Unit 3 Engine Cooling and Lubrication System,1. Engine Cooling System The cooling system is used to keep the engine at the most efficient operating temperature. The cooling system is composed of the water jacket (inside the cylinder block and cylinder head), radiator, water pump, thermostat, fan, hoses and other components. Fig 1-3-1 shows the parts of a cooling system.,efficient 效率高的 water jacket 水套 radiator 散热器，水箱 water pump 水泵 thermostat 节温器 hose 软管,Cooling System （冷却系统）,Fig. 1-3-1 1-radiator(散热器) 2-securing clip（固定夹）3-securing rubber （固定橡胶） 4 - upper coolant hose （上部冷却液软管） 5-rubber washer（橡胶垫） 6-radiator fan（冷 却风扇）7- fan ring（风扇罩壳）8- locking bolt（紧固螺栓）9-nut（螺 母）10-2 pin connector（双头插式插 头）11-lower coolant hose（下部冷却 液软管）12-O ring（O型圈）13- connector（连接插头）14-radiator fan thermo switch（散热风扇的热敏开 关）15- seal(密封圈) 16 drain screw（排水螺栓）,(1) Radiator and Fan The radiator performs the function of cooling the coolant which has passed through the water jacket and become hot, and it is mounted in the front of the vehicle. A fan is mounted behind the radiator to assist the flow of air through the radiator. The fan operates when the engine coolant temperature becomes high in order to prevent it from becoming too high. (2) Radiator Cap A relief valve ( pressurization valve ) and a vacuum valve ( negative pressure valve ) are built into the radiator cap. It is used to maintain the correct and constant pressure on the cooling system. (3) Water jacket The water jacket is the open spaces within the cylinder block and cylinder head through which coolant passes.,perform 执行 assist 帮助 relief valve 泄压阀 pressurization 维持大气压水平 vacuum valve 真空阀 negative pressure 负压,(4) Water Pump The water pump is used to circulate the coolant through the cooling system. It is mounted on the front of the cylinder block and driven by a timing belt. (5)Thermostat The thermostat is one of the most important parts of the cooling system, and used to keep the engine coolant at the most efficient temperature. If the coolant remains cold, it will be closed. In this case, a large amount of coolant goes to the by-pass tube without being cooled. The remaining coolant passes through the radiator to be cooled. If the coolant temperature rises to the opening point, the thermostat opens slightly. As the temperature increases further, the thermostat opens more. When the engine is under full load, the thermostat will be fully open. The maximum amount of coolant will be sent to the radiator for cooling, and a small amount will continue to flow through the by-pass tube.,timing belt 正时皮带 by-pass tube 旁通管 opening point 开启点 slightly 轻微地 load 负荷,2. Engine Lubrication System Lubrication system has been adopted to supply oil to the moving parts of this engine. The lubrication system consists of an oil pan, oil pump, oil filter, oil cooler and pressure relief valve. Fig 1-3-2 shows the parts of a lubricating system. (1) Oil pan The oil pan is located on the bottom of the engine and holds the excess oil during operation and no running conditions. A plug in the bottom of the oil pan is used to drain the oil. (2) Oil pump The oil pump is located in the crankcase area so that oil can be drawn from the oil pan and sent into the engine. (3) Oil drain plug Oil pressure relief valve is used to keep the pressure within the oil system at a constant maximum value.,lubrication 润滑 adopt 采用 supply 供给 oil pan 油底盘 drain 排放 draw 抽吸,Lubricating System （润滑系统）,Fig. 1-3-2 1-gasket（密封垫片）2-cap（加油口盖）3- dipstick（机油标尺）4guide（机油标尺导 管口）5-oil filter bracket（机油滤清器 支架）6-oil pressure switch（机油压力开 关）7-O-ring（O形圈）8-oil cooler（机油 冷却器）9-oil filter（机油滤清器）10- cap（密封盖）11-drive gear（驱动齿轮） 12-gears（齿轮）13-oil pump cover with pressure relief valve（带泄压阀的机油 泵盖）14-baffle plate（挡油板）15-oil drain plug（放油螺栓）16-seal（密封圈） 17-oil pan（机油盘）18-gasket（机油盘垫 片）19- suction line（吸油管）20- O ring（O形圈）,(4) Oil filter Oil Filter is adopted to clean the dirt particles out of the lubricating system. As the oil and dirt flow the filter unit, contaminants are trapped inside the filter unit. (5) Oil coolers Oil temperature for an engine should be in certain range of degrees. Under normal conditions, oil is cooled by the right amount of oil in the oil pan. When excess temperatures occurs, such as some heavy-duty gasoline engines and many diesel engines, oil coolers are used to keep the oil cool. (6) Oil pressure sensors and gauges Oil pressure sensors are used to sense the oil pressure in the lubricating system. Oil pressure is usually sensed directly from the main oil gallery. The value is sent to the dashboard on the vehicle and the operator can read it. The systems commonly used are a pressure gauge and an oil indicator light. The pressure gauge reads the oil pressure within the system. The oil indicator light goes on when oil pressure is lower than a certain value. (7) Marking on oil dipstick（Fig.1-3-3）,particle 粒子 contaminant 污染物 trap 收集 heavy-duty 大功率 gasoline 汽油 diesel 柴油 sense 感觉 gallery 通道 dashboard (汽车等的) 仪表板 gauge 仪表 dipst