2. solenoid

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2. solenoid

  1. 1. Institut Kemahiran MARA Jasin, Melaka INFORMATION SHEETPROGRAMME : A14 - SIJIL TEKNOLOGI BAIKPULIH BADAN KENDERAANSESSION : SEMESTER : 2 TAB 2042 / BASIC AUTOMOTIVECODE/COURSE : SHEET NO : A14/M03/IS06 ELECTRICAL AND ELECTRONICLECTURER : MD HAFIZI BIN MOHAMAD WEEK : 2TOPIC : M03 CIRCUIT AND TERMINALS 03.01 WIRE HARNESS 03.02 COLOR CODING 03.03 TERMINALS AND SOCKETSUB-TOPIC : 03.04 RELAYS, SWITCHERS AND SOLENOIDS 03.05 EARTH 03.06 POWER WINDOW Pelajar-pelajar mesti boleh: 1. Terangkan mengenai medan magnet. 2. Terangkan mengenai elektromagnet.LEARNINGOUTCOME : 3. Terangkan mengenai solenoid. 4. Terangkan operasi solenoid. 5. Nyatakan kegunaan solenoid.TAJUK : KEMAGNETANTUJUANLitar elektrik amat penting dalam sistem elektrikal kenderaan. Ia membolehkan komponen-komponen elektrik kenderaan berfungsi dengan sempurna. Pelbagai kaedah digunakan untukmenyampaikan sesuatau tindakan bagi menggerakkan komponen elektrik kenderaan. Penghasilanelektromagnet amat penting dalam menggerakkan satu unit kerja. Kertas penerangan ini akanmenerangkan maksud tersebut. 1
  2. 2. PENERANGANMEDAN MAGNETMedan magnet ialah kawasan disekitar satu magnet atau satu pengalir yang membawa arus dimana satu daya magnet akan bertindak pada satu bahan magnet. Magnet mempunyai dua kutubiaitu kutub selatan dan kutub utara. Arus yang mengalir melalui satu pengalir akan menghasilkansatu medan magnet disekitar pengalir tersebut. Arus yang mengalir akan menghasilkan medanmagnet apabila melalui suatu pengalir. Medan magnet yang mengalir adalah sepusat mengelilingipengalir. Medan magnet terdiri daripada garisan magnet atau fluks magnet. Gambarajah 6.1 Medan Magnet Gambarajah 6.2 Medan oleh dawai yang membawa arus 2
  3. 3. Gambarajah 6.3 Medan Magnet pada pengalirELEKTROMAGNETMedan magnet yang dihasilkan oleh aliran arus melalui dawai boleh dikuatkan lagi denganmenebat dawai dan melilitkannya pada teras besi. Medan magnet akan tertumpu di teras besi dania akan menjadi magnet selagi arus mengalir melalui dawai itu. Elektromagnet merupakan satumedan magnet yang terjadi hasil daripada pergerakkan arus yang melalui pengalir yang dililitkanpada satu teras besi. Ia merupakan satu medan magnet sementara. Apabila arus elektrikdiputuskan maka medan magnet tersebut akan hilang. Gamabarajah 6.4 Medan magnet yang terhasil disekeliling dawai pengalir 3
  4. 4. SOLENOIDSolenoid merupakan satu gegelung pengalir yang panjang berbentuk seperti selinder yangbertindak sebagai alat elektromagnet di mana akan menghasilkan medan magnet apabila arusmengalir melaluinya. Solenoid selalunya digunakan untuk menukarkan tenaga elektrik kepadatenaga mekanikal yang bertindak seperti suis. Solenoid adalah penting kerana ianya bolehmenghasilkan medan magnet terkawal dan juga sebagai elektromagnet.Solenoid merupakan komponen elektromagnet yang boleh menggerakkan logam plunger besaratau teras. Pergerakkan teras ini boleh digunakan untuk menutup sesentuh elektrik yang besaratau menggerakkan sesuatu bahagian untuk tujuan penyambungan. Selain itu juga pergerakkan inimungkin digunakan untuk mengunci pintu kereta atau menutup beberapa penyambungan elektrik.Dalam automotif, starter solenoid digunakan untuk melengkapkan penyambungan bateri ke litarmotor penghidup. Ia bertindak sebagai relay yang besar untuk menyambungkan arus yang tinggidalam litar. Ada juga starter solenoids yang menggerakkan starter gear bersambung denganflywheel ring gear untuk mengengkol enjin.Solenoid yang kecil boleh digunakan untuk mengawalengine throttle position dan kelajuan enjin. Gambarajah 6.5 Contoh solenoid 4
  5. 5. Gambarajah 6.5 Salah satu contoh penggunaan solenoidLihat gambarajah 6.5, menunjukkan contoh salah satu kegunaan solenoid. Arus elektrik akanmengalir melalui belitan solenoid dan menghasilkan medan magnet. Medan magnet ini akanmenolak teras ke dalam belitan menyebabkan teras akan bersentuh dengan titik sesentuh solenoidmenjadikan litar tertutup dan arus boleh mengalir. Apabila arus diputuskan daripada belitansolenoid, tindakakn spring akan membolehkan teras kembali pada kedudukan asalnya.OPERASI SOLENOIDSolenoid bagi penggunaan automotif terdiri daripada gegelung wayar pengalir (coil), field danplunger. Gegelung wayar pengalir mengandungi lilitan wayar tembaga yang mempunyai lilitan yangpadat serta tersusun. Apabila arus mengalir melalui gegelung wayar, satu medan magnet yangkuat akan terhasil disekeliling gegelung wayar. Medan magnet ini akan bergerak memasukibahagian tengah gegelung wayar sehingga membentuk lingkaran. Gambarajah 6.6. Medan magnet disekeliling gegelung pengalirGegelung pengalir ini akan ditempatkan di dalam perumah yang berbentuk selinder berlubang yangdiperbuat daripada bahan pengalir. Memandangkan medan magnet boleh bergerak dengan mudahmelepasi besi, perumah ini menambahkan kekuatan medan magnet. Plunger yang berbentuk bulatmempunyai muncung bercas positif di satu bahagian. Apabila dimasukkan ke bahagian tengah 5
  6. 6. gegelung wayar tersebut akan menyebabkan medan magnet semakin bertambah. Bahagian bawahplunger yang leper dan bercas negatif akan menghasilkan kawasan yang besar membolehkanmedan magnet bertambah kuat. Gambarajah 6.7 Medan magnet bertambah kuat apabila gegelung wayar dimasukkan kedalam perumah besiGambarajah 6.8 Medah magnet semakin bertambah kuat apabila dimasukkan teras besi ditengah- tengah gegelung besi.Apabila diletakkan bebanan dihadapan plunger ini akan menyebabkan solenoid itu menolak danapabila diletakkan bebanan dibelakang solenoid ianya akan menarik.Gambarajah 6.9 Pengerakan plunger yang menarik dan menolak bebanan hasil daripada terjadinya medan magnet. 6
  7. 7. PENGGUNAAN SOLENOIDa. Electromechanical solenoidsElectromechanical solenoids consist of an electromagnetically inductive coil, wound around amovable steel or iron slug (termed the armature). The coil is shaped such that the armature can bemoved in and out of the center, altering the coils inductance and thereby becoming anelectromagnet. The armature is used to provide a mechanical force to some mechanism (such ascontrolling a pneumatic valve). Although typically weak over anything but very short distances,solenoids may be controlled directly by a controller circuit, and thus have very low reaction times.The force applied to the armature is proportional to the change in inductance of the coil with respectto the change in position of the armature, and the current flowing through the coil (see Faradayslaw of induction). The force applied to the armature will always move the armature in a directionthat increases the coils inductance.Electromechanical solenoids are commonly seen in electronic paintball markers, pinball machines,dot matrix printers and fuel injectors.The rotary solenoid is an electromechanical device used to rotate a ratcheting mechanism whenpower is applied. These were used in the 1950s for rotary snap-switch automation inelectromechanical controls. Repeated actuation of the rotary solenoid advances the snap-switchforward one position. Two rotary actuators on opposite ends of the rotary snap-switch shaft, canadvance or reverse the switch position.The rotary solenoid has a similar appearance to a linear solenoid, except that the core is mountedin the center of a large flat disk, with two or three inclined grooves cut into the underside of the disk.These grooves align with slots on the solenoid body, with ball bearings in the grooves.When the solenoid is activated, the core is drawn into the coil, and the disk rotates on the ballbearings in the grooves as it moves towards the coil body. When power is removed, a spring on thedisk rotates it back to its starting position, also pulling the core out of the coil.The rotary solenoid was invented in 1944 by George H. Leland, of Dayton, Ohio, to provide a morereliable and shock/vibration tolerant release mechanism for air-dropped bombs. Previously usedlinear (axial) solenoids were prone to inadvertent releases. U.S. Patent number 2,496,880describes the electromagnet and inclined raceways that are the basis of the invention. Lelandsengineer, Earl W. Kerman, was instrumental in developing a compatible bomb release shackle thatincorporated the rotary solenoid. Bomb shackles of this type are found in a B-29 aircraft fuselageon display at the National Museum of the USAF in Dayton, Ohio. Solenoids of this variety continueto be used in countless modern applications, and are still manufactured under Lelands originalbrand "Ledex", now owned by Johnson Electric.b. Rotary voice coilThis is a rotational version of a solenoid. Typically the fixed magnet is on the outside, and the coilpart moves in an arc controlled by the current flow through the coils. Rotary voice coils are widelyemployed in devices such as disk drives. 7
  8. 8. c. Pneumatic solenoid valvesA pneumatic solenoid valve is a switch for routing air to any pneumatic device, usually an actuator,allowing a relatively small signal to control a large device. It is also the interface between electroniccontrollers and pneumatic systems.d. Hydraulic solenoid valvesHydraulic solenoid valves are in general similar to pneumatic solenoid valves except that theycontrol the flow of hydraulic fluid (oil), often at around 3000 psi (210 bar, 21 MPa, 21 MN/m²).Hydraulic machinery uses solenoids to control the flow of oil to rams or actuators to (for instance)bend sheets of titanium in aerospace manufacturing. Solenoid-controlled valves are often used inirrigation systems, where a relatively weak solenoid opens and closes a small pilot valve, which inturn activates the main valve by applying fluid pressure to a piston or diaphragm that ismechanically coupled to the main valve. Solenoids are also in everyday household items such aswashing machines to control the flow and amount of water into the drum.Transmission solenoids control fluid flow through an automatic transmission and are typicallyinstalled in the transmission valve body.e. Automobile starter solenoidIn a car or truck, the starter solenoid is part of an automobile starting system. The starter solenoidreceives a large electric current from the car battery and a small electric current from the ignitionswitch. When the ignition switch is turned on (i.e. when the key is turned to start the car), the smallelectric current forces the starter solenoid to close a pair of heavy contacts, thus relaying the largeelectric current to the starter motor.Starter solenoids can also be built into the starter itself, often visible on the outside of the starter. Ifa starter solenoid receives insufficient power from the battery, it will fail to start the motor, and mayproduce a rapid clicking or clacking sound. This can be caused by a low or dead battery, bycorroded or loose connections in the cable, or by a broken or damaged positive (red) cable from thebattery. Any of these will result in some power to the solenoid, but not enough to hold the heavycontacts closed, so the starter motor itself never spins, and the engine does not start. 8
  9. 9. Gambarajah 6.10 Solenoid bagi motor penghidup kenderaan. KESIMPULAN EXERCISE 1. Terangkan secara ringkas mengenai elektromagnet. 2. Terangkan secara ringkas mengenai solenoid. 3. Nyatakan aplikasi solenoid pada kejuruteraan. REFERENCE1. Akademi Saga, Basic Electrical & electronic System Information Sheet, Shah Alam, Selangor: Edaran Otomobil Nasional Berhad.2. Akademi Saga, Basic Electrical & electronic System Work Sheet, Shah Alam, Selangor: Edaran Otomobil Nasional Berhad.3. Tom Denton, Automobile Electrical & Electronic Systems4. DTAF IKM Jasin, Information Sheet Auto-Electric5. Toyota Service Training 1989, Fundamentals of Electricity, Vol 14(Step 2), Toyota Motor Corporation.6. V.A.W. Hillier1986, Fundamentals of Automotive Electronics, Croydon College: Stanley Thornes Ltd. System7. Automotif Electrical/electronic System8. James E.Duffy 1998, Auto Electricity and Electronics Technology : The Goodheart-Willcox Company, Inc. 9
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