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4-stroke cycles compressed to single crankshaft revolution (Atkinson cycle)

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Presentation on theme: "4-stroke cycles compressed to single crankshaft revolution (Atkinson cycle)"— Presentation transcript:


2 4-stroke cycles compressed to single crankshaft revolution (Atkinson cycle)
Fully valve controlled gas exchange Diesel or Otto engine Turbo charger and supercharger (piston compressor) 2-cylinder Z engine provides equal power output to a 4-cylinder 4-stroke engine HCCI combustion Internal EGR Easily balanced mass forces Good torque characteristics Ignition controlled by multiple variables High downsizing degree Excellent transient behaviour Driving fun

3 What is Z engine? 4/2-stroke, 2-cylinder engine
Revolutionary working principle combines the best aspects of 2- and 4-stroke engines Part of the compression cycle is made outside of the working cylinder, so all of the cycles of 4-stroke engine can be done in a single crankshaft revolution Compact size Light weight Small emissions Low manufacturing costs

4 Exhaust cycle Exhaust valves opens 60° BBCD and closes 120° ABCD
 2 x 180° = 360° pulses for the turbo charger Exhaust gases hot enough for 3-way catalyst

5 Injection Fuel injected during 110° - 120° ABDC, when the exhaust valves are closing Long mixing time before the ignition, 60° – 70° Injection pressure 200 – 700 bar, duration 5° – 12° Hollow cone spray Small spray penetration Small droplets Fuel injected to hot exhaust gas  Partial fuel reforming High temperature and low pressure during injection  Rapid fuel evaporation Gas temperature an pressure during the start of the injection: 700 – 800 K, 1,5 – 2,5 bar Temperature drop of the gas in the cylinder during injection: 200 – 400 K Heat for fuel evaporation from exhaust gas

6 The temperature and pressure curves between 80° - 40° BTDC

7 Intake cycle (scavenging)
Intake valves opens 60° BTDC and closes 45° BTDC Intake pressure 4 – 15 bar  Velocity of intake gas: 300 – 500 m/s Intern EGR 15 – 45%, acts as an intern heat exchanger Hot, active radicals in EGR can be used to assist ignition No overlapping of intake and exhaust valves  No losses of intake gas Fuel evaporation cools the mixture: more air to the cylinder Electric heater in the intake channel for start

8 The theorethical valve flow

9 Final Compression Mechanical compression ratio: 14 – 15:1
Primary compression is made in piston compressor, secondary in work cylinder: 3-5:1 Short compression time  Low amount of heat transfer Fuel evaporation before final compression and high intercooling rate  Low compression temperature, more air in to the cylinder Compression temperatures at TDC: 800 K at part load, 700 K at full load  The compression temperature descend when load increases Lower gas temperature  Lower compression pressure, higher bmep

10 Ignition delay curve of HCCI mixture

11 PV diagram of the Z engine

12 Combustion and work cycle
SAHCCI (Spark Assisted Homogenous Charge Combustio Ignition) Controlled By: Temperature at TDC, lambda, injection amount and timing, intercooling rate, valve timing Pressure and temperature at TDC controlled by adjusting intake air pressure and temperature Low temperature at TDC: no self ignition Start of combustion: 5-15° ATDC Short combustion duration: high efficiency Lambda : low Tmax, low NOx Active radicals assist the ignition Active radicals lower CO and HC No knock, as ignition at the right side of NTC area

13 Together = - 1400 € lower production costs per engine!
Manufacturing costs compared to 4-cylinder turbodiesel engine equipped with Common Rail + DeNOx-catalyst + particulate filter = 2800 € 2 working cylinders less = € Compressor needed = € Low injection pressure, 2 low cost nozzles = € No DeNOx catalyst = € No particulate filter = € Together = € lower production costs per engine!


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