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单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,1 Engine Cooling System,The purpose of the cooling system is to keep the engine at its most,efficient operting,temperature at all engine speeds and all,driving con-ditions,Section 4 Engine Cooling and Lubricating Systems,发动机冷却与润滑系统,（一）发动机冷却系统,冷却系统的作用是控制发动机的温度，使发动机在各种转速和各种行驶状态下都能有效地工作。,1 Engine Cooling SystemSect,A great deal of heat is produced in the engine by the burning of the air-fuel mixture,Some of this heat escapes from the engine through the,exhaust gases,to keep the engine from,over-heating,But enough remains in the engine to cause serious trouble,，,the cooling system takes care of this,ad-ditional heat,Another important job of the cooling system is to allow the engine to heat up as quickly as pos-sible,，,and then to keep the engine at a constant temperature,There are two types of cooling sys-tems found on cars,：,liquid-cooled,and,air-cooled,混合气的燃烧在发动机中产生大量的热，其中部分热量通过废气被排出以阻止发动机过热。但是，残留在发动机中的余热仍足以使发动机受到严重损坏，冷却系统就是专门用来消除余热的。冷却系统还有一个重要任务，就是让发动机迅速预热，然后就让发动机保持恒定的温度。,冷却系统有两种：液冷和风冷。,A great deal of heat is pr,The cooling system on liquid-cooled cars circulates a,fluid,through pipes,and,passageways,in the engine,As this liquid passes through the hot en-gine it absorbs heat,，,cooling the en-gine,After the fluid leaves the engine,，,it passes through a,heat exchanger,，,or,radiator,，,which transfers the heat from the fluid to the air blowing through the exchanger,Some older cars,，,and very few mo-dem cars,，,are air-cooled,Since most cars are liquid-cooled,，,we will focus on that system in this article,液冷系统的流体在发动机中的管路和通道中循环流动。当液体流过发热的发动机时，就吸收了大量热量。当液体流出发动机时，通过热交换器或散热器，将液体变为气体吹走。,有些老式汽车和少数现代汽车采用风冷系统。因为大部分的汽车采用液体冷却，所以我们主要讨论液冷系统。,The cooling system on liqu,The liquid cooling system consists of water pumps,，,water jackets,，,engine fan,，,radiator,，,coolant reservoir tank,，,radiator cap,，,thermostat,，,hoses and so on,，,as is shown in Fig.7-26,The cooling system is built into the engine,There are,hollow,spaces around each engine cylinder and,combustion chamber,These hollow spaces are called,water jackets,，,since they are filled with water,When the engine is running,，,the water takes heat from the engine,，,becoming hot in the process,A water pump pumps the hot water from the engine water jackets into the radiator,液体冷却系由水泵、水套、发动机风扇、散热器（水箱）、副水箱、压力式水箱盖、节温器、水管等组成，如图,7-26,所示。冷却系统就设置在发动机中。每个气缸体和燃烧室周围都留有空腔，这些空腔装满了水，称之为水套。在发动机运行过程中水被加热，并以水循环方式把热量从发动机中带走。水泵从发动机水套中把热水抽到散热器中，,The liquid cooling system,The radiator has two sets of pas-sages,One set carries water,The other set carries air,（,pulled through by car motion and the engine fan,）,As the hot water passes through,，,it gives up its heat to the air passing through,The cooled water then reen-ters the engine,，,where it can pick up more heat,In operation,，,water conti-nuously circulates between the engine and radiator,，,carrying heat from the engine to the radiator,By this means,，,excessive,engine temperatures are prevented,散热器有两条通道：一条是水道，另一条是气道（空气是通过汽车行驶和发动机的风扇抽入的）。当热水流过水道时，气道中流通的空气使热水冷却，冷却后的水又重新进入发动机，再把发动机中的热量传导出去。在这一过程中，水不断地在发动机与散热器之间循环，水携带着热量从发动机流到散热器再散发出去。通过这个方法可避免发动机温度过高。,The radiator has two sets of p,9,8,7,6,4,5,3,2,1,10,Fig.7-26,1Water Jacket,；水套,2Heater,；暖气水箱,3Heater Hose,；暖气水管,4Thermostat,；节温器,5Water Pump,；水泵,6Pressure Cap,；压力式水箱盖,7Coolant Reservoir Tank,；副水箱,8Radiator Core,；散热器芯,9Hoses,；水管,10Fan Belt；,风扇皮带,98764532110Fig.7-261Wate,The water pump is a simple cen-trifugal pump,The water pump,，,driven by a belt from the engine crankshaft,，,circulates,the cooling liquid between the radiator and engine water jackets,The cooling liquid is water,Antifreeze com-pounds,are added to the water during the winter,The water jacket are cast into the,cylinder blocks,and,heads,The engine fan is us-ually mounted on the,water pump shaft,and is driven by the same,belt,that drives the pump and the ge-nerator,，,see Fig.7-27,水泵就是个简单的离心泵。水泵由发动机曲轴上的皮带驱动，使冷却液在散热器与发动机水套之间循环流动。冷却液是水，冬季在水中须加入防冻剂。水套被铸入气缸体和气缸盖内部。发动机风扇通常安装在水泵轴上，由驱动水泵和发电机的同一条皮带驱动，参见图,7-27,。,The water pump is a simple,The purpose of the fan is to provide a powerful draft of air through the radiator,The radiator is a device for holding a,large volume,of water in close contact with a large volume of air so that heat will transfer from the water to the air,The radiator core is divided into two,separate,and,intri-cate compartments,；,water passes through one,，,and air passes through the other,风扇的作用是向散热器提供强大的空气流，与大量空气密切接触的散热器内可以容纳大量的水，这样热量可以通过水散发到空气中。散热器芯为分离和间隔交错的两部分。冷却水在其中一部分中流过，空气在另一部分中通过。,The purpose of the fan is to p,Fig.7-27,1,2,3,1Water Pump,；水泵,2Pulley,；皮带盘,3Cooling Fan；,冷却风扇,Fig.7-271231Water Pump；水,The radiator is the largest part of the cooling system,，,most of the heat from the engine is transferred from the,coolant,to the,surroun-ding air,，,as is shown in Fig.7-28,The reservoir tank is connected to the overflow hose,When the hot coolant expands in the radiator,，,the,reservoir tank,allows coolant to flow in,As the system cools,，,the coolant will be drawn back into the radiator,水箱是冷却系
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