【正文】 畢業(yè)設計 發(fā)動機基本原理 汽車已經工作的非常成功通過電子馬達，蒸汽機，和內燃機，內燃機在氣缸里燃燒并且將燃料燃燒發(fā)出的膨脹力轉換或旋轉力用來推動汽車。overlap. The inlet valve remains open until some 50176。 they are “attached” to your legs. The pedals are attached to the bicycle crank which is like the crank shaft, because it turns the wheels. To reverse this, the pistons (legs) are attached to the connecting rods ( pedals ) which are attached to the crankshaft (the bicycle rank). The power from the bustion in the cylinders powers the from the bustion rods to turn the crankshaft. Connecting rod： The connecting rod shown in is made of fed high strength steel. It transmits force and motion from the piston to the crank pin on the crankshaft. A steel piston pin, or “wrist pin”, connects the small end of the connecting rod. Some rods have a lock bolt in the small end. As the piston moves up and down in the cylinder, the pin rocks back and forth in the hole, or bore, in the piston. The big end of the connecting rod is attached to a crank pin by a rod bearing cap. 天津職業(yè)技術師范大學 2021屆本科生畢業(yè)設計 Connecting rod and rodbearing caps are assembled during manufacture. Then the hold for the bearing is bored with the cap in place. This is called linebring. It make each rod and its cap a matched set. Usually, the same number is stamped on the rod and cap. This prevents the caps setting mixed during engine service. If the caps are mixed, the bearing bore will not be round. An engine assembled with the rod bearing caps switched will probably lock the crankshaft. If the crankshaft turns, the bearing will probably have improper clearance and early bearing failure will result. Another reason for keeping the cap and rod matched is to prevent engine unbalance and unwanted vibration. All connecting rods in an engine must be as light as possible. But they must all weigh the same. If one rod is heavier than the other, the engine will vibrate. This could damage the engine. Crankshaft The crankshaft then main rotating member, or shaft , in the engine. It has crankpins, to which the connecting rod from the pistons are attached . During the power strokes, the connecting rods force the crankpins and therefore the crankshaft to rotate. The reciprocating motion of the pistons is changed to rotary motion as the crankshaft spins. This rotary motion is transmitted through the power train to the car wheels. The crankshaft is a strong, onepiece casting, or fing, or heattreated alloy steel. It must be strong to take the downward force of power strokes without excessive bending. It must be balanced so the engine will run without excessive vibration. Engine Operating Principles Most automobile engines are internal bustion, reciprocating 4stroke gasoline engines, but other types have been used, including the diesel the rotary (Wankel), the 2stroke and the stratified charge. Reciprocating means “up and down” or “back and forth”. It is the up and down action of a piston in the cylinder that produces power in a reciprocating engine. Almost all engines of this type are built upon a cylinders block, or engine block. The block is an iron or aluminum casting that contains engine cylinders and passages called water jackets for coolant circulation. The top of the block is covered with the cylinder head, which forms the bustion chamber. The bottom of the block is covered with an oil pan or oil sump. 天津職業(yè)技術師范大學 2021屆本科生畢業(yè)設計 Power is produced by the linear motion of a piston in a cylinder. However, this linear motion must be changed into rotary motion to turn the wheels of cars and trucks. The piston is attached to the top of a connecting rod by a pin, called a piston pin or wrist pin. The bottom of the connecting rod is attached to the crankshaft