Fuel Induction Ignition And Starting Systems Flashcards
1
Q
Out of these fuels (natural gas, gasoline, propane and diesel) which has the highest heat value?
A
Diesel
2
Q
What is a BTU and what does it stand for?
A
- BTU is the measure of heat content of fuel. The amount of heat required to heat 1lb of a liquid by 1F
- British Thermal Unit
3
Q
What is the metric version of BTU?
A
- The Calorie. Its is the amount of heat needed to heat 1g of a liquid by 1C
4
Q
Are high Octane fuels faster burning or slower? What does this mean for car parts
A
- Slower
- High octane is better for car parts. There is a softer piston push.
5
Q
Are higher temps of air and high compressions ratios beneficial with diesel engines?
A
- Yes
6
Q
Are higher temps of air and higher compression ratios beneficial to spark plugs?
A
- No, this can lead to pre-ignition, detonation or both.
7
Q
The _______ the octane number, the more the fuel can resist self-ignition.
A
Higher
8
Q
Which has lower compression ratios CI-type of SI-type?
A
- SI-type
9
Q
Is fuel premixed with air before compression and ignited in SI-type systems
A
Yes
10
Q
What type of ignition is this?
What is happening?
A
- Pre-ignition
- Two flames are caused in the combustion chamber. One from the spark plug another from a hot spot else where. The flame fronts cause a fast burn which leads to abnormal pressure rise causing piston knocking.
11
Q
What type of ignition is this?
A
- Detonation
12
Q
Explain what detonation is?
A
Process where after spark plug ignition the flame causes the opposite sides air fuel mixture to compress even more and ignite prematurely. With these two flames fronts colliding excessive pressure builds in the cylinder causing knocking.
13
Q
What must be done to gasoline fuel before it enters the engine cylinders?
What methods are used to do this?
A
- Must be metered, atomized and mixed with air.
- Carburetor and Electronic Fuel Injection
14
Q
What are the four basic parts of a Carburetor?
A
- Carburator
- Fuel Pump
- Fuel Tank
- Filter
15
Q
What is this? Label the picture.
A
- Simple Carburetor
16
Q
What is a Venturi?
A
A restriction in the air horn (air intake) that creates a low pressure area (vacuum) in the carburetor sucking and mixing gas.
17
Q
What is the Throttle?
A
A butterfly valve that is the speed control mechanism for the engine. Controls the amount of air and fuel that enters the cylinders.
18
Q
What is the “Choke”?
A
Is a valve before the venturi or throttle that blocks the air horn (air supply tube) to increase the amount of fuel that enters the cylinders.
19
Q
What is an Expansion Tank?
A
It is similar to an accumulator but for fuel lines on engines. It is a spare resivour of fuel incase there is a moment where no fuel is delivered down the line.
20
Q
Is propane odourless and colourless?
Is air heavier?
A
- Yes, the egg smell is added to it later.
- No, propane is 1 1/2 times heavier then air.
21
Q
At what temperature is propane a liquid? How much does it expand?
A
- At - 42 C or -44 F or below
- 270 times when changing from liquid to gas
22
Q
What is the mandated capacity percent for propane in propane storage tanks?
And why?
A
- 80%
- Because of the large expansion rate
23
Q
Why are CI systems high compression?
A
- Because disel fuel needs a high temperature to ignite (has a high BTU value). And the higher the compression the hotter air gets which then ignities the fuel.
24
Q
Why is there a high pressure fuel injection system in diesel engines?
A
Because air is injected into the cylinder first then compressed to cause heat. Then the fuel is injected in and without the high pressure it would not pentrate the air, mix and atomize inside the cylinder.
25
Where does diesel fuel mix with air in a CI engine?
In the combustion chamber. Which is different then a gasoline engine.
26
What can be done to help a cold CI engine start.
Give the fuel some starting aid (chemical additive). This gives the engine some additional heat upon compression.
27
What are the two Fuel Injection System types?
- Mechanical Injection/ Mechanical Control
- Mechanical Injection/ Electrical Control
28
Name some Mechanical Injection/Mechanical Control subsystem types:
- Distribution Fuel Injection
- Inline Fuel Injection
- Unit Fuel Injection
29
What type of injection system is this?
Name all the parts.
Inline Fuel Injection
30
What is a Distributor Fuel Injection System?
Where is it used?
A Mechanical Injection/ Mechanical Controlled Fuel injection System that uses one high pressure pumping plunger that distributes and pumps fuel to a distribution head which is then diverted to each of the injector nozzles at each cylinder.
- Many small automotive diesel engines.
31
What is a Inline Fuel Injection Pump System?
A self-contained unit that has its own cam and plunger for each cylinder. Each one of these plungers (pumps) has a high-pressure line that goes to the individual cylinder injector.
32
What is this? Name the parts.
- Inline Injection Pump System and Metering Rack
33
What is the port and helix metering method?
For Inline Injection Pumps. Each plunger pump is geared to a rack that is controlled by the governor. The position of the governor linkage adjusts the rack, which then rotates the plumgers in their bore. This changes the position of the plunger helix port for when fuel is delivered to the injector.
34
What type of Injection System is this?
Unit Fuel Injection
35
What is a Unit Fuel Injector similar to? What is the difference?
- Inline Injector System
- The injector pump is mounted in the head of the engine. The engine cam drives the pumping element through a pushrod mechanism. as with the inline method, the metering is done using a port and helix method with the rack that is attached to the governor by a set of linkages.
36
How do you depressurize a Fuel System for a engine? What happens if you cannot disconnect the pump?
- Isolate the pump and supply and run the engine until it stalls. Then crank the engine for 20 to 30 seconds to clear the remaining pressure.
- Bleed the fuel pressure off into a cloth wrapped around the pressure test port or at a flexible fuel line disconnect.
37
What is the “Induction System” responsable for in an engine?
- Cleans intake air
- Ensure sufficant quantity of air for combistion
- Brings air to correct temp
- Aids cooling of valves and other internal parts by use air.
38
What happens if air is too hot for Induction Systems? What about too cold?
- The power drops off
- Too cold, lead to a drop in compression temp which results in poor fuel ignition and thermal shock to the engine.
39
What are the most efficient temps for an engine induction system?
15C to 32C
40
What is the difference between Pre-cleaners and Dry Air Cleaners?
- Pre-Cleaners are before the main air filter and remove large material. Dry Air Filters are a type of main filter and remove 99% of small particles by using pleaded paper as a medium.
41
What is this? Name its parts.
- Oil Bath Cleaner
42
How does a Oil Bath Cleaner work? How efficient is it?
- Most common type the air goes through a pre cleaner, down the central tube then encounters a sharp turn where the air hits oil and leaves its dirty particles. The air then goes through a oil mesh which further removers particles.
- 95% to 98%
43
Name four types of air cleaners.
Pre-Cleaner
Dry Air Filter
Oil Bath Air Cleaner
Spiral Rotor Air Cleaner
44
How does a Spiral Rotor Cleaner work?
- Centrifugal force is used to fling particles out of the air and into the wall. This collects down the wall.
45
What is the most accurate means of measuring an air cleaner restriction?
Using Water Manometer
46
What is very critical for an Oil Bath Air Cleaner in winter?
- When changing the oil make sure it is the right viscosity.
47
What are the risks for an Oil Bath Air Cleaner that is too small or too large?
- Too small and the oil can be pulled into the engine.
- Too large and there will not be enough air velocity to function efficiently
48
What does a Artifically Aspired Engine mean? Give some examples.
- To use some mechanical means of pushing air into the cylinders.
- Turbo charger, blower, piston type scavenge pump.
49
What does “Supercharge/Boost Pressure” mean?
- When Artifually Aspirated Engines have air charged inside the cylinders and bring the pressure above atmosphereic pressure.
50
What does Supercharging/ Boost pressure do?
Increases the power output.
51
Which type of engines have to be Artificially Aspirated?
- Two-stoke engines have to be Artifically Aspirated whereas four-stroke engines may or may not be.
52
What are responsible for distributing clean air or air fuel mixture evenly to the cylinders?
Intake Manifolds
53
What is Natural Aspiration?
When the atmospheric pressure is what pushes the air into the cylinder.
54
Explain Piston-type Scavenging Pumps.
When the underside of a piston and a seal crankcase are used to push air into a cylinder.
55
What are Piston-type Scavenging Pumps commonly used on?
Small Two Stroke Engines
56
What are Blowers in an engine? What does it do? What is unique about them as opposed to Turbochargers?
- Air pumps that are mechanically driven by the engine through a timing belt or gear drive.
- Supplies boost at all speeds and responds immediately.
57
What are Turbochargers?
- Essentially small gas turbines that use exhaust gases to drive the turbine wheel that is connected to a compressor wheel on the opposite end of the shaft.
58
What are Turbochargers used with?
Non-positive displacement compressors with high rotational speeds (10,000 to 100,000 rpm)
59
What Artificial Aspirator is this demonstrating? What what kind of motor? Name all the parts
- Lobe Blower
- On a two stroke engine
60
What type of displacement unit are Lobed Blowers?
- Positive Displacement
61
What type of displacement unit is a Centrifugal Blower? What do they look like?
- Non-positive Displacement
- Turbochargers
62
What drives the Centrifugal Blower?
- The crankshaft
63
What are the advantages of supercharging and engine?
64
What are the disadvantages of Supercharging?
- It creates higher internal stresses on engine parts
- More heat is created (piston cooling must be introduced)
65
What is this?
Turbocharger
66
How does a Turbocharger work?
Radial Flow Centrifugal Compressors. Exhaust gases expelled from the combustion chamber are fed to the turbine wheel which turns it, the shaft and the compressor wheel on the opposing side. The compressor wheel draws air because of this and feeds it back to the intake system for combustion.
67
What is Turbo-lag?
Because Turbochargers are not directly driven by the engine, turbo responses to engine load are delayed.
68
What drives a Turbocharger?
Heat of the waste exhaust
69
What is Boost?
The term used for the pressure created by a turbocharger.
70
What is this? What is attacted to it? Name all the parts.
Turbocharger with a waste gate valve attached.
71
What is the most common method of boost control? What is the most accurate method?
Sensing the ouput pressure of the compressor to operate the Waste Gate Valve. It is also the most accurate.
72
What is this and what does it depict?
Turbocharger with a waste gate attached.
73
What is the last item tipickly to recieve oil in an engine when starting up.
The turbocharger
74
What should you do when first starting up a engine with a turbocharger? Why?
- Should not rotate the engine at high rpm until oil has sufficient pressure.
- Because turbochargers are the last to recieve oil.
75
After heavy acceleration what should you do for a turbocharger?
Idle the motor to let the internal turbocharger parts cool down.
76
What could happen to the turbocharger if the engine is immediately turn off after heavy acceleration?
- Bearings could seize due to high heat and lack of librication.
77
What is a Distributor when regarding a ignition system.
A device in the ignition system which distributes electrical power to each cylinder in the correct sequence for ignition.
78
What are Capacitors and what are they used for?
- Voltage storage device that can be charged and discharged almost instantaniously.
- Stablizes voltage spikes and store/deliver power to the primary circuit in moderen magnetos.
79
What is another name for a Capacitor?
Condenser
80
When do you use a choke? Why?
- When the engine is starting up and is cold.
- It increases the concentration of fuel which provides more energy to warm up the engine.
81
What is a diode?
A solid state device that allows current to flow in only one direction. Like an electronic check valve.
82
What is a Zener Diode?
A solid state voltage-regulating device that can be specified for a specific voltage or voltage rating.
83
What is a Transistor? What is similar to them?
- An electronic switch that is turned on by a small current to one of its connections.
- Rectifiers
84
What is a Bridge Rectifier?
A solid state device that changes ac current into to dc current. Comprised of one or more diodes depending on how many phases the charge coils have.
85
What are flux lines?
Lines within an electric field from north to south.
86
Wrapping a conductor around an iron core does what?
Creates a Electromagnet
87
What is the magnetic strength of an electromagnet directly proportinal to? What other factor determines the strength?
- The current and the number of turns of wires in the coil
- Core material
88
What does emf stand for and what is it responsible for?
-Electromotive Force.
- when a conductor cuts across the lines of flux of a magnetic field a voltage is induced in the conductor. The cause is emf.
89
What are the two distinct circuits in a ignition system?
- Low Voltage Primary Circuit and High Voltage Secondary Circuit
90
What is the range of the Primary Circuit for Voltages?
6 - 30 volts dc
91
What are the main components of a Primary Circuit?
- Power Source (charging system)
- Ignition Switch
- Low Voltage Wiring
- Ignition Coil Primary Windings
- Switching Device
92
What is the voltage range for a Secondary Circuit?
15000 - 60000 volts dc
93
What are the main components of a Secondary Circuit?
- Ignition Coil Secondary Windings
- Spark Plug Wires
- Spark Plugs
94
What is a Ignition Coil?
A step up transformer that converts low voltage, high current into high voltage , low current. Turns primary current 6V- 30V into secondary current 15000V-60000V. This high voltage is required for to creat a spark across the electrodes of the spark plug.
95
Answer.
B)
