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侧装式少齿差传动卷扬机设计

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侧装少齿差传动卷扬机设计

中文摘要VI

外文摘要VII

前言VIII

1 绪论1

　　　1.1 卷扬机国内外现状和发展趋势与研究的主攻方向1

　　　1.2 少齿差行星齿轮传动计算现状及发展4

　　　1.3 设计思路及方案论证5

2 主要设计参数的确定6

　　　2.1 卷扬机工作级别的确定7

　　　2.2 钢丝绳直径的选取7

　　　2.3 卷筒计算直径的确定8

　　　2.4 电机的选择与传动比的计算8

3 渐开线少齿差减速装置的设计9

　　　3.1 少齿差传动原理9

　　　3.2 齿轮齿数的确定10

　　　3.3 齿轮模数的确定10

　　　3.4 齿轮基本参数的确定13

　　　3.5 传动内部结构的选定与设计16

　　　3.6 轴的设计18

4 部分零件的校核23

　　　4.1 少齿差行星传动受力分析24

　　　4.2 销轴的强度校核26

　　　4.3 输出轴的强度校核27

　　　4.4 键的校核29

　　　4.5 轴承的校核30

5 卷筒主要尺寸的确定32

　　　5.1 卷筒节径、边缘直径和容绳宽度的确定32

　　　5.2 卷筒厚度与绳槽尺寸的确定32

6 结束语34

参考文献35

致谢36

附录37

[摘要]渐开线少齿差传动卷扬机是诸多传动形式卷扬机中的一种。利用少齿差传动机构的优越性可改进和提高建筑机械等设备的传动结构技术性能，将渐开线少齿差行星齿轮传动应用于建筑卷扬机的动力传输系统，可以减小机构尺寸，提高传动质量，同时它的传动比大、承载能力大、寿命长，也降低了制造成本。但是在渐开线少齿差内啮合传动中,由于内齿轮和外齿轮的齿数差少,在切削和装配时常常会产生各种干涉,以致造成报废。因此,为了保证内啮合传动的正常运转,设计时要满足几个条件，主要的两个限制条件是，即要保证不发生齿廓重迭干涉和啮合率不小于1。少齿差内啮合的设计非常烦琐,尤其是齿廓重迭干涉验算最为麻烦，这也是解决设计问题的核心所在。在设计过程中多次变换变位系数和齿顶高系数以满足条件。

　　　本文主要对少齿差行星齿轮传动的设计计算进行了说明。其中包括工作原理、参数选择、几何计算等。并根据结构尺寸设计零件、选择标准件，然后再进行强度或者寿命校核计算。

　　　[关键词] 卷扬机；渐开线少齿差传动；齿廓重迭干涉；少齿差内啮合

设计思路及方案论证

　　　设计卷扬机首先要确定卷筒直径，因为它直接影响卷扬机的结构及转速。如果卷筒直径大，会使卷扬的涨、抱闸系统的直径增大，其产生的力矩大大增加；还使卷扬机的转速下降，达不到设计要求。卷筒直径确定后，可以进行卷扬机的转速计算。

　　　接下来就是减速装置设计计算（渐开线少齿差行星齿轮减速装置设计，齿轮传动设计）。而减速器的设计关键在于掌握渐开线少齿差行星传动的原理：少齿差行星传动原理如图3所示，当带曲柄的输入轴旋转时，空套在曲柄上的行星轮Z1反向旋转（Z2-Z1）/Z1转，然后通过输出轴输出，去速比是I＝－Z1/(Z2-Z1),负号代表旋转反向相反。

卷扬机工作级别的确定

　　　由于卷扬机设计要求为：每日两班间歇工作，工作寿命为10年；因此根据相关文献查得其利用等级为级；又根据相关公式确定起载荷谱系数为0.25，因此

根据相关设计手册确定起工作级别为级

2.2 钢丝绳直径的选取

　　　根据已知条件（额定拉力10KN和提升速度20米/分）对钢丝绳进行选取。

　　　目前在工业化国家，对钢丝绳直径的选择普遍采用选择系数法。国际标准ISO308（钢丝绳的选择）也推荐采用此方法。

钢丝绳的直径不应小于下式计算的最小直径

式中 s——钢丝绳最大工作拉力

　　　c—— 钢丝绳选择系数，它与机构的工作级别、钢丝绳是否旋转以及吊运物品的性质等因素有关。目前，建筑卷扬机还没有此系数的气体规定。可参考《建筑卷扬机设计》一书中的表3－96进行选取。部分数据在下表已给出。

　　　据查表取得c＝0.0953，由已知s=10kN故算得：

0.0953×＝9.53

　　　可取钢丝绳直径为d=11，

表1 钢丝绳选择系数

卷扬机工作级别 t值（mm/

　　　　　吊运一般物资

　　　　　不旋转钢丝绳可自由旋转钢丝绳

钢丝绳的平均抗拉强度极限（MPa）

1570177019602150245015701770

A10.07100.06700.0600.0750

A20.07500.07100.06700.06700.0800

A30.08500.08000.07500.09000.0850

A4~A60.09700.0950.09530.10630.1060

A7~A80.11870.11870.11870.13330.1333

2.3 卷筒计算直径的确定

　　　由绕在卷筒上的钢丝绳圈中心算起的卷筒直径,称为卷筒的计算直径。为保证钢丝绳有足够的使用寿命，卷筒的计算直径不易太小。

（mm）

　　　值根据机构的工作级别由《建筑机械设计》中表3－11选取，

　　　据查表取得＝19，则有：

＝209mm

　　　可取=240mm。

　　　卷扬机又称绞车，是由动力驱动的卷筒通过挠性件(钢丝绳、链条)起升、运移重物的起重装置。它结构简单，使用方便，广泛应用于建筑、安装、运输等部门的拽引和起重作业。扬机按驱动方式可分为人力驱动和动力驱动两大类。人力驱动型有：绞盘、手摇卷扬机等。用在缺乏电源或使用电源不便的地方。动力驱动型主要是电力驱动。卷扬机按拽引速度可分快速和慢速两种。快速卷扬机一般拽引速度为30-50m/min，多用于建筑工地。慢速卷扬机拽引速度为7-15m/min，主要用于设备安装作业。

　　　此次设计的是侧装式少齿差传动卷扬机，它是以少齿差行星齿轮传动为传输系统。少齿差行星传动是渐开线少齿差行星传动的简称,它采用的是渐开线齿形。摆线针轮减速器和谐波减速器也属于少齿差行星传动原理,但摆线针轮减速器用的是摆线齿形,谐波减速器用的是三角形齿形(也有用渐开线齿形代) 。另外像ZX 型混凝土振动器用的是摩擦轮,但其增速原理也是少齿差行星传动。由于它们都有专门名称,所以一般所讲的少齿差行星传动是专指渐开线少齿差行星传动而言的。随着现代工业的发展,机械化和自动化水平的不断提高,各工业部门需要大量减速器,并要求减速器的体积小、重量轻、传动比大、效率高、承载能力大、运转可靠以及寿命长等。减速器的种类虽然很多,但普通的圆柱齿轮减速器的体积大、结构笨重;普通的蜗轮减速器在大传动比时,效率较低;摆线针轮减速器虽能满足以上提出的要求,但其成本高,需要专用设备制造。而利用少齿差行星传动可降低成本。

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内容简介：: 原文说明原文说明的内容是：文章阐述了电机的工作原理、发展过程、以及伺服电机的工作控制原理。并且举例说明了伺服电机所适用的场合。题名Servomotors Elements and Applications作者 NEWMARKER来源佳工机电网How Does a Motor Work?An electric motor converts electricity into mechanical motion. Electric motors are used in household appliances, electric fans, remote-controlled toys, and in thousands of other applications. The electric motor grew out of one of the earliest discoveries in electric scienceAragos rotations. In 1824, Francois Arago discovered that a magnetic needle suspended over a copper disk would rotate when the disc was spun. The next year, computer pioneer Charles Babbage and astronomer John Herschel showed that the action could be reversed: spinning a more powerful magnet above the copper disk would spin the copper disc. Then, in 1831, Michael Faraday conducted experiments that helped explain why this took place. While this laid the groundwork for the electric motor, it was another half century before electric motors were doing useful work. Over the next few decades many inventors made improved devices for turning electricity into motion. One of these was Hippolyte Pixiis 1832 improvement called the commutator, which switched the flow of current between two or more sets of stationary electromagnets to keep a motor continuously rotating. Thomas Davenport was the first to build an electric motor large enough to be used in industry, and he was also the first to seek a patent on a motor. Soon electric motors were being used for such things as transportation. Moritz-Hermann De Jacobi used an electric motor on a boat on the Neva River, and Charles G. Page used one to build a small locomotive. After the appearance of commercial electric power systems in the 1880s, larger electric motors were possible. Edison encouraged the use of electric motors in industrial applications and designed several new electric motors for that purpose. An important change came in the later 1880s and 1890s, when electric power companies began considering the switch to alternating current. Alternating current was perfect for the distribution of electric power over long distances, and it worked well with the Edison electric lamp, but no practical AC motor existed until the works of Galileo Ferraris in Italy and Nikola Tesla in the United States. Teslas contributions are remembered today more than Ferraris in part because Tesla was subsequently hired by the Westinghouse corporation, which used his patents along with many others to become one of the major producers of electric equipment. With a suitable AC motor available, AC power took off. It is still in use today.ServomotorServomotors are available as AC or DC motors. Early servomotors were generally DC motors because the only type of control for large currents was through SCRs for many years. As transistors became capable of controlling larger currents and switching the large currents at higher frequencies, the AC servomotor became used more often. Early servomotors were specifically designed for servo amplifiers. Today a class of motors is designed for applications that may use a servo amplifier or a variable-frequency controller, which means that a motor may be used in a servo system in one application, and used in a variable-frequency drive in another application. Some companies also call any closed-loop system that does not use a stepper motor a servo system, so it is possible for a simple AC induction motor that is connected to a velocity controller to be called a servomotor.Some changes that must be made to any motor that is designed as a servomotor includes the ability to operate at a range of speeds without overheating, the ability to operate at zero speed and retain sufficient torque to hold a load in position, and the ability to operate at very low speeds for long periods of time without overheating. Older-type motors have cooling fans that are connected directly to the motor shaft. When the motor runs at slow speed, the fan does not move enough air to cool the motor. Newer motors have a separate fan mounted so it will provide optimum cooling air. This fan is powered by a constant voltage source so that it will turn at maximum RPM at all times regardless of the speed of the servomotor. One of the most usable types of motors in servo systems is the permanent magnet (PM) type motor. The voltage for the field winding of the permanent magnet type motor can be AC voltage or DC voltage. The permanent magnet-type motor is similar to other PM type motors presented previously. Figure-1 shows a cutaway picture of a PM motor and Fig.-2 shows a cutaway diagram of a PM motor. From the picture and diagram you can see the housing, rotor and stator all look very similar to the previous type PM motors. The major difference with this type of motor is that it may have gear reduction to be able to move larger loads quickly from a stand still position. This type of PM motor also has an encoder or resolver built into the motor housing. This ensures that the device will accurately indicate the position or velocity of the motor shaft.FIGURE 1-1 Typical PM servomotorsFIGURE 1-2 Cutaway picture of a permanent magnet servomotorBrushless ServomotorsThe brushless servomotor is designed to operate without brushes. This means that the commutation that the brushes provided must now be provided electronically. Electronic commutation is provided by switching transistors on and off at appropriate times. Figure 1-3 shows three examples of the voltage and current waveforms that are sent to the brushless servomotor. Figure 1-4 shows an example of the three windings of the brushless servomotor. The main point about the brushless servomotor is that it can be powered by either ac voltage or dc voltage. FIGURE 1-3 (a) Trapezoidal input voltage and square wave current waveforms. (b) Sinusoidal input voltage and sinusoidal voltage and square wave output voltage waveforms. (c) Sinusoidal input voltage and sinusoidal current waveforms. This has become the most popular type of brushless servomotor control.Figure 1-4 shows three sets of transistors that are similar to the transistors in the output stage of the variable-frequency drive. In Fig. l-4a the transistors are connected to the three windings of the motor in a similar manner as in the variable-frequency drive. In Fig. l-4b the diagram of the waveforms for the output of the transistors is shown as three separate sinusoidal waves. The waveforms for the control circuit for the base of each transistor are shown in Fig. l-4c. Figure l-4d shows the back EMF for the drive waveforms. FIGURE 11-86 (a) Transistors connected to the three windings of the brushless servomotor. (b) Waveforms of the three separate voltages that are used to power the three motor windings. (c) Waveforms of the signals used to control the transistor sequence that provides the waveforms for the previous diagram, (d) Waveform of the overall back EMFServomotor Controllers Servomotor controllers have become more than just amplifiers for a servomotor. Today servomotor controllers must be able to make a number of decisions and provide a means to receive signals from external sensors and controls in the system, and send signals to host controllers and PLCs that may interface with the servo system. Figure 1-5 shows a picture of several servomotors and their amplifiers. The components in this picture look similar to a variety of other types of motors and controllers. FIGURE 1-5 Example servomotors and amplifiersFigure 1-6 shows a diagram of the servomotor controller so that you can see some of the differences from other types of motor controllers. The controller in this diagram is for a DC servomotor. The controller has three ports that bring signals in or send signals out of the controller. The power supply, servomotor, and tachometer are connected to port P3 at the bottom of the controller. You can see that the supply voltage is 115-volt AC single phase. A main disconnect is connected in series with the LI wire. The LI and N lines supply power to an isolation step-down transformer. The secondary voltage of the trans-former can be any voltage between 20 and 85 volts. The controller is grounded at terminal 8. You should remember that the ground at this point is only used to provide protection against short circuits for all metal parts in the system. The servomotor is connected to the controller at terminals 4 and 5. Terminal 5 is + and terminal 4 is - . Terminal 3 provides a ground for the shield of the wires that connect the motor and the controller. The tachometer is connected to terminals 1 and 2. Terminal 2 is + and terminal 1 is - . The shield for this cable is grounded to the motor case. The wires connected to this port will be larger than wires connected to the other ports, since they must be capable of carrying the larger motor current. If the motor uses an external cooling fan, it will be connected through this port. In most cases the cooling fan will be powered by single-phase or three-phase AC voltage that remains at a constant level, such as 110 volts AC or 240 volts AC. FIGURE 1-6 Diagram of a servo controller. This diagram shows the digital (on-off) signals and the analog signals that are sent to the controller, and the signals the controller sends back to the host controller or PLC.The command signal is sent to the controller through port PI. The terminals for the command signal are 1 and 2. Terminal 1 is + and terminal 2 is - . This signal is a type signal, which means that it is not grounded or does not share a ground potential with any other part of the circuit. Several additional auxiliary signals are also connected through port 1. These signals include inhibit (INH), which is used to disable the drive from an external controller, and forward and reverse commands (FAC and RAC), which tell the controller to send the voltage to the motor so that it will rotate in the forward or reverse direction. In some applications, the forward maximum travel limit switch and reverse maximum travel limit switch are connected so that if the machine travel moves to the extreme position so that it touches the overtravel limit switch, it will automatically energize the drive to begin travel in the opposite direction. Port PI also provides several digital output signals that can be used to send fault signals or other information such as drive running back to a host controller or PLC. Port PI basically is the interface for all digital (on-off) signals. Port P2 is the interface for analog (0-max) signals. Typical signals on this bus include motor current and motor velocity signals that are sent from the servo controller back to the host or PLC where they can be used in verification logic to ensure the controller is sending the correct information to the motor. Input signals from the host or PLC can also be sent to the controller to set maximum current and velocity for the drive. In newer digital drives, these values are controlled by drive parameters that are programmed into the drive. PWM Servo Amplifier The PWM servo amplifier is used on small-size servo applications that use DC brush-type servomotors. Figure 1-7 shows a diagram for this type of amplifier. From the diagram you can see that single-phase AC power is provided to the amplifier as the supply at the lower left part of the diagram. The AC voltage is rectified and sent to the output section of the drive that is shown in the top right comer of the diagram. The output section of the drive uses four IGBTs to create the pulse-width modulation waveform. The IGBTs are connected so that they provide 30-120 volts DC and up to 30 A to the brush-type DC servo-motor. The polarity of the motor is indicated in the diagram. The remaining circuits show a variety of fault circuits in the middle of the diagram that originate from the fault logic board and provide an output signal at the bottom of the diagram. You should notice that the fault output signals include overvoltage, overtemperature, and overcurrent. A fourth signal is identified as SSO (system status output), which indicates the status of the system as faulted anytime a fault has occurred. A jumper is used to set the SSO signal as an open collector output with a logic level 1 indicating the drive is ready, or as a normally closed relay indicating the drive is ready. The input terminals at the bottom right part of the diagram are used to enable or inhibit the drive, and to select forward amplifier clamp (FAC) or reverse amplifier clamp (RAC). The inhibit signal is used as a control signal, since it inhibits the output stage of the amplifier if it is high. The FAC and RAC signals limit the current in the opposite direction to 5%. The input signals are shown in the diagram at the upper left side. The VCS (velocity command signal) requires a +VCS and a -VCS signal to provide the differential signal. FIGURE 1-7 Diagram of a pulse-width modulator (PWM) amplifier with a brush-type DC servomotorApplications for Servo Amplifiers and Motors You will get a better idea of how servomotors and amplifiers operate if you see some typical applications. Figure 1-8 shows an example of a servomotor used to control a press feed. In this application sheet material is fed into a press where it is cut off to length with a knife blade or sheer. The sheet material may have a logo or other advertisement that must line up registration marks with the cut-off point. In this application the speed and position of the sheet material must be synchronized with the correct cut-off point. The feed-back sensor could be an encoder or resolver that is coupled with a photoelectric sensor to determine the location of the registration mark. An operator panel is provided so that the operator can jog the system for maintenance to the blades, or when loading a new roll of material. The operator panel could also be used to call up parameters for the drive that correspond to each type of material that is used. The system could also be integrated with a programmable controller or other type of controller and the operator panel could be used to select the correct cutoff points for each type of material or product that is run. FIGURE 1-8 Application of a servomotor controlling the speed of material as it enters a press for cutting pieces to size.An Example of a Servo Controlled In-Line Bottle-Filling ApplicationA second application is shown in Fig. 1-9. In this application multiple filling heads line up with bottles as they move along a continuous line. Each of the filling heads must match up with a bottle and track the bottle while it is moving. Product is dispensed as the nozzles move with the bottles. In this application 10 nozzles are mounted on a carriage that is driven by a ball-screw mechanism. The ball-screw mechanism is also called a lead screw. When the motor turns the shaft of the ball screw, the carriage will move horizontally along the length of the ball-screw shaft. This movement will be smooth so that each of the nozzles can dispense product into the bottles with little spillage. The servo drive system utilizes a positioning drive controller with software that allows the position and velocity to be tracked as the conveyor line moves the bottles. A master encoder tracks the bottles as they move along the conveyor line. An auger feed system is also used just prior to the point where the bottles enter the filling station. The auger causes a specific amount of space to be set between each bottle as it enters the filling station. The bottles may be packed tightly as they approach the auger, but as they pass through the auger their space is set exactly so that the necks of the bottles will match the spacing of the filling nozzles. A detector is also in conjunction with the dispensing system to ensure that no product is dispensed from a nozzle if a bottle is missing or large spaces appear between bottles. FIGURE 1-9 Application of a beverage-filling station controlled by a servomotorThe servo drive system compares the position of the bottles from the master encoder to the feedback signal that indicates the position of the filling carriage that is mounted to the ball screw. The servo drive amplifier will increase or decrease the speed of the ball-screw mechanism so that the nozzles will match the speed of the bottles exactly. An Example of a Servo Controlled Precision Auger Filling System A third application for a servo system is provided in Fig. 1-10. In this application a large filling tank is used to fill containers as they pass along a conveyor line. The material that is dispensed into the containers can be a single material fill or it can be one of several materials added to a container that is dumped into a mixer for a blending operation. Since the amount of material that is dispensed into the container must be accurately weighed and metered into the box, an auger that is controlled by a servo system is used. The feedback sensor for this system can be a weighing system such as the load cell discussed in earlier chapters. The command signal can come from a programmable controller or the operator can enter it manually by selecting a recipe from the operators terminal. The amount of material can be different from recipe to recipe. FIGURE 1-10 Application of a precision auger filling station controlled by a servomotor.The speed of the auger can be adjusted so that it runs at high speed when the container is first being filled, and the speed can be slowed to a point where the final grams of material can be metered precisely as the container is filled to the proper point. As the price of material increases, precision filling equipment can provide savings as well as quality in the amount of product used in the recipe. An Example of a Label Application Using Servomotors The fourth application has a servomotor controlling the speed of a label-feed mechanism that pulls preprinted labels from a roll and applies them to packages as they move on a continuous conveyor system past the labeling mechanism. The feedback signals are provided by an encoder that indicates the location of the conveyor, tach generator that indicates the speed of the conveyor, and a sensor that indicates the registration mark on each label. The servo positioning system is controlled by a microprocessor that sets the error signal, and the servo amplifier that provides power signals to the servomotor. This application is shown in Fig. 1-11. FIGURE 1-11 Example of a labeling application controlled by a servomotorAn Example of a Random Timing Infeed System Controlled by a Servomotor The fifth application is presented in Fig. 1-12, and it shows a series of packaging equipment that operates as three separate machines. The timing cycle of each station of the packaging system is independent from the others. The packaging system consists of an infeed conveyor, a positioning conveyor, and a wrapping station. The infeed conveyor and the wrapping station are mechanically connected so that they run at the same speed. The position of the packages on the wrapping station must be strictly controlled so that the packages do not become too close to each other. A piece of metal called a flight is connected to the wrapping station conveyor at specific points to ensure each package stays in position. A sensor is mounted at the beginning of the positioning conveyor to determine the front edge of the package when it starts to move onto the positioning conveyor. A second sensor is positioned at the bottom of the packaging conveyor to detect the flights. Both of these signals from the sensors are sent to the servomotor to provide information so the servo can adjust the speed of the positioning conveyor so that each package aligns with one of the flights as it moves onto the packaging conveyor. This application shows that the servo positioning controller can handle a variety of different signals from more than one sensor because the controller uses a microprocessor. FIGURE 1-12 Example of a packaging system with random timing functions controlled by a servo-motor.译文伺服电机原理及应用电机是如何工作的？电动机是将电能转换成机械运动,电机用在家用电器,电动风扇,遥控玩具等各种使用场合电机起源于早期电学上的一个发现- Arago转动.在1824年, Francois Arago发现悬浮在铜盘上的磁针,在铜盘转动时也跟着转动.第二年,计算机先驱Charles Babbage和天文学家John Herschel向人们展示上述运动可以相逆的:转动一块位于铜盘上方较强的磁铁时,铜盘也转动.在1831年, Michael Faraday通过试验来解释这一现象发生的原因.在电机实际运用前,半个多世纪来做这些电机些基础研究过了几十年后,许多发明家不断改进发明将电能转换成机械能.其中一个就是1832 Hippolyte Pixii改进了之后称为换向器的发明.它通过改变位于两个或更多的固定电磁石电流方向,以维持一台电机连续运转. Thomas Davenport是第一个制造出在工业中使用的电机.并是第一个对电机申请专利的.不久电机被用作诸如交通运输等场合. Moritz-Hermann De Jacobi将一台电机安装在涅瓦河上的一条船上. Charles G. Page用电机做了一台小型机车.伴随着19世纪80年代商业性电力供应系统出现,制造出更大的电机也变得有可能. Edison鼓励在工业中便用电机,并且设计了几一些为工业使用兵新型电机在19世纪80年代到90年代发生了一个重大变化,电力公司开始考虑转成交流电.交流适合于长距离传输.并且在Edison的电灯上工作的很好,但是没有实际的交流电机存在,直到意大利的Galileo Ferraris和美国的Nikola Tesla. 在今天人们认为Tesla的贡献比Ferraris大部分原因是前者后来受雇于西屋公司,这家公司应用了他自己的及其他人的专利,成了为电气设备一个主要的生产者.随着交流电机成为可能,交流电力的发展,交流电机一直使用到现在。伺服电机伺服电机包括交流电机和直流电机。早期的伺服电机通常是直流电机，因为那时只有通过可控硅才能控制大电流。由于晶体管能够控制大电流,并在更高的频率转换大电流，交流电机使用越来越广泛。早期的伺服电机是特别为伺服放大器设计的。如今电机设计则可应用于伺服放大器或变频控制器。这意味着，电机一方面可以用于伺服系统，另一方面可以用于变频驱动。一些公司把不使用步进电机的环闭系统称为伺服系统，因此与调速器相连接的交流异步电机也可以被称作为伺服电机。伺服电机还有些地方需要改进，包括在额定转速内运行不过热，电机静止时仍能保证足够的扭矩去承受负载在规定的位置，以及超低速长时间转动不过热。旧型电机冷却风扇是直接连在接电机主轴上。当电机工作在低速时，风扇不能产生足够的气流来冷却电机。新一代的电机拥有独立的风扇安装在电机上，所以能提供足够的冷却气流。这个风扇动力来自一个恒压源所以可以使风扇能始终运行在最高转速下，而不管伺服电机的转速如何。在所有伺服电机中，最实用的是永磁电动机。永磁电机的绕组电压可以是交流也可以是直流.这类永磁电机同以前的永磁电机类似。图1-1显示的是一台普通永磁电机的剖示图。图1-2展示的是伺服永磁电机的剖示图。从图中可以看出，新的电机在轴承室，转子，定子上同以前的电机类似。主要的区别只在于这种新类型的电机可以较大的负载从静止状态动作。这类永磁电机同样有一个编码器或变压器被放置在电机内部。这个可以确保设备能更精确的显示电机轴的位置或速度。图1-1 典型永磁电机图1-2剖视图永磁伺服电机无刷伺服电机无刷伺服电机可以无碳刷运行，这就意味着它的换向现在需要由电子完成而不是由机械碳刷来完成。电子换向由晶体管以某种周期方式开关来实现的。图1-3显示三条输入到无刷伺服电机的电压和电流波形。图1-4显示一台三相绕组的无刷伺服电机，这种无刷伺服电机的主要特点是可以交流或直流电源驱动。图1-3(a)输入电压、电流方波梯形波表(b)正弦电压和正弦输入电压和方波输出电压波型(c)正玄输入电压和正弦电流波形这已经成为最流行的无刷式伺服控制图1-3展示三种电压波形来驱动无刷伺服电机。图1-3a展示梯形反电动势电压，方波电流输入，图1-3b显示为一正弦波输入电压和一方波电流波形，图-3c显示一正弦波办公设备电压放一正弦波电流波形,正弦波电压和正弦波电流波形是无刷伺服电机最常用的驱动。图1-4（a）晶体管三相绕阻无刷伺服电机。（b）三相绕阻电机使用三个独立的电压波形。（c）波形信号用来控制晶体管的波形序列。（d）反电势波形。图1-4展示三组晶体管,它同变频驱动的输出端很相似.在图1-4a，连接到电机三相绕阻的晶体管同变频驱动基本相同。图1-4b晶体管输出波形图，它是由三组独立的正弦波形组成。图1-4c是输入到每个晶体管的控制端的波形。图1-4d显示驱动波形的反电势。伺服电机控制器伺服电机控制器使一台伺服电机不只是用于放大器功能。今天的伺服电机控制器既要能做一定量的判断，也要提供一种方法能接受外部传感器和内部控制的信号，同时也可以在主控制器，PLCS和伺服系统数据交换。图1-5展示一些伺服电机与放大器。从图中看,这些同其它类型的电机和控制器比较相似。图1-5 伺服电机与放大器图1-6显示一张伺服电机控制器的图,你可以从中看出与其它类型电机的不同之处。图中的控制器用于直流伺服电机。输入电源，伺服电机及转速计连接到控制器底部的P3端口。可以看出输入电源为115V单相交流电。一个主断路器串联在L1线上。由L1和N经过的电源经过一个隔离的降压变压器.变压器的次级电压可是介于20到85伏的之间的任意电压。控制器通过引脚8接地.你应该记得在这点接地只是用来对系统的金属部份提供短路保护。图1-6 伺服控制图（此图显示将数字信号和模拟信号送到控制器，再由信号控制器将信号送回给所在的主控制器或可编程控制器）伺服电机边接控制器的4脚和5脚。其中5脚是+，4脚是-。3脚是对电机和控制器提供一种屏蔽接地保护。转速计连接到引脚1和引脚2，其中脚2是+，脚1是-。屏蔽线缆同电机外壳连接.连接到这个端口的引线应该比同其它端口的引线要粗，因为他们承受更大的电机电流。如果电机使用额外的散热风扇，它也应该连接到这个端口上，在绝大部分场合，散热风扇由一常规的110V或240V的单相或三相交流电供电。控制信号通过P1端口送到控制器.控制信号的引脚是1和2,其中1是+,2是-.这是一种非接地常规的信号,同电路中其它部分不共享接地,一些附加的辅助信号也连接到P1。这些信号包括约束，如可以通过外部控制器来使驱动失效。正反转命令，如要求控制器给电机通电，使电机按顺时针方向或逆时针方向转动。在某些场合，最大正转行程极限开关和最大反转行程开关连接到一起，以便当机器运行到极限位置时触发另一状态的开关。这时将自动的以反方向重新驱动。P1端品也提供一些数字输出信号,一通常用于送出一些故障信号或其它信息,诸如正在运转,到主控制器或PLC.P1端口主要是数字(1-0)信号的端口。P2端口是逻辑信口的窗口，总线上的典型信号包括

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