paper pmsents the design and fabrication of a Micm Rotational Motor (MRM) and its appticatk3ns in which four micm mtational comb-drive acluators (MRCA) are used to drive the rotor thmugh ratchet teeth For the geanng system, a ring with ratchet teeth inside and involute teeth outside will be used Instead of the mtor The novel design of the anti-reverse and anti-gap structure overcomes the gap pmblem after deep reactive ion etching of silicon The actuators and gearing system have been fabricated by using a SOI wafer with the device layer of 30 pm and tested for periormance They am driven by a periodic voltage (Vpp = 80 V) with diffemnt frequencies ranging fmm Hz to 30 Hz In this range, the angular velocity of the ratchet ring was proportional with the frequency and matched very well with theoretical calculation TOM TAT Bdi bdo ndy trinh bdy qud trinh thiit ki vd ehi tao md ta quay kich thu&c micmmet (MRM) vd ung dung cua nd tmng dd bdn bd kich ho^t rdng luge dugc su dung di din ddng rd to nh& cdc rdng cdc Tmng hd thdng bdnh rdng vdnh rdng v&i phin rdng cdc bdn vd rdng thdn khai bdn ngodi s§ duge sir dung Thidt ki m&i /g cda ciu true chdng ddo vd chdng khe h& giOp khic phuc cdc khe smh sau chi t$o Cdc bd kich boat vd h$ thdng bdnh rdng duge chi t^o bdng vat lidu Silicon v6i bi ddy Idm viec 30 micmmet va da dugc kiim tra ho^t ddng lai didn dp xoay chieu 80 V, ddi tin so tu din 30 Hz Tmng gi&i h^n ddi tin ndy v$n tic gde cOa vdnh rang Id ly Id thudn v&i tin s6 dan vd khd sdt v&i tinh todn ly' thuyit I INTRODUCTION Electrostatic comb-drive actuators and their applications are important components in MEMS Since the first reports on micromachined comb actuator by Tang el al [1],[2], there has been a substantial number of researches on comb-drive actuators and their applications The electrostatic effect of comb actuators were well investigated analytically [3], hi [4],[5], research on micro-machined comb actuator focuses on the structure design lo obtain large displacement and high stability Comb actuators have been used in many applications, e.g., as optical switches [6], as drivers for micro gear trains [7],[8] or to move a shuttle forward in a linear inchworm motor [9] The design and fabrication of micro rotational motor have been a topic of many recent publications Sniegowski el al used two sets of linear comb actuators to drive the output gear [7],[8] The linear motion of comb actuator has been converted to rotary motion via linkages pinned into the output gear Kim developed a rotary motor by inchworm motion The rotor is wrapped by two opposite belts which are connected to piezoelectric actuators [10] Sammoura demonstrated a rotary inchworm motor using four gap-closing actuators to rotate a free moving rotor [11] Advantages of these types are high angular velocity and low driving voltage However they required sophisticated control systems In this paper, the electrostatic comb-drive actuators (MRCA) will be used to drive the rotor through ratchet mechanism The microratchet was first used in MEMS by Sandia National Laboratories [12].[13] and b\ the author [14],[15] The advantages of this system are balch fabrication, simple configuration and control JOURNAL OF SCIENCE & TECHNOLOGY * No 88 - 2012 CONFIGURATION AND WORKING PRINCIPLE OF THE MICRO ROTATIONAL MOTOR Fig shows the motor which consists of four MRCAs four anti-reverse mechanisms and an outer ratchet ring Ratchet ring can rotate in one direction due to reciprocal motion of the rolalional comb actuators through ratchet teeth and an anti-reverse mechanism Structure of Ihe rotational comb actuator is shown in Fig The MRCA here refers to the electrostatic comb-drive actuator that the movement of its fingers is rotational around an clastic point (enlargement at Ihe bottom in Fig 7) Kalchet rack, with suitably shaped teeth as saw I i -'cted with movable comb fingers througn :.|,, •; > ,.i drive the outer ratchet ring in one direction n\i