Atkinson cycle

Atkinson cycle

Introduction Discovery of cycle Ideal thermodynamic cycle processOtto cycle vs. Atkinson cycleTypes of engines that use this cycleWho uses these engines?Cost analysis of Gas Engine

Discovery of cycleDiscovered by British engineer James Atkinson in 1882Patented on August 2, 1887 under Patent number: US 367496Was awarded the John Scott Medal of The Franklin Institute in 1889 for his invention

The true Atkinson cycle and the modern Atkinson cycle

A true Atkinson cycle used a complex linkage system in order for the power and exhaust stroke to be longer than the intake and compression stroke

The true Atkinson cycle and the modern Atkinson cycle

Atkinson cycle achieved through late valve closureThe modern Atkinson cycle uses a modified Otto cycle where the complex linkage is replaced by variable valve timing in which the intake valve is held open longer to let some of the air fuel mixture to leave the cylinder

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Ideal thermodynamic cycle processProcess 1-2: Isentropic compressionProcess 2-3: Constant volume heat additionProcess 3-4: Isentropic expansionProcess 4-1: Constant pressure heat rejection

Otto cycle vs. Atkinson cycle

Otto CycleV.S.Atkinson Cycle

Atkinson EnginePROSCONSRun relatively quietlySmooth idling speedsReliableRelatively low amounts of smokeHigher overall efficiencyComplicatedHeavy in weightCostly repairsLess power

How It All WorksUses less fuelMore efficientLess powerReduced charge Reduced powerClean burn

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Types of engines that use this cycleDifferential engineGas engineRotary Atkinson-cycle engineHybrid System Engine

Who uses these engines?

Figure 1. The 1.2-Liter Turbo Engine

The first car company uses the Atkinson cycle engine is Toyota. Toyota Motor Cooperation have developed their 14 high efficiency engines. One of them is Toyota Auris 1.2-liter turbocharged engine that uses lean burning Atkinson cycle technology.

Figure 2. Lexus IS 200T Engine

The Lexus IS 200T engine initially runs Otto cycle, and then it switches to the Atkinson cycle. This engine is able to deliver power of 180KW, and to accelerate to 62 miles per hour in a short period of time of 7 seconds

Differential engine

The Atkinson differential engine is designed to provide efficiency at the expense of the total power produced.It comprises of a single crankshaft that is connected non-linearly by a pin jointed link to two opposed pistons.

In each revolution, one piston provides a compression stroke and a power stroke, while the other piston provides an exhaust stroke and a charging stroke. the differential engine aims to use all of the energy in the cylinder by leaving the intake valve open longer, to create shorter compression strokes.

Gas engine

The Atkinson cycle aims to use all of the energy in the cylinder. It does this by leaving the intake valve open longer, creating a shorter compression stroke.

Gas engine cost analysisAtkinsonCostFull Hybrid System$3500Fuel cost per year$556.68Total$4056.68

OttoCostFull System$3500Fuel cost per year$1357.93Total$4857.93

Calculating Fuel Cost:

Questions?