155. The efficient burning of fuel in a diesel engine is dependent upon the ____. A.temperature of compression B.atomization of the fuel C.penetration of the fuel D. All of above
注柴油机燃油良好燃烧依靠压缩温度，燃油雾化和燃油的渗透力。D
156. The blower type crankcase ventilation system ____. A.removes combustible gases in the crankcase
B.prevents the formation of combustible gases in the crankcase C.cools lubricating oil
D.improves cold weather starting
注 曲柄箱排气系统是除掉曲柄箱的可燃气体。A
157. What causes diesel fuel to be ignited in the cylinder of an operating diesel engine?
A.Sparkplug B.Heat of compression. C.Carburetor. D.Glowplug. 注 压缩热导致工作过程中的柴油机燃油点燃。B
158. What is commonly used to create turbulence in a diesel engine combustion system?
A.Shape of the piston crowns. B.Increasing the compression ratios. C.Increasing the piston crowns. D.Increasing the turbocharger gear ratio. 注 在柴油机燃烧系统里，通常用活塞头的形状来产生涡流。A
159. The purpose of compressing the air within the cylinder of a diesel engine is to ____.
A.produce the heat for ignition B.decrease injection lag
C.increase ignition delay D.aid in exhausting burnt gases 注 柴油机气缸空气进行压缩的目的是为了产生点燃所需的热量。A
160. The primary purpose of oil control rings on a diesel piston is to ____. A.provide a reservoir for cylinder lubrication
B.pump oil into the combustion space for cylinder cooling C.prevent excessive lubricating oil consumption D.allow hydraulic oil film formation on the cylinder 注 油环的主要作用是防止滑油消耗量过大。C
161. Turbulence is created in the cylinders of a diesel engine to ____. A.obtain injection lag B.help mix fuel and air
C.increase combustion pressure D.utilize higher injection pressures 注 柴油机气缸里的涡动有助于燃油和空气的混合。B
162. The main operating characteristic of diesel engines which distinguishes them from other internal combustion engines is the ____.
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A.method of supplying air B.cooling system
C.method of igniting fuel D.valve operating mechanism 注 柴油机区别于其他内燃机最主要的特征是燃油点火靠压燃。C
163. How are the pressure and temperature affected in a diesel engine cylinder during compression?
A.Pressure and temperature decrease. B.Pressure and temperature increase.
C.Pressure decreases and temperature increases. D.Pressure increases and temperature decreases. 注 在柴油机压缩过程中，压力和温度都升高。B
164. If the compression ratio is increased on any diesel engine ____.
A.the expansion ratio will decrease B.combustion will be slowed down C.thermal efficiency will decrease D.thermal effciency will increase
注 如果柴油机的压缩比增加，热效率将提高。D
165. Which of the factors listed has the greatest effect on the mechanical efficiency of a diese engine?
A.Temperature of the intake air. B.Friction within the engine.
C.Mechanicalcondition of the supercharger. D.Mechanical condition of the turbocharger, 注 柴油机的摩擦对其机械效率影响最大。B
166. The function of the piston compression rings used in a diesel engine is to ____. A.seal the space between the piston and liner
B.transmit heat from the piston to the cylinder liner C.reduce the amount of combustion gas blow-by D.All of the above.
注 柴油机压缩环的作用是密封、传热、减少窜气。D
167. The main function of piston compression rings is to ____. A.prevent excessive cylinderliner wear B.reduce friction losses in the engine
C.seal the space between the piston and the liner
D.limit upward flow of lube oil into the combustion space 注 压缩环的主要作用是密封活塞和缸套。C
168. The flywheel reduces speed fluctuations by ____.
A.maintaining a constant rack setting B.storing kinetic energy
C.maintaining equal exhaust pressure D.maintaining even camshaftspeed
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注 飞轮是通过储存动能来降低转速波动。B
169. Modern marine diesel engines equipped with mechanical fuel injection operate on a combustion phase(燃烧阶段) within the cycle which is ____.
A.entirely constant pressure B.entirely constant temperature
C.a combination of constant volume and constant pressure D.a combination of constant temperature and constant pressure
注 装有机械喷射的现代船用柴油机燃烧过程是走容和定压的混合过程。C
170. In a single acting, two-stroke/cycle, diesel generator engine, the power impulse in an individual cylinder occurs ____.
A.once every crankshaft revolution B.once every two crankshaft revolutions C.once every piston stroke D.twice every piston stoke
注 就单作用、二冲程发电柴油机来说，曲轴每转一圈，功率都会有脉动。A
171. Piston compression rings used in a diesel engine function to ____. A.transfer heat from the cylinder to the piston B.scrape oil from the sides of the piston
C.seal the combustion space from the crankcases D.prevent any piston contact with the cylinder liner
注 柴油机活塞压缩环的作用是密封燃烧室和曲轴箱。C
172. The highest loads applied to the diesel engine crankshaft main bearings are____ A.axial loads B.firing loads C.inertia loads D.centripetal loads 注 作用在柴油机曲轴主轴承上最大的负荷是燃烧负荷（气体力）。B
173. Combustion gases formed in the cylinder of a diesel engine are prevented from blowing past the piston by ____.
A. cylinder valves B.compression rings C.piston skirts D. oil rings 注 防止柴油机燃烧室燃气发生窜气的是压缩环。B
174. The purpose of the flywheel is to ____.
A.provide energy to operate the engine between power impulses B.neutralize the primary inertia force of the crankshaft C.reduce the shock of starting loads on the main bearings D.prevent the engine from operating at critical speed
注 飞轮的目的是在两次脉动之间提供能量（降低脉动率）。A
175. In a modern internal combustion diesel engine, the load carrying part of the engine is referred to as the ____.
A.bedplate or base B.sump or oil pan C.cylinder block D.frame 注 现代内燃机，机座承受部分柴油机的负荷。A
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176. In an internal combustion engine, which of the devices listed will force the compression rings to seal the compression gases in the space above the piston? A.Used of bimetallic piston rings. B.Ring gap pre-tensioning.
C.Thermalincreasein ring-end clearance
D.Gas pressure acting against the back of the ring
注 在内燃机里，燃气的密封是靠作用在活塞环背面的气体力来实现的。D
177. Valve lash, or clearance refers to the ____.
A.clearance between the top of the valve stem and the rocker arm B.compression of the valve springs
C.clearance between the valve seat inserts and the head D.out of roundness of the fuel injection cams
注 气阀间隙是指阀杆顶部和摇臂之间的间隙。A
178. In some modern large diesel engines, which of the following is used as the support for the main bearings?
A. Bedplate. B.Block. C.Base. D. Sump. 注 现代大型柴油机是用底座未支撑主轴承的。A
179. Piston cooling fins are located ____. A.atop the piston crown B.beneath the piston crown C.at the base of the piston skirt
D.inside the cylinder liner cooling water jacket 注 活塞冷却翅片位于活塞头的下面。B
180. Diesel engine valve springs function to ____.
A.hold the valves open
B.keep the valves off their seats untill the exhaust stroke is completed C.close the valves
D.open inlet valves when the air injection cycle begins
注 柴油机气阀弹簧的作用是关阀。C
181. Valve cages are used on some large diesel engines to ____. A.reduce wear on the valve stem
B.permit the use of alloy valve seat materials C.reduce heat transfer from the valve seat D.facilitate valve removal for servicing
注 一些大型柴油机采用带阀壳的气阀，其目的是方便拆阀维修。D
182. In a diesel engine, an integral liner is one in which the cooling water____
(Ⅰ) flows through the cylinder liner jackets,(Ⅱ) touches the outer side of the
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liner
A.(Ⅰ) only. B.(Ⅱ)only. C.Both (Ⅰ) and (Ⅱ). D.Neither (Ⅰ) and (Ⅱ) 注 柴油机气缸冷却水在水套里流动。A
183. Forcing the exhaust gases from the cylinder of an operating diesel engine with the aid of a blower is known as ____.
A.scavenging B.forced draft C.turbo-charging D.aspiration 注 柴油机在工作中借助鼓风机将废气从气缸中排除的过程叫扫气。A
184. In a trunk type diesel engine piston, the thickness of the head or crown is determined by the ____.
(Ⅰ) statically balanced; (Ⅱ) heat dissipation requirement。
A.(Ⅰ) only. B.(Ⅱ) only. C.Both (Ⅰ) and (Ⅱ). D.Neither (Ⅰ) nor (Ⅱ)
注 在筒形柴油机活塞中，活塞头的厚度由静平衡和散热要求决定。C
185. A crankshaft whose center of gravity coincides with its center line is said to be ____.
(Ⅰ) statically balanced;(Ⅱ)dynamically balanced.
A.(Ⅰ) only. B.(Ⅱ) only. C.Both (Ⅰ) and (Ⅱ). D.Neither (Ⅰ) nor(Ⅱ).
注 曲轴的重心和中心线重合即达到静平衡。A
186. At bottom dead center, the centerline of the connecting rod usually coincides with the ____.
A.angularity of the piston motion B.inertia moment from the piston C.centerline of the cylinder D.centerline of the king pin 注 在下止点连杆的中心线经常和气缸的中心线重合。C
187. The process of supplying a diesel engine cylinder with air at a pressure greater than atmospheric is called ____.
A.engine displacement B.super-aspirating C.air injection D.supercharging
注 向柴油机气缸里以高于大气压的压力供气的过程叫增压。D
188. In which of the scavenging methods listed will the exhaust valve be located in the cylinder head?
A. Return-flow. B. Uniflow. C. Cross-flow. D. Direct flow. 注 在直流扫气中，排气阀安装在气☆
189. The cylinder liner forming the cylinder wall and the inside of the water jacket is called a ____.
A. dry liner B. wet liner C. jacket liner D. corrugated liner 注 气缸套的外表面与冷却水直接接触叫湿式缸套。B
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