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chapters 1+2 Flashcards

1
Q

What is an Internal Combustion Engine (ICE)?

A

Heat engine that converts chemical energy in a fuel into mechanical energy, usually made available on a rotating output shaft, through combustion that takes place inside the mechanical engine system.

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2
Q

What are reciprocating engines?

A

ICE having pistons that reciprocate back and forth in cylinders internally within the engine.

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3
Q

What were the two key technologies that enabled the development of ICE and the automobile in the late 1800s?

A
  • Discovery of crude oil in Pennsylvania in 1859
  • Pneumatic tires by Dunlap in 1888
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4
Q

Which ignition type starts combustion through a spark plug?

A

Spark Ignition (SI)

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5
Q

What is the main difference between Spark Ignition (SI) and Compression Ignition (CI)?

A

SI uses a spark plug for combustion, while CI relies on self-ignition due to high compression temperature.

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6
Q

What is the four-stroke cycle?

A

A cycle that experiences four piston movements over two engine revolutions.

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7
Q

What is a two-stroke cycle?

A

A cycle that has two piston movements over one revolution.

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8
Q

What is the function of a camshaft?

A

Rotating shaft used to push open valves at the proper time in the engine cycle.

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9
Q

What does TDC stand for in engine terminology?

A

Top-Dead-Center

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10
Q

In engine cycles, what does BDC stand for?

A

Bottom-Dead-Center

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11
Q

What is the purpose of a catalytic converter?

A

To reduce emissions by chemical reaction.

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12
Q

What is the difference between Direct Injection (DI) and Indirect Injection (IDI)?

A

DI injects fuel directly into the main combustion chamber, while IDI injects fuel into a secondary chamber.

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13
Q

What is the clearance volume in an engine?

A

Minimum volume in the combustion chamber with the piston at TDC.

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14
Q

What is a smart engine?

A

Engine with computer controls that regulate operating characteristics based on sensor inputs.

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15
Q

What does the acronym EMS stand for in engine management?

A

Engine Management System

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16
Q

What is the function of the fuel injector?

A

A pressurized nozzle that sprays fuel into the incoming air.

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17
Q

What is the role of the crankshaft in an engine?

A

Rotating shaft through which engine work output is supplied to external systems.

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18
Q

Fill in the blank: A _______ engine has pistons positioned in a circular plane around a central crankshaft.

A

Radial

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19
Q

What does the term ‘overhead valve’ refer to?

A

Valves mounted in engine head.

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20
Q

What is the purpose of the throttle in an SI engine?

A

To control the amount of air flow into the engine.

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21
Q

What is the function of the flywheel in an engine?

A

Stores energy and provides angular momentum to keep the engine rotating between power strokes.

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22
Q

What is the main purpose of the radiator in an engine?

A

To remove heat from the engine coolant.

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23
Q

True or False: A turbocharger is powered by the engine’s exhaust flow.

A

True

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24
Q

What type of fuel is commonly used in Spark Ignition engines?

A

Gasoline

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25
What does the term 'displacement volume' refer to?
Volume displaced by the piston as it travels through one stroke.
26
What is the advantage of using a supercharger?
Increases intake air pressure using power from the crankshaft.
27
Fill in the blank: The _______ is a mechanical linkage between the piston and the crankshaft.
Connecting rod
28
What is the first stroke of the four-stroke SI engine cycle called?
Intake or induction stroke ## Footnote The piston travels down from TDC to BDC with the intake valve open and exhaust valve closed, drawing air and fuel in.
29
What occurs during the compression stroke of a four-stroke SI engine?
The piston travels from BDC to TDC with all valves closed, compressing the air-fuel mixture ## Footnote Compression raises the pressure and temperature, and ignition occurs near the end of this stroke.
30
What type of combustion occurs during the four-stroke engine cycle?
Almost constant-volume combustion ## Footnote Combustion occurs quickly when the piston is near TDC, changing the gas composition to exhaust products.
31
What is the purpose of the expansion or power stroke in a four-stroke SI engine?
To produce work output by pushing the piston away from TDC ## Footnote High pressure from combustion causes the piston to move from TDC to BDC.
32
What is exhaust blowdown in a four-stroke engine cycle?
The process when the exhaust valve opens late in the power stroke ## Footnote High pressure and temperature push exhaust gas into the exhaust system, reducing thermal efficiency.
33
What happens during the exhaust stroke in a four-stroke SI engine?
The piston pushes remaining exhaust gases out of the cylinder ## Footnote The exhaust valve remains open, and the piston travels from BDC to TDC.
34
Define 'valve overlap' in the context of a four-stroke engine.
The period when both the intake valve and exhaust valve are open ## Footnote Occurs near TDC as the exhaust valve closes and the intake valve opens.
35
What is the first stroke in the two-stroke SI engine cycle?
Expansion or power stroke ## Footnote High pressure from combustion forces the piston down towards BDC.
36
What is scavenging in a two-stroke engine cycle?
The process of using incoming air-fuel mixture to push out remaining exhaust gases ## Footnote Occurs after blowdown when the intake port opens.
37
What distinguishes the compression stroke in a two-stroke engine from a four-stroke engine?
All valves (or ports) are closed during compression ## Footnote Piston compresses the air-fuel mixture to higher pressure and temperature.
38
What is a hybrid vehicle?
A vehicle that uses an electric motor and internal combustion engine ## Footnote It provides better fuel economy and lower emissions.
39
List some advantages of hybrid vehicles.
* Better fuel economy * Fewer emissions * Shut off IC engine when not needed * Regenerative braking energy recovery
40
What are some disadvantages of hybrid vehicles?
* Higher cost * Higher weight * Battery disposal environmental impact * More complicated management of systems
41
What is a fuel cell?
An efficient method for converting chemical energy into electricity with less emissions ## Footnote It can serve as an alternative electricity source to drive vehicle motors.
42
What are some challenges associated with fuel cell technology?
* Weight * Heat rejection * Freezing * Cost * Safety * Startup time * Refueling
43
What are the four main pollutants from automobile exhaust?
* Hydrocarbons (HC) * Carbon monoxide (CO) * Nitrogen oxides (NOx) * Solid particulates
44
What solutions have been implemented to reduce engine emissions?
* Improved engine and fuel technology * Exhaust aftertreatment systems (thermal or catalytic converters)
45
What does a bore to stroke ratio of less than 1 indicate?
Under square engine design ## Footnote These engines have a long stroke and small bore, leading to advantages like less heat loss.
46
What is indicated work (wi) in an internal combustion engine?
Work inside the combustion chamber during compression and power strokes ## Footnote It is part of the overall work output of the engine.
47
What is brake work (wb)?
wb = wnet - wf ## Footnote It represents crankshaft output after accounting for friction and parasitic loads.
48
What is the maximum brake mean effective pressure (bmep) for naturally aspirated SI engines?
120-150 psi ## Footnote This is a measure useful for comparing engine performance.
49
What is the typical range for maximum torque in automobiles?
200 to 300 N-m at 4000 to 6000 RPM ## Footnote Maximum brake torque speed (MBT) is when maximum torque occurs.
50
What is the definition of power (Wdot) in an engine context?
Power = rate of work ## Footnote Units are typically kW or HP.
51
What are the typical units for brake specific fuel consumption (bsfc)?
lbm/hp-hr or gm/kW-hr ## Footnote It indicates the fuel efficiency of an engine.
52
What are the four main engine exhaust emissions that must be controlled?
* Oxides of nitrogen (NOx) * Carbon monoxide (CO) * Hydrocarbons (Hc) * Solid particulates ## Footnote These emissions have significant environmental impacts.
53
What is volumetric efficiency?
The actual injected air per stroke vs. the benchmark of filling the displacement volume with atmospheric pressure air ## Footnote Typical values for WOT are 75% to 90%.
54
What is the function of a dynamometer?
Measures torque and power over the engine operating speed and load ## Footnote Different designs include mechanical friction, hydraulic, and eddy current types.
55
What is the typical combustion efficiency (ηc) in internal combustion engines?
Typically 95% to 98% ## Footnote It measures the fraction of fuel that burns during combustion.
56
What does the term 'specific fuel consumption' refer to?
The amount of fuel consumed per unit of power produced ## Footnote It is often calculated as brake specific fuel consumption (bsfc) or indicated specific fuel consumption (isfc).
57
What are the benefits of a 42-Volt electrical system in modern vehicles?
* More electric power available * 25% less electrical component mass * Better control with electromechanical valves * Improved performance and efficiency ## Footnote Transitioning from 12V to 42V is expected to enhance vehicle functionality.
58
What does variable displacement – cylinder cutout aim to achieve?
More efficient operation by reducing displacement volume under low power conditions ## Footnote It can lead to 5% to 15% fuel savings.
59
True or False: The maximum brake power in automobiles peaks around 6000 to 7000 RPMs.
True ## Footnote This is typically about 1.5 times the engine speed where maximum torque occurs.
60
What is the significance of the equivalence ratio in combustion?
It indicates the ratio of actual fuel-to-air ratio to the stoichiometric fuel-to-air ratio ## Footnote It affects combustion efficiency and emissions.

ice (6 decks)

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