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BENI SETYA NUGRAHA, M.Pd. 1. Topik Minggu Lalu Proses Pembakaran (Normal, Knocking, Detonasi) Engine Operating Cycle Siklus 2 & 4 Tak (Pendahuluan) 2.

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Presentasi berjudul: "BENI SETYA NUGRAHA, M.Pd. 1. Topik Minggu Lalu Proses Pembakaran (Normal, Knocking, Detonasi) Engine Operating Cycle Siklus 2 & 4 Tak (Pendahuluan) 2."— Transcript presentasi:

1 BENI SETYA NUGRAHA, M.Pd. 1

2 Topik Minggu Lalu Proses Pembakaran (Normal, Knocking, Detonasi) Engine Operating Cycle Siklus 2 & 4 Tak (Pendahuluan) 2

3 3 Siklus Kerja Motor Bensin 4 Tak (Four stroke Spark Ignition (SI) Engine) Stroke 1:Fuel-air mixture introduced into cylinder through intake valve Stroke 2:Fuel-air mixture compressed Stroke 3:Combustion (roughly constant volume) occurs and product gases expand doing work Stroke 4:Product gases pushed out of the cylinder through the exhaust valve Compression Stroke Power Stroke Exhaust Stroke A I R Combustion Products Ignition Intake Stroke FUEL Fuel/Air Mixture

4 Animasi Motor 4 Tak 4

5 5 Diagram PV (Pressure-Volume Graph) 4-stroke SI engine One power stroke for every two crank shaft revolutions 1 atm Spark TC Cylinder volume BC Pressure Exhaust valve opens Intake valve closes Exhaust valve closes Intake valve opens

6 6 IVO - intake valve opens, IVC – intake valve closes EVO – exhaust valve opens, EVC – exhaust valve opens X b – burned gas mole fraction Motored Four-Stroke Engine 10 Pressure (bar) 100 Intake Exhaust TC BC

7 7 IVO - intake valve opens, IVC – intake valve closes EVO – exhaust valve opens, EVC – exhaust valve opens X b – burned gas mole fraction Four-Stroke SI Engine Valve overlap Exhaust gas residual 10 Pressure (bar) 100 Intake Exhaust OVERLAPPING

8 8 Siklus Kerja Motor Bensin 2 Tak (Modern Two-Stroke Spark Ignition Engine) Stroke 1:Fuel-air mixture is introduced into the cylinder and is then compressed, combustion initiated at the end of the stroke Stroke 2:Combustion products expand doing work and then exhausted * Power delivered to the crankshaft on every revolution

9 9 Two Stroke Spark Ignition Engine Intake (“Scavenging”) Compression Ignition Exhaust Expansion Fuel-air-oil mixture Fuel-air-oil mixture Crank shaft Reed valve Exhaust Port* Transfer Port* *No valves and thus no camshaft

10 Animasi Motor 2 Tak 10

11 11 EPO – exhaust port open EPC – exhaust port closed IPO – intake port open IPC – intake port closed Two-Stroke CI Engine scavenging AiAi AeAe Intake area (A i ) Exhaust area (A e ) PiPi PePe Exhaust Press (P e ) Intake Press (P i ) Cylinder Press (P) 110 CA

12 12 Cross Loop Uniflow Pembilasan pada Motor 2 Tak (Scavenging in Two-Stroke Engine)

13 13 Kelebihan Motor 2 Tak: Power to weight ratio (PWR) lebih besar dibandingkan motor 4 tak karena menghasilkan tenaga setiap putaran poros engkol. Konstruksi sederhana, hanya ada saluran (ports) - tidak perlu mekanisme katup yang rumit Perawatan lebih mudah Banyak diaplikasikan pada motor kecil : sepeda motor, motor tempel, kompressor, pemotong rumput, gergaji mesin (chain saw), Kekurangan Motor 2 Tak: Pembilasan kurang sempurna (tidak selesai/terlalu bersih)  Emisi tinggi, bahan bakar tidak ekonomis Proses pembakaran tidak bersih karena membakar oli  Emisi tinggi

14 14 Single Cylinder Engine Motor 2 Tak menghasilkan Power (Langkah Usaha) setiap 1 putaran poros engkol (360 CA). Motor 4 Tak menghasilkan Power (Langkah Usaha) setiap 2 putaran poros engkol (720 CA). Interval torsi yang dihasilkan motor cukup jauh, menyebabkan getaran pada mesin. Dimensi mesin sangat kompak sehingga motor 1 silinder umumnya diaplikasikan pada kendaraan kecil. 180 CA (BDC) 0 CA (TDC) 720 CA (TDC) 540 CA (BDC) 360 CA (TDC) 4-stroke 2-stroke

15 15 Multi-cylinder Engines Multi-cylinder engines digunakan untuk mendistribusikan volume silinder motor pada beberapa silinder. Keuntungannya memperpendek interval torsi yang dihasilkan motor, sehingga mengurangi getaran dan menghasilkan karakter torsi yang dihasilkan lebih rata/halus. Konfigurasi yang umum digunakan: a. Inlineb. Vc. Boxer

16 DIAGRAM PROSES KERJA Menghitung: Panjang Proses (=Langkah):Jumlah Derajat Putaran 1 Siklus Jml Proses (=Langkah) Jarak Proses (=Langkah): Jumlah Derajat Putaran 1 Siklus Jml Silinder Motor Contoh: Motor 4 Tak 4 Silinder FO (Firing Order): Gambarlah: Diagram Engkol Diagram Proses Kerja 16

17 DIAGRAM PROSES KERJA Panjang Proses (=Langkah) = 2 x 360 CA 4 = 720 CA 4 = 180 CA Jarak Proses (=Langkah) = 2 x 360 CA 4 = 720 CA 4 = 180 CA 17

18 DIAGRAM PROSES KERJA FO: Diagram Engkol: 18 Cyl: 1, 4 CA: 0, 720 (TDC) Cyl: 2, 3 CA: 180, 540 (BDC)

19 DIAGRAM PROSES KERJA 19 CYL/CA INTAKECOMPRESSIONPOWEREXHAUST 2COMPRESSIONPOWEREXHAUSTINTAKE 3EXHAUSTINTAKECOMPRESSIONPOWER 4 EXHAUSTINTAKECOMPRESSION

20 TUGAS Gambarlah Diagram Engkol & Diagram Proses Kerja Motor 4 Tak 6 Silinder, FO: Motor 4 Tak 6 Silinder, FO: Lengkap dengan perhitungannya! Kumpulkan pada TM y.a.d! 20

21 Minggu depan belajar durasi katup & panjang langkah efektif See U Next Week, Wassalaam... 21


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