单选题Many diesel engine exhaust valves are being constructed with hollow stems filled with sodium in order to （）Aprovide added wear protection against today’s corrosive quality of fuelBincrease overall valve strength due to the high gas pressuresCassist in dissipating heat due to the extreme operating temperaturesDreduce the overall weight of the valve thus helping eliminate valve spring surge and hammering
单选题
Many diesel engine exhaust valves are being constructed with hollow stems filled with sodium in order to （）
A
provide added wear protection against today’s corrosive quality of fuel
B
increase overall valve strength due to the high gas pressures
C
assist in dissipating heat due to the extreme operating temperatures
D
reduce the overall weight of the valve thus helping eliminate valve spring surge and hammering
参考解析
解析：
暂无解析
相关考题：
A two stroke diesel engine exhaust temperature will be lower than a four stroke diesel engine of the same displacement because the _____. ① MEP is lower and the scavenging air is cooling the exhaust gases ② valve overlap in a four strokeA.①B.②C.① and ②D.Neither ① nor ② is correct
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
Fuel is admitted to a diesel engine cylinder through the ______.A.injector nozzlesB.carburetorC.exhaust portsD.intake valves
单选题For an ordinary four-stroke diesel engine the exhaust valves close （）.Aafter TDCBbefore TDCCafter BDCDbefore BDC
单选题Diesel oil may be used to cool （） of a diesel engine.AcylindersBexhaust valvesCpistonsDfuel valves
单选题Air scavenging of a diesel engine cylinder（）Ablows out the exhaust gasesBsupplies oxygen for combustionCcools the valves and cylinder wallsDall of the above
单选题In a diesel engine, exhaust valves open before the intake ports are uncovered to （） Ⅰ.reduce pumping losses Ⅱ.reduce back pressureAⅠonlyBⅡonlyCbothⅠand ⅡDneitherⅠnor Ⅱ
单选题Diesel engine mufflers or silencers reduce the engine exhaust noise by （）Apassing the exhaust through long head pipesBdiffusing exhaust vibrations through activated carbon bafflesCincreasing the exhaust gas velocityDreducing the exhaust gas velocity
单选题Clogged or partially obstructed exhaust ports on a diesel engine can cause（）Aover-speeding of the engineBfailure of the engine to shut downCno effect of engine mounting boltsDhigh exhaust temperatures
单选题Diesel engine exhaust noise can be reduced in an exhaust muffler by （）Achanging the direction of exhaust gas flowBincreasing the exhaust gas velocityCchanging the exhaust gas weightDincreasing the exhaust gas static pressure
单选题The satisfactory operation of diesel engine exhaust valves usually depends on（）Athe proper back pressureBthe cooling water temperatureCcorrect timing and proper seatingDaccurate metering and the exhaust temperature
单选题The exhaust system of a diesel engine is usually designed to remove exhaust gases and to （）Aprovide exhaust back pressureBprevent exhaust smoke emissionsCpower a reciprocating superchargerDmuffle exhaust gas noise
单选题The size of the exhaust valve opening is （）Amost critical in a four-stroke cycle diesel engineBmost critical in a two-stroke/cycle diesel engineCmost critical in a four-stroke/cycle diesel engine if it is turbochargedDof equal importance in a two-stroke/cycle diesel engine as in a four-stroke/cycle diesel engine
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?（）ALow compression pressure and high exhaust temperatureBLow firing pressure and high exhaust temperatureCLow compression pressure and low exhaust temperatureDLow firing pressure and low exhaust temperature
单选题What is the purpose of the intake/exhaust valves in a diesel engine? （）AThey regulate the combustion cycleBThey supply cooling waterCThey synchronize the ignition sparkDThey supply and regulate the lubricant flow
单选题The intake valves in a diesel engine are reseated by （）.Acam followersBpush rodsCcombustion gasesDvalve springs
单选题In a diesel engine exhaust system, the cooling of the exhaust gases below their dew point, will result in （）Aincreased engine back pressureBsulfuric acid corrosionCsurface pitting of the turbochargerDmoisture impingement on the turbocharger compressor blade
单选题Diesel engine valve springs function to （）Ahold the valves openBkeep the valves off their seats until the exhaust stroke is completedCclose the valvesDopen inlet valves when the air injection cycle begins
单选题The pressure in an operating diesel engine cylinder continues to rise for a short period after the piston passes top dead center as a result of the （）Aexpansion of the combustion gasesBexhaust and intake valves just closingCmaximum compression is just being attainedDfuel injection occurring at that point and combustion begins
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?（）AClogged air intake faltersBPiston blow-byCA defective after-coolerDFaulty exhaust valves
单选题Low compression pressure in a diesel engine may be the result of （）Ainsufficient fuel supply due to fuel pump valves sticking or leakingBexcessive mechanical clearance between the piston crown and cylinder headCexcessively worn fuel pump plungerDexcessive exhaust back pressure
单选题In comparison to exhaust valves, intake valves of diesel engines may be fabricated from low alloy steels because （）.Athe beveled edges of the intake valves provide for serf-centering during seatingBintake valves utilize stellite-coated valve seat inserts which reduce wearCthe volume of air passing through intake valves is less than the volume of air passing through exhaust valvesDintake valves are less affected to the corrosive action of exhaust gases
单选题An indication of a diesel engine air intake being partially clogged, is （）.Alow firing pressure and low exhaust temperaturesBlow firing pressure and normal exhaust temperaturesChigh firing pressure and low exhaust temperaturesDhigh firing pressure and high exhaust temperatures
单选题If you observe smoke coming from the turbocharger of an auxiliary diesel engine, you should（）Acheck the air filter for obstructionBcheck for an exhaust leakCcheck the exhaust temperatureDsecure the engine
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 （）.Alarge conical springsBcompressed air pressureChydraulic pressureDexhaust gas pressure
单选题“This increase in charge air density is accomplished on most modern diesel engine types by use of exhaust gas turbo-charging, in which a turbine wheel driven by exhaust from the engine is rigidly coupled to a centrifugal type air compressor” According to this sentence, we can know that increases density（）, drives the compressor directly（）Aa modern diesel engine；a turbine wheelBa modem diesel engine；exhaust gasesCa compressor；an exhaust gas turbochargerDa compressor；a turbine wheel
单选题A two-stroke diesel engine exhaust temperature will be lower than a four-stroke diesel engine of the same displacement because the （） (1) scavenging air is cooling the exhaust gases (2) exhaust cycle time is longerA(1) onlyB(2) onlyCboth (1) and (2)Dneither (1) nor (2)