机械 外文翻译 外文文献 英文文献 采用表面微加工技术制造微型行星齿轮减速器.doc

1、附录一英文材料 MICRO PLANETARY REDUCTION GEAR USING SURFACE-MICROMACHININGAbstractA micro planetary gear mechanism featuring a high gear reduction ratio with compactness in size ispresented in this paper. SUMMiT V is employed for the fabrication method so that the redundancy of assembling parts is eliminat

2、ed. The design rules of which has also been checked. To make full use of the benefits of the surface- micro - machining, the planetary reduction gear is designed toward using the on-chip micro- engine. The expected gearreduction ratio is calculated and compared with the conventional chain gear mecha

3、nism. The microplanetary gear mechanism presented in this paper is expected to have 162:1 reduction ratio utilizing less space consumption. This is an order of magnitude higher than the previously reported design in a single reduction gear train.Keywords:MEMS, planetary gear, reduction gear surface-

4、micromachining, SUMMiT V processNomenclaturea sun gearb planet gearsc internal gear (fixed)d internal gear (rotary)n the number of units of gear trainD diameter of the pitch circleN number of teethP number of planets angular velocityIntroductionThe gear mechanisms in microelectro mechanical systems(

5、MEMS) are commonly expected to generate high torque in the confined micro-size systems. However, it is generally difficult for the micro-scale systems to have such a high torque without having multiple reduction systems.The design of the reduction gear drive based on a planetary paradox gear mechani

6、sm can increase the torque within a compact area, since the microplanetary gear system has an advantage of high reduction ratio per unit volume 1. However its mechanism is so complicated that relatively few attempts have been made to miniaturize the gear systems 2-3. Suzumori et al. 2 used the mecha

7、nical paradox planetary gear mechanism to drive a robot for 1-in pipes forward or backward. They employed a single motor to drive the gear mechanisms with high reduction ratio. Precise gear fabrication was enabled by micro wire electrical discharge machining (micro-EDM). These parts, however, should

8、 be assembled before the drive motor is attached to the gearbox. Takeuchi et. al. 3 also used micro-EDM to fabricate the micro planetary gears. They suggested special cermets or High Carbon Steel for possible materials. While the design can achieve a reduction ratio of 200, the gears should also be

9、assembled and motor driven.To enable the driving of the planetary gear by onchip means, Sandia Ultra- planar Multi-level MEMS Technology (SUMMiT-V) process 4 for planetary gear fabrication is adopted in this study. The SUMMiT-V process is the only foundry process available which utilizes four layers

10、 of releasable polysilicon, for a total of five layers (including a ground plane) 5. Due to this fact, it is frequently used in complicated gear mechanisms being driven by on-chip electrostatic actuators 5.However, in many cases, the microengines may not produce enough torque to drive the desired me

11、chanical load, since their electrostatic comb drives typically only generate a few tens of micronewtons of force. Fortunately, these engines can easily be driven at tens of thousands of revolutions per minutes. This makes it very feasible to trade speed for torque 7.Rodgers et al. 7 proposed two dua

12、l level gears with an overall gear reduction ratio of 12:1. Thus six of these modular transmission assemblies can have a 2,985,984:1 reduction ratio at the cost of the huge space.With the desire for size compactness and at the same time, high reduction ratios, the planetary gear system is presented

13、in this paper. It will be the first planetary gear mechanism using surface micromachining,to the authors knowledge. The principles of operations of the planetary gear mechanism, fabrication, and the expected performance of the planetary gear systems are described in this paper.Principles of operatio

14、nAn alternative way of using gears to transmit torque is to make one or more gears, i.e., planetary gears, rotate outside of one gear, i.e. sun gear. Most planetary reduction gears, at conventional size, are used as well-known compact mechanical power transmission systems 1. The schematic of the pla

15、netary gear system employed is shown in FigureSince SUMMiT V designs are laid out using AutoCAD 2000, the Figure 1 is generated automatically from the lay out masks (Appendix 1). One unit of the planetary gear system is composed of six gears: one sun gear, a, three planetary gears, b, one fixed ring

16、 gear, c, one rotating ring gear, d, and one output gear. The number of teeth for each gear is different from one another except among the planetary gears. An input gear is the sun gear, a, driven by the arm connected to the micro-engine. The rotating ring gear, d, is served as an output gear. For e

17、xample, if the arm drives the sun gear in the clockwise direction, the planetary gears, b, will rotate counter-clockwise at their own axis and at the same time, those will rotate about the sun gear in clockwise direction resulting in planetary motion. Due to the relative motion between the planetary

18、 gears, b, and the fixed ring gear, c, the rotating ring gear, d, will rotate counterclockwise direction. This is so called a 3K mechanical paradox planetary gear 1.Fabrication procedure and test structuresThe features of the SUMMiT V process offer four levels of structural polysilicon layers and an

19、 electrical poly level, and also employ traditional integrated circuit processing techniques 4. The SUMMiT V technology is especially suitable for the gear mechanism. The planetary gear mechanism can be driven by the on-chip engine and thus is another reason of using the SUMMiT V process.Since the S

20、andia process is such a well-known procedure 5-7, only brief explanation is presented. Figure 2 represents the cross-sectional view of Figure 1, and also was generated from the AutoCAD layout masks (Appendix 1). The discontinuity in the cross-section is for the etch holes. The poly1 (gray) is used f

21、or the hubs and also patterned to make the fixed ring gear, i.e., c, the sun gear, i.e., a, the rotating ring gear, i.e., c, and the output gear is patterned in the poly2. Since the planetary gear needs to contact both the fixed ring and rotating ring gear, poly2 is added to poly3, where the gear te

22、eth are actually formed. The poly4 layer is used for the arm that drives the sun gear. After the release etch, the planetary gears will fall down so that those will engage both the ring gears.The figures for the test structures are presented in Appendix 2. Since the aim of this paper is to suggest a

23、 gear reduction mechanism, the planetary gear system is decomposed to several gear units to verify its performance. The first test structure is about the arm, which rotates the sun gear, connected to the on-chip engine. The angular velocity of the arm depends on the engine output speed. The second t

24、est structure describes the point at which the sun gear and planetary gears are engaged to the fixed ring gear. Because of the fact that the ring gear is fixed, the planetary gear is just transmitting the torque from the sun gear to the fixed ring gear without planet motion, e.g., rotating its own a

25、xis not around the sun gear. When the rotating ring gear is mounted on top of the fixed ring gear, i.e., the third test structure, the planetary gears begin to rotate around the sun gear so that the planet motion are enabled. Therefore, once one output gear is attached to the rotating ring gear, i.e

26、., the final test structure, the whole reduction unit is completed. Dismantling the planetary gear into three test structures allows the pinpointing of possible errors in the gear system.Solutions procedure and expected performanceThe reduction ratio is defined as the ratio between the angular veloc

27、ity of the driver gear and that of the driven gear. High reduction ratios indicate trading speed for torque. For example, a 10:1 gear reduction unit could increase torque an order of magnitude. Since the gears in the planetary system should be meshed to one another , the design of gear module should

28、 follow a restriction. For example, the number of teeth for the sun gear plus either that of the fixed ring gear or that of the rotating ring gear should be the multiple of the number of planets, P (equation 1). Equation 2, which represent the reduction ratio, should observe the equation 1 first. Th

29、e N is the number of the teeth for corresponding gear.Gears, a, b, c, d in the planetary gear system have a tooth module of 4 m, which is a comparable size of the current gear reduction units5, and the tooth numbers are 12, 29, 69, and 72 respectively. Therefore the overall reduction ratio is 162:1

30、from equation (2). Rodgers et al. 7 reported a 12:1 reduction unit using surface micromachining, which is less than order of magnitude for the gear reduction ratio of the planetary gear system. Although the reduction from Rodgers et al. 7 needs to be occupied in approximately 0.093 mm2, the planetar

31、y gear system only utilizes an area of approximately 0.076 mm2. Thus, this planetary reduction design can achieve an order of magnitude higher reduction ratio with less space. Since thereduction module is composed of several reduction units, the advantage of using a planetary gear system is self evi

32、dent in Figure 3.Figure 3 shows the comparison of reduction ratios between the proposed planetary gear mechanism i.e. 162n, and the Sandia gear system 7, i.e. 12n, as a function of the number of units, i.e., n. The ordinate is drawn in log scale so that the orders of magnitude differences between tw

33、o modules are evident. For example, in a module with five numbers of units, the reduction ratio difference between two is approximately six orders of magnitudes. Furthermore, the planetary gear system can save 8500 m2 in such a five unit reduction system.Conclusion and discussionsThe planetary gear

34、reduction system using surface-micromachining, driven by an on-chip engine, first appears in this paper within the authors knowledge. The single reduction unit can achieve an order of magnitude higher reduction ratio than that of the previous design. However, due to the surface friction, and the bac

35、klash, which is inevitable for the gear manufacturing process, the overall reduction ratio may be less than 162:1 in the real situation. Even though some loss might be expected in the real application, the overall reduction ratio should be order of magnitude higher and the space consumption is less

36、than the previous design 7.The authors learned a lot about the surfacemicromachining process during the project grant,and realized that a lot of the design needed to be revisited and corrected. This became prevalent when drawing the cross-sectional views of the design. Since the authors utilized the

37、 SUMMit V Advanced design Tools Software package and verified the design rules, the planetary gear layout is ready for fabrication. The authors hope that this planetary reduction unit will continue to be updated by successive researchers.AcknowledgementThe authors would acknowledge that discussions

38、with Prof. Kris Pister, Prof. Arun Majumdar, Ms. Karen Cheung, and Mr. Elliot Hui contributed to this work tremendously.References1. Hori, K., and Sato, A., “Micro-planetary reduction gear” Proc. IEEE 2nd Int. Symp. Micro Machine and Human Sciences, pp. 53- 60 (1991).2. Suzumori, K., Miyagawa, T., K

39、imura, M., and Hasegawa, Y., “Micro Inspection Robot for 1-in Pipes”, IEEE/ASME Trans. On Mechatronics, Vol. 4., No. 3, pp. 286-292 (1999).3. Takeuchi, H., Nakamura, K., Shimizu, N., and Shibaike, N., “Optimization of Mechanical Interface for a Practical Micro-Reducer”, Proc. IEEE 13th Int. Symp. Mi

40、cro Electro Mechanical Systems, pp. 170-175 (2000).4. Sandia National Laboratories, “Design Rules Design Rules”, MicroelectronicsDevelopment Laboratory, Version 0.8, (2000)5. Krygowask, T. W., Sniegowask, J. J., Rodgers, M. S., Montague, S., and Allen, J. J., “Infrastructure, Technology and Applicat

41、ions of Micro-Electro-Mechanical Systems (MEMS)”, Sensor Expo 1999 (1999).6. Sniegowski, J. J., Miller, S. L., LaVigne, G. F., Rodgers, M. S., and McWhorter, P. J., “Monolithic Geared-Mechanisms Driven by aPolysilicon Surface-Micromachined On-Chip Electrostatic Microengine”, Solid-State Sensor and A

42、ctuator Workshop, pp. 178-182, (1996).7. Rogers, M. S., Sniegowski, S. S., Miller, S., and LaVigne, G. F., “Designing and Operating Electrostatically Driven Microengines”, Proceedings of the 44th International Instrumentation Symposium, Reno, NV, May 3-7, pp. 56-65 (1998).Figure 1. The schematic of

43、the planetarygear mechanism generated from SUMMiT Vdesign layout softwareFigure 2. A schematic cross-section of the planetary gear system generated by SUMMiT-V technologyFigure 3. The comparison of reduction ratios as a function of the number of units中文翻译 采用表面微加工技术制造微型行星齿轮减速器摘要这篇文章论述了一种结构紧凑、传动比高的微型行

44、星齿轮减速机构。这种机构的加工方法采用桑迪亚国家实验室研发的过度平面的多极微机电系统技术去除整体结构的冗余部分，而且这种设计原理已经得到承认。为了充分利用表面微加工技术，我们在设计加工这种行星减速齿轮时，需要使用安装在芯片上的微电机。我们将计算这种齿轮预期的减速比，并把它与传统的链传动和齿轮传动相比较。在这篇论文中演示的微行星轮占用较少的空间，消耗较少的材料，减速比却有望达到162：1。这比以前的论文中设计的减速器的传动比要高的多，简直是一个神话。关键字：微机电 行星齿轮 减速器 表面微加工 过度平面的多极微机电系统的加工（简称为SUMMiT V）术语：a.太阳轮b.行星轮c.内齿圈（固定）d

45、.内齿圈（旋转）n.齿轮系组成单元的数目D.节圆的直径N.齿数P.行星轮的数目.角速度介绍在微机电系统中的齿轮结构通常希望用来在微小的体积内产生较大的扭矩。但是没有较大重量的减速器，往往是很难达到这样的目的。研究发现拥有微行星齿轮的减速机构能够在狭小的空间内增加扭矩，这好像有点自相矛盾。这是因为微行星齿轮系统能在每单位体积内产生更大的传动比。然而它的结构是如此的复杂，以至于我们很少尝试将齿轮系统微型化。Suzumori以及他的小组成员曾经用类似的行星齿轮结构来驱动一个机器人，并使它在直径为一寸的钢管里前后移动。他们利用一个马达来驱动高传动比的齿轮机构，通过微电线的放电加工技术能够实现这种齿轮机

46、构的精确加工。但是这些部件应该在装配驱动马达之前安装在齿轮箱上。Takeuchi 等人也用这种技术制造了微行星齿轮。他们建议用特殊的含陶合金和高碳钢作为最佳选择材料。当这种齿轮系统的传动比达到200的时候，才可以安装马达并使之驱动。为了实现用芯片的方法来实现行星齿轮的驱动，在研究中我们采用SUMMiT V方法来加工微行星齿轮。SUMMiT V过程是唯一可以实现对于总数为五层(其中一层为地平面)的硅中释放四层的铸造过程由于这个原因，它经常被用来通过安装在芯片上的电子执行器来驱动复杂的齿轮机构。然而, 在许多情形,微电机不可能提供充足的转力矩来驱动机械负荷,因为它们的静电梳的典型驱动只产生几十微牛

47、顿的力。幸运的是,这些引擎能容易地达到每分钟几万转的速度。这就使将转矩转化为速度变成是可行的。罗杰等人设计了二个传动比为12：1的双重的水平齿轮。如此六个这样的模组的传输集合在以占据极大的空间为代价的前提下可以达到2,985,984:1的传动比。为了达到结构紧凑，同时达到高传动比的目的少比, 行星齿轮系统将被作为研究对象。根据作者的认识，它将会是第一个使用表面微加工原理设计的行星齿轮结构。我们还将阐述行星齿轮的操作规则，加工过程和希望达到的行星齿轮系统的性能。操作原则使用齿轮传输转矩的其它可行的方法是将一个或者多个的齿轮,也就是, 行星齿轮,在另一个齿轮的外面旋转,也就是太阳轮。按照传统的尺寸

48、设计的行星齿轮减速器是使整体结构紧凑的常用的传输系统。图1是上述的行星齿轮的示意图。自从用AutoCAD设计SUMMiT V以来,图（1）可以通过软件自动产生(附1)。一个完整的行星齿轮系统是由六个齿轮组成的: 一个太阳齿轮 a，三个行星齿轮 b，一个固定的内齿圈 c,一个旋转的内齿圈 d,和一个输出齿轮 e。除了行星齿轮之外,每个齿轮的齿数都不相同。 太阳齿轮 a是输入齿轮，由与微引擎连接的机械手驱动。内齿圈 d,被视为输出齿轮。举例来说,如果机械手驱动太阳轮按照顺时针方向方向旋转, 那么行星轮 b, 将绕着它们自己的轴按照逆时针方向宣战，同时也将绕着太阳轮按照顺时针方向的方向旋转，这样就形

49、成了行星运动。 由于多个行星齿轮b和固定内齿圈c之间的运动相似，所以旋转的内齿圈d将按照逆时针方向旋转。这也被叫做3K行星齿轮。加工过程和结构测试SUMMiT V程序的特征体现了硅层结构、电解聚乙烯, 以及传统的集成电路处理等技术水平的四个层次。SUMMiT V技术尤其适应于齿轮机构。行星齿轮机构由芯片上的微引擎驱动，而且这也是采用SUMMiT V技术的另一个理由。因为桑迪亚程序是一款众所周知的程序 ,所以我们只简要的作些解释。图2是图 1的截面视图,也是由AutoCAD按照附录1设计产生的，其中截面中的不连续的部分是为了钻孔而设置的。聚乙烯1(灰色)用来制造轮毂以及固定的内齿圈c,太阳齿轮a,旋转的内齿圈 c,而输出齿轮是由聚乙烯2制造的。图 1.是由SUMMiT V设计软件产生的行星齿轮机构的视图附录 2是描述测试结构的图形。因为这篇文