机电-体化专业英语Unit 9

1、Introduction to MotorsPart I Technical and Practical Reading Passage A The Motor Basics (I) The function of the motor is to convert electrical energy to mechanical energy. Thus, the motor is also classified as an electromechanical device/machine.Basics of Electromagnetic ForcesElectromagnetic Force

2、The direction of magnetic flux produced by a permanent magnet is always from N-pole to S-pole. When a conductor is placed in a magnetic field and current flows in the conductor, the magnetic field and the current interact each other to produce force. The force is called Electromagnetic force (Fig. 9

3、-1). The flemings left hand rule determines the direction of the current, the magnetic force and the flux. Stretch the thumb, the index finger and the middle finger of your left hand as shown in Fig. 9-2. When the middle finger is the current and the index finger the magnetic flux, the direction of

4、the force is given by the thumb. Magnet field produced by currentThe magnetic fields produced by the current and the permanent magnets works to produce electromagnetic force. When the current flows in the conductor toward the reader, the magnetic field in the CCW direction will be produced around th

5、e current flow by the right-handed screw rule (Fig. 9-3). Interference of a line of magnetic force The magnetic fields produced by the current and the permanent magnets interfere each other (Fig. 9-4). The line of magnetic force distributed in the same direction acts to increase its strength, while

6、the flux distributed in the opposite direction acts to reduce its strength. Electromagnetic force production The line of magnetic force has a nature to return to the straight line by its tension like an elastic band. Thus, the conductor is forced to move from where the magnetic force is stronger to

7、where it is weaker (Fig. 9-5). Torque production Electromagnetic force is obtained from the equation;Fig. 9-6 illustrates the torque obtained when a single-turn conductor is placed in the magnetic filed. The torque produced by the single conductor is obtained from the equation; T(torque) F (force) R

8、 (distance from the center to conductor) Here, there are two conductors present; Principles of Motor Motion1. Place Permanent MagnetPlace permanent magnets so that different polarities face each other. Thus, a parallel magnetic field will be created (Fig. 9-7).2. Place ArmaturePlace the armature in

9、the parallel magnetic field and conduct magnetization to have N-polarity at and S-polarity at and .Then, the armature will start CW rotation due to magnetic attraction and repulsion (Fig. 9-8).3. Magnetize ArmatureWind the coil and flow the current so that the armature will be magnetized (Fig. 9-9).

10、4. To Keep Rotation To keep the armature running, the current direction should be changed so that the N-polarity stays at upper portion and S- polarity stays at under portion of the armature (Fig. 9-10). 5. Switch Current DirectionTo change the current direction, coil shall be connected to the metal

11、 strips (commutator) shaped as a cylinder divided into three (Fig. 9-11).6. Place BrushTo keep CW rotation, apply plus (+) voltage to the left and minus () to the right brush.If CCW rotation is required, apply minus () voltage to the left and plus (+)to the right brush, or reverse the polarity of th

12、e magnet (Fig. 9-12). Notes 1、Place the armature in the parallel magnetic field and conduct magnetization to have N-polarity at and S-polarity at and . 全句为祈使句；Place和conduct为并列结构。全句译为：在磁场的平行方向置入电枢，同时产生了磁化现象，处是N极、和处是S极。2、To keep the armature running, the current direction should be changed so that the

13、 N-polarity stays at upper portion and S- polarity stays at under portion of the armature.本句是结果状语从句。To keep the armature running置于居首为强调。本句译为：为了保持电枢旋转，应改变电流方向，这样N极总在电枢的上部，S极总在电枢的下部。1、The direction of magnetic flux is usually considered from S-pole to N-pole.2、The magnetic fields produced by the curre

14、nt and the magnetic flux works to produce permanent magnets.3、The line of magnetic force has a property to return to the oblique line by its tension.4、As you known, the torque is obtained when a single-turn conductor is put in the magnetic filed.5、If CCW rotation is required, use minus (+) voltage t

15、o the left and plus () to the right brush. EXERCISE 1 Mark the following statements with T (True) or F (False) according to the passage. (F)(F)(F)(T)(F)magnetic flux _ 电磁力3. permanent magnet _ _ 右手螺旋定则5. magnetic field _ _ 磁力线7. elastic band _ 直线 EXERCISE 2Translate the following phrases into Chines

16、e or English. 磁通electromagnetic force永久磁铁right-handed screw rule磁场 line of magnetic force松紧带straight linePassage B Sheet Metal Forming Function of Main Motor Parts1. Produce Magnet Field Black-colored portions are permanent magnets that maintain magnetic force, and are fixed to a motor-housing. The

17、motor-housing itself produces a magnetic circuit (a magnetic field) with a core (a green-colored portion) and the permanent magnets as a path for the magnetic force to flow (Fig. 9-13).2. Provide Current Current enters the motor from one of the terminals (a portion sticks out forward). It flows to a

18、 winding (an orange-colored portion) via brushes (a brown-colored portion) and a commutator, and goes out of the motor from the other terminal via the brushes and the commutator (Fig. 9-14). 3. Output by Rotation The current flows into the magnet field produced by the permanent magnets, and that pro

19、duces electromagnetic force. The commutator switches the direction of the current in exact timing to have continuous rotation. The output is pulled out through a shaft (Fig. 9-15). Explanation of Motor PartsList of terms on motor performanceTermSymbolUnitInputPWOutputPWMaximum outputP max.WVoltageVV

20、CurrentIANo-load currentI0AStall currentIsAEfficiency%Maximum efficiency max.%SpeedNr/minNo-load speedN0r/minTorqueTNm, gcmStall torqueTsNm, gcmGeneral Instructions for Use of Motors In handling motors, be sure to read these general instructions to ensure safe, secure, and correct use of the motors.

21、Warning 1. Do not insert a lead or motor terminal into a home outlet. You might get an electric shock from this. 2. When applying current, do not touch a live part such as a current-carrying terminal. You might get an electric shock from this. 3. When applying current, keep your hand or finger off a

22、 rotary part. Otherwise, you might get hurt. 4. DONT leave motor shaft locked while power is applied, as even a short-time lock-up may cause excess heat build up resulting in burning damage to the motor depending on its specifications. 5. Depending on motor operating state (mounted state, load, and

23、environmental temperature), the motor might generate excessive heat. Be careful not to burn yourself due to the heat. EXERCISE 3 Choose the best operation orders according to the information given. Stator B. Rotor C. Spring D. Permanent Magnets E. Windings BEDACS.P. Standard Pressure _2. SR Slant Ra

24、nge _3. SS Stainless Steel _4. ss Spindle Speed _5. S.S.C. Semi-steel Casting _ 6. ST Standard Temperature _ 7. st. c. Steel Casting _8. str. st. Structure Steel _ EXERCISE 4Abbreviations are very useful in practical work. Read them and then translate them into corresponding Chinese terms. 标准压斜距不锈钢主

25、轴转速半钢铸件标准温度钢铸件结构钢Part II Glance at Conventional Machine Tool Structures The following is the Vice Jaw Structures。 Motor Control Overview Explanations of the Motor Control Terms No.NameExplanation1AC-DC交流直流2IGBT CURRENT DRIVERS绝缘栅双极晶体管电流驱动器3AMPLIFERS 放大器4ADC模数转换器5CURRENT SENSORS电流传感器6DSP数字信号处理器7GAIN

26、SETTING RESISTORS增益设定电阻器8REFERENCES参考值9INDUSTRIAL (OPTIONAL)工业输入输出口（可选）10MOTOR电机11ENCODER/RESOLVER编码器/分解器12DAC数模转换器EXERCISE 5The following is the Vice Jaw. After reading them, you are required to choose the suitable words or phrases given below. Power supply Terminal box Bearing RotorDrive pulley Ce

27、ntrifugal switch Cooling fan Stator Part III Simulated WritingSection A Match Your SkillThe following is the Lathe Accessories, and you can understand the name of Inner Dial Caliper Gauge. Explanations of the Motor Terms No.NameExplanation1Magnets磁铁2Can罩3Shims垫片4Windings绕组5Armature电枢6Stack帧7Commutat

28、or换向器8Shaft轴9Timing Ring定时环10Springs弹簧11End Ball端球12Brushes电刷EXERCISE 6Complete the information by translating the part given in Chinese. Leeson Reversible Electric Motor 5 HP, 1740 RPM, Model# 131537 This Leeson heavy-duty single phase, open drip-proof motor turns at 1740 RPM and is electrically re

29、versible. NameDataHP5Rated RPM1,740Volts230Amps21 at 230 VoltsHertz60Motor Phase(s)SingleShank Diameter (in.)1 1/8Shank Length (in.)2 3/4Frame TypeNema 184TRotation DirectionCounter ClockwiseReversibleYesOpen Drip Proof HousingYesCapacitor StartYesCapacitor RunYesULRecognizedCSACertifiedSection B Ha

30、ve a TryThis section will help you to understand several forms of machining, and you can see the simple way a small part is produced. Internal OperationsTaping - An operation in which a tap enters the workpiece axially and cuts internal threads into an existing hole. The existing hole is typically d

31、rilled by the required tap drill size that will accommodate the desired tap. On a milling machine, the threads may be cut to a specified depth inside the hole (bottom tap) or the complete depth of a through hole (through tap). EXERCISE 7This section is to test your ability to Identifying following f

32、eatures of different operations. Bored chamfer Tapping (Milling machine) Tapped holeTapping (Milling machine) Tapped hole Bored chamfer Part IV Broaden Your Horizon - Practical Activity Mini Motor RepairSTEP 1: If you look at the end cap of the motor housing, you will see (4) metal corners bent at a

33、n angle to hold the end cap on. All you have to do is take your pliers and bend them in the opposite direction so that you can remove the end cap. Then use a flathead screwdriver to pry the end cap off (see Figure 1 4). STEP 2: Pull the center shaft out from the motor case (see Figure 5). STEP 3: Wi

34、th the end cap removed and separated from the shaft, use your Digital Ohm Meter to test both outside terminals to see if there is any resistance. If you find that there is Zero resistance at the terminals, then that would indicate that your circuit is closed when it should be open, this means your capacitor has a short in it. Locate the capacitor on the end cap. Use a pair of wire cutters to separate the connection, as shown in the photos. Be sure to position it so that it doesnt reconnect on accident. Use your Ohm Meter to retest both outside terminals again, and you should see that the circ