单选题For an ordinary four-stroke diesel engine the exhaust valves close （）.A after TDCB before TDCC after BDCD before BDC

题目
单选题
For an ordinary four-stroke diesel engine the exhaust valves close （）.
A

after TDC

B

before TDC

C

after BDC

D

before BDC

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.Fuel is admitted to a diesel engine cylinder through the ______.A.injector nozzlesB.carburetorC.exhaust portsD.intake valves

3.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.cooler operation of the exhaust systemD.effective constant pressure for turbocharger operation

4.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

更多“For an ordinary four-stroke diesel engine the exhaust valves”相关问题

  • 第1题：

    单选题
    For an ordinary modem marine four-stroke engine the inlet valves close （）.
    A

    after TDC

    B

    before TDC

    C

    after BDC

    D

    before BDC


    正确答案： A
    解析： 暂无解析

  • 第2题：

    单选题
    Air scavenging of a diesel engine cylinder（）
    A

    blows out the exhaust gases

    B

    supplies oxygen for combustion

    C

    cools the valves and cylinder walls

    D

    all of the above


    正确答案： C
    解析： 暂无解析

  • 第3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 pressure
    A

    Ⅰonly

    B

    Ⅱonly

    C

    bothⅠand Ⅱ

    D

    neitherⅠnor Ⅱ


    正确答案： B
    解析： 暂无解析

  • 第4题：

    单选题
    The satisfactory operation of diesel engine exhaust valves usually depends on（）
    A

    the proper back pressure

    B

    the cooling water temperature

    C

    correct timing and proper seating

    D

    accurate metering and the exhaust temperature


    正确答案： C
    解析： 暂无解析

  • 第5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 temperature

    B

    Low firing pressure and high exhaust temperature

    C

    Low compression pressure and low exhaust temperature

    D

    Low firing pressure and low exhaust temperature


    正确答案： C
    解析： 暂无解析

  • 第6题：

    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


    正确答案： B
    解析： 暂无解析

  • 第7题：

    单选题
    For an ordinary four-stroke engine the inlet valves open （）
    A

    after TDC

    B

    before TDC

    C

    after BDC

    D

    before BDC


    正确答案： A
    解析： 暂无解析

  • 第8题：

    单选题
    Diesel engine valve springs function to （）
    A

    hold the valves open

    B

    keep the valves off their seats until the exhaust stroke is completed

    C

    close the valves

    D

    open inlet valves when the air injection cycle begins


    正确答案： C
    解析： 暂无解析

  • 第9题：

    单选题
    A two-stroke/cycle diesel engine requires less starting air than a four-stroke/cycle diesel engine, of equal displacement, because the two-stroke/cycle diesel engine（）
    A

    has little or no internal friction

    B

    has a lower effective compression ratio

    C

    operates with scavenge air under a positive pressure

    D

    operates without energy absorbing intake and exhaust strokes


    正确答案： D
    解析： 暂无解析

  • 第10题：

    单选题
    If a four-stroke/cycle diesel engine is started by injecting air into the cylinder, the pistons receiving the charge of starting air must be（）
    A

    on the power stroke

    B

    on the exhaust stroke

    C

    at the end of the power stroke

    D

    at the start of the intake stroke


    正确答案： D
    解析： 暂无解析

  • 第11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12题：

    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 longer
    A

    (1) only

    B

    (2) only

    C

    both (1) and (2)

    D

    neither (1) nor (2)


    正确答案： D
    解析： 暂无解析

  • 第13题：

    单选题
    For an ordinary four-stroke engine the exhaust valves open （）.
    A

    after TDC

    B

    before TDC

    C

    after BDC

    D

    before BDC


    正确答案： D
    解析： 暂无解析

  • 第14题：

    单选题
    In a four-stroke cycle diesel engine the intake valves open （）
    A

    before TDC and close after BDC

    B

    after TDC and close after BDC

    C

    before TDC and close before BDC

    D

    after TDC and close before BDC


    正确答案： A
    解析： 暂无解析

  • 第15题：

    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-stroke
    A

    (1) only is correct

    B

    (2) only is correct

    C

    both (1) and (2) are correct

    D

    Neither (1) or (2) are correct


    正确答案： C
    解析： 暂无解析

  • 第16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17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18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19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20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21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 falters

    B

    Piston blow-by

    C

    A defective after-cooler

    D

    Faulty exhaust valves


    正确答案： A
    解析： 暂无解析

  • 第22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23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 springs

    B

    compressed air pressure

    C

    hydraulic pressure

    D

    exhaust gas pressure


    正确答案： D
    解析： 暂无解析

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