Module 1 - Introduction Flashcards
Internal combustion engine design is driven by 2 global issues
Cost of fuel and emission controls
T/F: Size of engine dictates power produced
T
Reason for increase in smaller engines over the years
Use of turbocharger: air going into engine can be compressed (more power for smaller size/displacement)
Most motor vehicle fuels (gas and diesel) are derived from ______ oil
Crude
Supply
Crude oil reserves lim to few countries in the world (Middle East, Canada, Russie, Venezuela, U.S.)
World oil reserves are estimated to be depleted in 50 years - 3 more than previous estimate. Why the change?
Able to access more supply in the US via fracking
T/F: Largest and cheapest extraction of oil reserves located in politically stable countries where conflicts seldom affect oil production
F: Happen in UNSTABLE countries where conflicts often affect oil prod
Why would demand for oil be increasing?
Emerging countries are getting richer, so more people can now afford cars
Oil mining in Canada
- Most of oil trapped in bitumen sand
- Must be extracted then separated
- Requires high initial capital cost
T/F: Emission controls add cost to the car
T
Where is TC in a cylinder
Highest point of stroke, slightly below ‘ceiling’ of cylinder
Where is BC in a cylinder
Lowest point of stroke
Clearance volume, V_c
Volume above TC and below ceiling of piston
Rings on piston
Pressure ring prevents hot gas from bypassing piston (seal)
Oil ring acts as squidgy for oil on the pin, prevents oil from burning cylinder
Biggest difference betw historical and current engines
Speed at which strokes occur
T/F: Crank shaft position is always referenced from 90º
F: always referenced from TC, when connecting rod is fully vertical (considered 0º)
T/F: It takes half a crank revolution to make a full stroke
T
One stroke equals…
The piston moving from BC to TC (or vice versa) ONCE
4-stroke spark ignition engine process
Stroke 1: F/A mix introduced to cylinder through intake
Stroke 2: F/A mix compressed (ignition happens before piston reaches TC)
Stroke 3: Combustion occurs, product gases expand doing work
Stroke 4: Product gases pushed out of cylinder through exhaust
T/F: 2 power strokes for every 2 crank shaft revolutions (in 4-stroke SI)
F: 1 power stroke/2 crank shaft revolutions (“power” = combustion)
Why does combustion push piston down?
Elevated pressure
T/F: The cylinder volume starts at 0 on stroke 1 in the 4-stroke SI process
F: Starts at TC (since we have a little clearance volume at the top)
Ignition too early vs. too late
Early: Counteracts piston and loses work
Late: Lose opportunity to push piston down
Ignition timing is ________
Critical
T/F: Valve timing is extremely important in 4-stroke engine
T
