During the valve overlap period, the exhaust pressure of a turbocharged 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.

题目

During the valve overlap period, the exhaust pressure of a turbocharged four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure ______.

A.effective cylinder scavenging and cooling

B.constant pressure from the turbochargers

C.cooler operation of the exhaust system

D.effective constant pressure for turbocharger operation

相似考题

1.Any increase in the exhaust back pressure of a four-stroke/cycle diesel enginewill( ).A.reduce engine horsepower outputB.aid in silencing the exhaust noiseC.increase the mean effective pressureD.contribute to effective cylinder scavenging

2.单选题Valve overlap is the period during which （）.A the inlet valve is openB the exhaust valve is openC both valves are closedD both valves are open

3.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) MEP is lower and the scavenging air is cooling the exhaust gases (2) valve overlap in a four-strokeA (1) only is correctB (2) only is correctC both (1) and (2) are correctD Neither (1) or (2) are correct

4.单选题The period of valve overlap is when （）.A the inlet valve is openB the exhaust valve is openC both valves are closeD both valves are open

更多“During the valve overlap period, the exhaust pressure of a turbocharged four－stroke／cycle ”相关问题

  • 第1题：

    单选题
    The size of the exhaust valve opening is （）
    A

    most critical in a four-stroke cycle diesel engine

    B

    most critical in a two-stroke/cycle diesel engine

    C

    most critical in a four-stroke/cycle diesel engine if it is turbocharged

    D

    of equal importance in a two-stroke/cycle diesel engine as in a four-stroke/cycle diesel engine


    正确答案： A
    解析： 暂无解析

  • 第2题：

    单选题
    The exhaust system for a turbocharged two-stroke/cycle diesel engine functions to（）
    A

    discharge exhaust gases and smoke

    B

    furnish energy to the turbocharger

    C

    reduce engine room noise

    D

    all of the above


    正确答案： C
    解析： 暂无解析

  • 第3题：

    单选题
    In a closed cooling system for a turbocharged, four-stroke/cycle diesel engine, fluctuating water pressure can be caused by （）
    A

    improper venting of the cooling system

    B

    carrying the expansion tank water level too high

    C

    a totally clogged impeller in the cooling water pump

    D

    an incorrectly set cooling system temperature control


    正确答案： C
    解析： 暂无解析

  • 第4题：

    单选题
    Proper lubrication of the main bearing is more easily obtained in a single acting four-stroke/cycle diesel engine than in a single acting two-stroke/cycle diesel engine because （）
    A

    bearing pressure in a four-stroke/cycle acting single diesel engine is continually reversed

    B

    bearing pressure in a two-stroke/cycle single acting diesel engine is continually reversed

    C

    the maximum bearing pressure is higher in a single acting two-stroke/cycle diesel engine

    D

    two-stoke/cycle diesel engines require more complicated lubrication piping


    正确答案： B
    解析： 暂无解析

  • 第5题：

    单选题
    A turbocharged diesel engine will have an intake manifold pressure（）
    A

    constantly decreasing as engine load increase

    B

    constantly increasing as the amount of supercharging increases

    C

    approximately equal to exhaust manifold pressure at all times

    D

    approximately equal to atmospheric pressure at all times


    正确答案： A
    解析： 暂无解析

  • 第6题：

    单选题
    Clearance volume scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished （）.
    A

    during the valve overlap period

    B

    with only the exhaust valve open

    C

    at a pressure below atmospheric

    D

    without cooling the cylinders or pistons


    正确答案： C
    解析： 暂无解析

  • 第7题：

    单选题
    Any increase in the exhaust back pressure of a four-stroke/cycle diesel engine will （）.
    A

    reduce engine horsepower output

    B

    aid in silencing the exhaust noise

    C

    increase the mean effective pressure

    D

    contribute to effective cylinder scavenging


    正确答案： C
    解析： 暂无解析

  • 第8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 gases

    B

    energy supplied to the turbocharger

    C

    air pressure to the intake manifold

    D

    purge of exhausted gases from the cylinders


    正确答案： C
    解析： 暂无解析

  • 第9题：

    单选题
    Scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished（）
    A

    during the valve overlap period

    B

    with only the exhaust valve open

    C

    at a pressure below atmospheric

    D

    without cooling the cylinders or pistons


    正确答案： A
    解析： 暂无解析

  • 第10题：

    单选题
    Which of the listed components is considered to separate the high pressure side of a refrigeration cycle from the low pressure side of the cycle?（）
    A

    The condenser and the expansion valve

    B

    The king valve and the solenoid valve

    C

    The compressor and the expansion valve

    D

    The condenser and the solenoid valve


    正确答案： B
    解析： 暂无解析

  • 第11题：

    单选题
    If the engine is naturally aspirated, or is a small high-speed type with a centrifugal turbocharger, the period of valve overlap（）,ie when both valves are（）, will be and the exhaust valve will close some 10°top dead canter（）.
    A

    open；short；after

    B

    closed；short；after

    C

    open；long；before

    D

    closed；long；before


    正确答案： C
    解析： 暂无解析

  • 第12题：

    单选题
    A piston in a four-stroke/cycle diesel engine makes four strokes during each （）.
    A

    crankshaft revolution

    B

    mechanical cycle of operation

    C

    period of two combustion cycles

    D

    cycle of two events


    正确答案： B
    解析： 暂无解析

  • 第13题：

    单选题
    During the fuel injection period, fuel pressure must exceed cylinder gas pressure to （）.
    A

    ensure penetration and distribution of the fuel in the combustion chamber

    B

    ensure the needle valve is flushed clean during each injection

    C

    prevent combustion gas blowback into the open needle valve

    D

    prevent reflected pressure waves when the needle valve closes


    正确答案： D
    解析： 暂无解析

  • 第14题：

    单选题
    High exhaust temperatures from all of cylinder of a turbocharged, four-stroke/cycle diesel engine can be caused by an（）
    A

    inoperative turbocharger

    B

    inadequate fuel supply

    C

    overload on one cylinder

    D

    unequal load distribution


    正确答案： D
    解析： 暂无解析

  • 第15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 cooling

    B

    constant pressure from the turbochargers

    C

    cooler operation of the exhaust system

    D

    effective constant pressure for turbocharger operation


    正确答案： A
    解析： 暂无解析

  • 第16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 stroke

    B

    last part of the intake stroke only

    C

    early part of the injection stroke only

    D

    early part of the power stroke


    正确答案： A
    解析： 暂无解析

  • 第17题：

    单选题
    Exhaust valve openings in a diesel engine cylinder head are made as large as practical to （）
    A

    increase back pressure during the exhaust process

    B

    facilitate periodic replacement of the valves

    C

    reduce the pumping loss associated with scavenging

    D

    reduce tension on valve springs


    正确答案： A
    解析： 暂无解析

  • 第18题：

    单选题
    In an engine with air inlet valve and exhaust valve on its cylinder heads the fresh air will enter into the cylinder （） and the gases exhaust （）, there being an adequate overlap between the inlet opening and the exhaust closing.
    A

    downwards；upwards

    B

    upwards；downwards

    C

    downwards；downwards

    D

    upwards；upwards


    正确答案： A
    解析： 暂无解析

  • 第19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 pressure

    B

    At full load the intake manifold pressure and exhaust manifold pressure are equal

    C

    At full load the intake manifold pressure is less than the exhaust manifold pressure

    D

    At full load the intake manifold pressure is greater than the exhaust manifold pressure


    正确答案： B
    解析： 暂无解析

  • 第20题：

    单选题
    Turbocharged four-stroke/cycle diesel engines utilize valve overlap for（）.
    A

    improving cylinder scavenging

    B

    preheating the combustion chamber

    C

    reducing air charge density

    D

    preventing valve wear


    正确答案： C
    解析： 暂无解析

  • 第21题：

    单选题
    A four-stroke cycle, turbocharged, 1000 horsepower diesel engine has been operating under loadThe load suddenly increases, causing excessive black exhaust smoke, and a rapid rise in the lube oil temperatureIn response to this condition, you should:（）
    A

    reduce load

    B

    check your exhaust

    C

    adjust cooling water temperature

    D

    increase lube oil flow


    正确答案： A
    解析： 暂无解析

  • 第22题：

    单选题
    A four-stroke/cycle, 1000horsepower diesel engine fails to start at normal cranking speed with normal fuel pressure and ambient temperatureThe reason for the failure could be（）
    A

    glazed liners or pistons

    B

    high lube oil pressure

    C

    excessive compression ratio

    D

    worn valve seats and valves


    正确答案： C
    解析： 暂无解析

  • 第23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 space

    B

    equalize cylinder and exhaust manifold pressures

    C

    alleviate the difference in valve size between the intake and exhaust

    D

    flush out condensate that collects after each compression stroke


    正确答案： B
    解析： 暂无解析

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