Air Cooled Engine Technology. Roth 9 th Ch 5 2 & 4 Cycle Engines Pages PDF Free Download

Roth 9 th Ch 5 2 & 4 Cycle Engines Pages 81 94

1. The of the piston is its movement in the cylinder from one end of its travel to another. Either TDC to BDC (downstroke) or BDC to TDC (upstroke). Identified by the job it does. Bore Stroke Cycle

2. The stroke of an engine is a measurement of the the piston travels. This distance is expressed in either inches (American standard) or millimeters (metric ISO). Diameter Distance Radius

3. Name the 4 strokes in order:

4. strokes of the piston are needed to complete the 4 stroke cycle of operation. Overhead Valve Engine Shown

4. strokes of the piston are needed to complete the 4 stroke cycle of operation. L Head or Side Valve Engine Shown

5. strokes of the piston are needed to complete 2 stroke cycle operation.

6. A crankshaft turns degrees of rotation (1/2 turn) for every one stroke of the piston. 180º 360º 90º

7. Circle or highlight the correct responses for what happens in each of the strokes.

Piston Travels: TDC to BDC BDC to TDC Intake Valve: Open Closed Exhaust Valve: Open Closed Crankshaft Turns: 1/2 turn (180 ) 1/4 turn (90 ) Camshaft Turns: 1/2 turn (180 ) 1/4 turn (90 ) Air/Fuel Mixture: Enters the cylinder Leaves the cylinder

8. The crankshaft turns a total of degrees (2x) in one power cycle. (4 strokes x 180 each = 720 ) ½ Turn 180º ½ Turn 180º ½ Turn 180º ½ Turn 180º 180º 360º 720º

½ Turn 180º ½ Turn 180º ½ Turn 180º ½ Turn 180º

9. The camshaft turns a total of degrees (1x) in one power cycle. (4 strokes x 90 each = 360 ) 90º 360º 720º

10. pressure outside of the engine forces air through the carburetor as the piston creates a low pressure in the cylinder by moving downward on the intake stroke. Gravity Atmospheric Tidal

11. The air/fuel mixture is to raise its temperature, making it easier to ignite. Compression also guarantees a huge release of power as the burning fuel expands. Expanded Burned Compressed

12. The power stroke is started as the air/fuel mixture ignites due to electricity jumping the between the center and side electrodes of the spark plug. About 12,000 volts is required to jump.030 plug gap. Gap Tap Rap

13. is the proportionate difference or comparison of total cylinder volume with the piston at BDC vs. at TDC. (cylinder displacement combustion chamber volume = ratio) Compression Pressure Compression Distance Compression Ratio

14. Removal of the spent air/fuel mixture during the exhaust stroke is known as. The process of the incoming air actually pushing out the exhaust gases is carefully engineered. Scavenging Burning Compressing

15. The exhaust valve is cooled by conduction of heat from the valve face to the valve and from the valve stem to the valve. (a valve is only seated for about 1/50th of a second at 3600 RPM) Seat, Guide Face, Stem Lobe, Spring

16. The intake valve is cooled by the incoming / mixture passing over it. Air/Exhaust Air/Fuel Air/Debris

17. Valve is measured in degrees of crankshaft rotation. It effects horsepower, torque & emissions. Timing Under cut Over time

18. The term defines the time (in degrees) between the end of an exhaust event and the beginning of the next intake event when both valves are open. Valve Opening Valve Underlap Valve Overlap

Blue Line = Intake Valve Red Line = Exhaust Valve 12º + 180º + 40º = 232º Intake Duration 12º + 21º = 33º Valve Overlap 47º + 180º + 21º = 248º Exhaust Duration

19. Answer the following questions using the valve timing diagram. A) total number of degrees the intake valve is open: B) total number of degrees the intake valve is closed: C) total number of degrees the exhaust valve is open: D) total number of degrees the exhaust valve is closed: E) total number of degrees with no valves open: F) total amount of valve overlap in degrees:

20. The 2 most common methods of 4 stroke cycle engine lubrication are &. Splash Pump

21. The 2 stroke cycle engine has fewer moving parts & is lubricated by having a special either pre mixed with its fuel or injected with its fuel. This makes the lubrication system all position. Oil Gas Chemical

22. The scavenged 2 cycle uses the action of the contoured piston crown, directing the incoming A/F charge upward & across the inside of the cylinder to push out the exhaust gases. Loop Cross Poorly

23. The scavenged 2 stroke engine uses either a flat or a domed piston crown to swirl the incoming A/F charge around in the cylinder as it pushes out the exhaust gases. Loop Cross Poorly

24. One cycle of power is completed with only (1x) of crank rotation in a 2 stroke cycle engine. 180º 360º 720º

25. Some well engineered exhaust systems use the energy of waves to create a back pressure or tuning which prevents the incoming air/fuel charge from leaving with the exhaust gases. Tidal Sound Radio

26. Two stroke cycle engines use either valves, rotary valves, or can use the skirt as a valve to control the air/fuel mixture entering the crankcase. (3rd port valving = piston skirt use) Reed, Piston Seed, Mister Reed, Camshaft

27. A reed is a heavy steel strap used to prevent the reed valve from opening too far & becoming permanently distorted with excessive stand off. (Stand off over.010 open causes a no start condition) Chop Stop Plop

28. 2 cycle engines are in size, lighter in, have very quick, burn more fuel per hour and can be efficiently lubricated at any angle of operation. Smaller, Weight, Acceleration Larger, Weight, Acceleration Prettier, Weight, Deceleration

29. 4 cycle engines are in size, heavier in, have slower, burn less fuel per hour, are cooler running, and are limited to one position operation because of lube. Smaller, Weight, Acceleration Larger, Weight, Acceleration Prettier, Weight, Deceleration

30. Using illustration 5 10 on page 88 in your text, complete the statements about 2 cycle operation. ABOVE THE PISTON ON THE UPSTROKE The air/fuel/oil mixture is being. At about TDC, the occurs at the spark plug to begin combustion. ABOVE THE PISTON ON THE DOWNSTROKE The fuel charge burns and the piston downward. The exhaust is uncovered and the spent fuel charge is scavenged out as the piston opens the transfer port. Compressed Spark Forces Port

30. Using illustration 5 10 on page 88 in your text, complete the statements about 2 cycle operation. ABOVE THE PISTON ON THE UPSTROKE The air/fuel/oil mixture is being. At about TDC, the occurs at the spark plug to begin combustion. Compressed Spark ABOVE THE PISTON ON THE DOWNSTROKE The fuel charge burns and the piston downward. The exhaust is uncovered and the spent fuel charge is scavenged out as the piston opens the transfer port. Forces Port

30. Using illustration 5 10 on page 88 in your text, complete the statements about 2 cycle operation. BELOW THE PISTON ON THE UPSTROKE The fresh air/fuel/oil mixture that was in the carburetor enters the crankcase to lubricate all of the internal parts. BELOW THE PISTON ON THE DOWNSTROKE The fresh fuel charge in the crankcase is lightly pressurized & it awaits movement to the combustion chamber through the ports. Atomized Transfer

30. Using illustration 5 10 on page 88 in your text, complete the statements about 2 cycle operation. BELOW THE PISTON ON THE UPSTROKE The fresh air/fuel/oil mixture that was in the carburetor enters the crankcase to lubricate all of the internal parts. Atomized BELOW THE PISTON ON THE DOWNSTROKE The fresh fuel charge in the crankcase is lightly pressurized & it awaits movement to the combustion chamber through the ports. Transfer

The rotary engine (also called Wankel) uses a rotor and an eccentric shaft instead of the piston, connecting rod, and crankshaft used in a reciprocating piston engine. German Design

Dr. Felix Wankel http://www.prelovac.com/vladimir/wankel engine

The rotary engine, developed by a German scientist, operates off of the basic 4 stroke cycle ideas but uses no piston, cylinder, connecting rod, crankshaft or reciprocating motion. www.geocities.com/zenjoe/rotary.html Rotary Reciprocating Orbital

Air Cooled Engine Technology. Roth 9 th Ch 5 2 & 4 Cycle Engines Pages 81 94