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单选题
What is the purpose of the intake/exhaust valves in a diesel engine? （）
A
They regulate the combustion cycle
B
They supply cooling water
C
They synchronize the ignition spark
D
They supply and regulate the lubricant flow
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更多 “单选题What is the purpose of the intake/exhaust valves in a diesel engine? （）A They regulate the combustion cycleB They supply cooling waterC They synchronize the ignition sparkD They supply and regulate the lubricant flow” 相关考题
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What is the function of the after-coolers installed in the diesel engine air intake system?A.Decrease the air densityB.Increase the exhaust temperatureC.Decrease the lube oil temperatureD.Increase the air density
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Exhaust gases are generally removed from the cylinders of a two-stroke/cycle diesel engine byA.natural aspirationB.masked intake valvesC.air ceilsD.scavenging air
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The closing of the exhaust valves used on a modern, large, low-speed, main propulsion diesel engine may be directly provided by_______.A.large conical springsB.compressed air pressureC.hydraulic pressureD.exhaust gas pressure
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Fuel is admitted to a diesel engine cylinder through the ______.A.injector nozzlesB.carburetorC.exhaust portsD.intake valves
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单选题For an ordinary four-stroke diesel engine the exhaust valves close （）.A
after TDCB
before TDCC
after BDCD
before BDC
考题
单选题Exhaust gases are generally removed from the cylinders of a two-stroke/cycle diesel engine by（）A
natural aspirationB
masked intake valvesC
air cellsD
scavenging air
考题
单选题The function of the after-cooler installed between the turbocharger and intake manifold on some diesel engine, is to （）A
increase the density of the intake airB
decrease turbocharger power usageC
reduce exhaust gas temperatureD
compensate for turbocharger PRM fluctuations
考题
单选题Air scavenging of a diesel engine cylinder（）A
blows out the exhaust gasesB
supplies oxygen for combustionC
cools the valves and cylinder wallsD
all of the above
考题
单选题In a four-stroke cycle diesel engine the intake valves open （）A
before TDC and close after BDCB
after TDC and close after BDCC
before TDC and close before BDCD
after TDC and close before BDC
考题
单选题In a diesel engine, exhaust valves open before the intake ports are uncovered to （） Ⅰ.reduce pumping losses Ⅱ.reduce back pressureA
ⅠonlyB
ⅡonlyC
bothⅠand ⅡD
neitherⅠnor Ⅱ
考题
单选题Poor combustion in a diesel engine can be caused by （）.A
high compression pressureB
low intake air temperatureC
low exhaust pressureD
high scavenge air temperature
考题
单选题A diesel engine emits blue exhaust smoke as a result of（）A
cold intake airB
excessive compression pressureC
excessive cylinder lubricationD
a light load
考题
单选题The satisfactory operation of diesel engine exhaust valves usually depends on（）A
the proper back pressureB
the cooling water temperatureC
correct timing and proper seatingD
accurate metering and the exhaust temperature
考题
单选题The loss of the diesel engine cylinder air charge through leaky valves, piston rings, worn or scored liners, would be indicated by which of the following sets of conditions?（）A
Low compression pressure and high exhaust temperatureB
Low firing pressure and high exhaust temperatureC
Low compression pressure and low exhaust temperatureD
Low firing pressure and low exhaust temperature
考题
单选题During the valve overlap period, the exhaust pressure of a turbochargers, four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure （）A
effective cylinder scavenging and coolingB
constant pressure from the turbochargersC
cooler operation of the exhaust systemD
effective constant pressure for turbocharger operation
考题
单选题The intake valves in a diesel engine are reseated by （）.A
cam followersB
push rodsC
combustion gasesD
valve springs
考题
单选题Scavenging in a four-stroke/cycle diesel engine occurs during the （）.A
last part of the exhaust stroke, and the first part of the intake strokeB
last part of the intake stroke onlyC
early part of the injection stroke onlyD
early part of the power stroke
考题
单选题Operating a diesel engine under light loads and at low temperatures for an exhaust for an extended period can result in（）A
formation of carbon on the intake and exhaust portsB
high water jacket temperaturesC
overheated pistons and cylindersD
an increase in lube oil viscosity due to fuel dilution
考题
单选题Diesel engine valve springs function to （）A
hold the valves openB
keep the valves off their seats until the exhaust stroke is completedC
close the valvesD
open inlet valves when the air injection cycle begins
考题
单选题Which of the following conditions can cause above normal air temperature to develop in the intake manifold of a four-stroke/cycle turbo-charged diesel engine?（）A
Clogged air intake faltersB
Piston blow-byC
A defective after-coolerD
Faulty exhaust valves
考题
单选题Which of the following statements is correct regarding a turbocharged four-stroke/cycle diesel generator?（）A
At zero load the intake manifold pressure is greater than the exhaust manifold pressureB
At full load the intake manifold pressure and exhaust manifold pressure are equalC
At full load the intake manifold pressure is less than the exhaust manifold pressureD
At full load the intake manifold pressure is greater than the exhaust manifold pressure
考题
单选题The process of scavenging a two-stroke/cycle diesel engine serves to（）A
improve fuel flow volumeB
cool the exhaust valvesC
reduce the intake air charge densityD
increase the temperature of exhaust gases
考题
单选题In comparison to exhaust valves, intake valves of diesel engines may be fabricated from low alloy steels because （）.A
the beveled edges of the intake valves provide for serf-centering during seatingB
intake valves utilize stellite-coated valve seat inserts which reduce wearC
the volume of air passing through intake valves is less than the volume of air passing through exhaust valvesD
intake valves are less affected to the corrosive action of exhaust gases
考题
单选题An indication of a diesel engine air intake being partially clogged, is （）.A
low firing pressure and low exhaust temperaturesB
low firing pressure and normal exhaust temperaturesC
high firing pressure and low exhaust temperaturesD
high firing pressure and high exhaust temperatures
考题
单选题A turbocharged, four-stroke/cycle diesel engine has a larger valve overlap than a naturally aspirated four-stroke/cycle diesel engine, in order to in crease the （）.A
temperature of the exhaust gasesB
energy supplied to the turbochargerC
air pressure to the intake manifoldD
purge of exhausted gases from the cylinders
考题
单选题The closing of the exhaust valves used on a modern, large, low-speed, main propulsion diesel engine may be directly provided by （）.A
large conical springsB
compressed air pressureC
hydraulic pressureD
exhaust gas pressure
考题
单选题In a turbocharged four-stroke/cycle diesel engine, the exhaust valve remains open until after top dead center and the intake valve opens before top dead center to（）.A
produce a scavenging effect in the combustion spaceB
equalize cylinder and exhaust manifold pressuresC
alleviate the difference in valve size between the intake and exhaustD
flush out condensate that collects after each compression stroke
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