排氣凸輪軸的工藝規(guī)程及工裝設(shè)計(jì)【說(shuō)明書(shū)+CAD+3D】

排氣凸輪軸的工藝規(guī)程及工裝設(shè)計(jì)【說(shuō)明書(shū)+CAD+3D】,說(shuō)明書(shū)+CAD+3D,排氣凸輪軸的工藝規(guī)程及工裝設(shè)計(jì)【說(shuō)明書(shū)+CAD+3D】,排氣,凸輪軸,工藝,規(guī)程,工裝,設(shè)計(jì),說(shuō)明書(shū),CAD Automotive engine camshaftBrief introductionThe camshaft is a part of the piston engine. Its role is to control the opening and closingoperation of the valve. Although the camshaft rotational speed in a four-stroke engine is a half ofthe crankshaft (the same as the camshaft rotational speed in a two-stroke engine with thecrankshaft), but usually it is still very high speed, but also need to withstand the large torque, sothe design right demanding camshaft in terms of strength and support material is generally aspecial cast iron, occasionally using forgings. Valve motion law related to engine power andoperation characteristics, the design in the design process of the engine camshaft occupies a veryimportant position.StructureThe main body of the camshaft is the same as the one with the cylinder length of thecylindrical rod. The above sets have several cam for driving the valve. One end of the camshaftcamshaft bearing support and the other end is connected to the drive wheels.Cam side was egg-shaped. The design aims to ensure the the cylinder sufficient air intake andexhaust, specifically, within the shortest possible time to complete the valve opening and closingmovements. In addition, taking into account the durability of the engine and the smoothness ofoperation, the valve can not be generated due to the deceleration process of opening and closingmovements too much too large the impact of serious wear and tear of the valve, otherwise it willcause an increase in noise or other serious consequences. Therefore, the cam and the power of theengine torque output as well as the operation of the ride there is a direct relationship.Generally inline engine, a cam corresponding to a valve V-type engine or horizontal opposedtype engine, every two valves share a cam. The rotary engine the valveless with gas enginebecause of its special structure, does not need to camPositionIn the long period of time, the bottom-mounted camshaft in an internal combustion engine ismost common. Typically such engines, the valve is located in the top of the engine camshaftmachine, i.e., so-called the OHV (Over Head Valve, OHV) engines. Usually camshaft located onthe side of the crankcase, through the gas distribution agencies (such as tappet, push rod, rocker,etc.) valve control. Bottom-mounted camshaft general also called side-mounted camshaft. Fardistance valve, and each cylinder is usually only two valves in such an engine camshaft, so thespeed is usually slower, ride comfort is poor, the output power is also relatively low. However, theengine output torque and low-speed performance of this structure is relatively good, relativelysimple structure and easy maintenance.Now most of the production cars engine is equipped with overhead camshaft. The overheadcamshafts structure closer to the camshaft valve, to reduce the kinetic energy of the waste causedby the bottom-mounted camshaft due to the larger distance between the camshaft and the valveshuttle. Overhead camshaft of the engine valve opening and closing action is relatively rapid, andhence higher speed, and the smooth running is also better. The engine of the the overheadcamshafts structure appeared earlier the SOHC (Single Over Head Cam, overhead single camshaft)engine. This engine is only installed at the top of a camshaft, and therefore generally only two tothree valves of each cylinder (the intake air a to two exhaust), the high-speed performance hasbeen limited. Technology updates DOHC (Double Over Head Cam, double overhead camshaft)engine, this engine with a two camshafts per cylinder can be installed four to five valves (intaketwo to three, Pai gas two), high-speed performance significantly improved, but at the same timethe low-speed performance will be affected to some degree, the structure will be complicated anddifficult to repair.ClassificationAccording to the the camshaft number of how many, can be divided into single overheadcamshaft (SOHC) and double overhead camshaft (DOHC), two kinds. The single overheadcamshaft camshaft is only one camshaft, double overhead camshaft is two, this is toostraightforward explanation.The single overhead camshaft with a camshaft in the cylinder head, direct drive into theexhaust valve, it has a simple structure, suitable for high-speed engine. Generally used in the pastside camshaft, the camshaft in the cylinder side, is driven directly by a timing gear. The valvelifter to the rotation of the camshaft is converted into reciprocating motion of the valve must beused to transfer power. Thus, more parts of the reciprocating motion, the inertial mass, is notconducive to high-speed movement of the engine. Moreover, the slender tappet has a certaindegree of flexibility, prone to vibration, accelerated component wear, even the valve control islost.DOHC cylinder head equipped with two camshafts, one is used to drive the intake valve, theother for driving the exhaust valve. Double overhead camshaft camshaft and valve spring designless demanding, especially for the hemispherical combustion chamber of the valve V-shapedconfiguration, but also facilitate and used in conjunction with four-valve gas distribution agencies.FaultCamshaft common faults including abnormal wear and tear, abnormal wear of the symptomsoften first appear before the occurrence of abnormal sound as well as fracture, abnormal soundand fracture.(1) Camshaft almost at the end of the engine lubrication system, lubrication situation is notoptimistic. If the oil pump is too long and so insufficient oil pressure or the lubricants Roadblockage caused by lubricating oil can not reach the camshaft bearing cap fastening boltstightening torque caused by excessive oil can not enter the the camshaft gap will causing abnormalwear of the camshaft.(2) the abnormal wear of the camshaft causes the gap increases between the camshaft bearing,the camshaft movement occurs when the axial displacement, resulting in abnormal noise.Abnormal wear will lead to increased gap between the drive cam with hydraulic tappets, camcombined with hydraulic tappets will collide, resulting in abnormal noise.(3) camshaft sometimes fracture and other serious fault, common causes of hydraulic tappetcracked or severely worn, serious poor lubrication the camshaft poor quality and camshaft timinggear rupture.(4) In some cases, the failure of the camshaft is man-made causes, in particular themaintenance of the engine camshaft not correct disassembly. Such as demolition of the camshaftbearing caps with a hammer strength knocking or prying with a screwdriver, or install the bearingcap installed the wrong position does not match the result in the bearing cap and bearing, orbearing cover the fastening bolt tightening torque is too large. Install bearing cap should payattention to the direction of the arrow and the position number marked on the surface of thebearing cap, and in strict accordance with the provisions of torque using the torque wrench tightenthe bearing cap fastening bolts.RefitIn order to enhance the power of the engine, some converted stores a modified camshaftengine face lift high angle camshaft (Hi-camshaft CAM) is a common form of modified method.This modification operation is not complicated, but because of the lack of understanding of somemodification cam on the camshaft angle and works so that the modified effect is not obvious evenlead to the deterioration of the performance of the engine.High angle camshaft relative to ordinary camshaft cam angle of about 240, high anglecamshaft cam angle can often reach over 280. The large angle of the camshaft can extend thevalve open time, increase the valve lift, the intake valve and the exhaust valve open as early andlate off, so that more air into the cylinder, in order to improve the engine, the power of the highspeed output. Should choose for civilian vehicles, modified cam camshaft angle 278, will be asignificant increase in working an angle greater than 278camshaft valve overlap angle, so thatthe power of the engine high speed improve a lot, but engine cylinder seal is not good at low speedand cause the idling serious jitter or even turn off, so that the vehicle can not adapt to everyday use,and can only be used for competition purposes.Production technologyThe camshaft is one of the key parts of the engine, the hardness of the camshaft peach apicaland white layer depth is to determine the key technical indicators camshaft life and engineefficiency. , Should be considered to ensure that the cam has a sufficiently high hardness and afairly deep white layer premise journal does not appear high carbide, so that it has a better cuttingperformance.Currently, the main method of domestic and foreign production camshaft: steel forging blankby cutting the cam peach tip martensitic layer formed some of the high-frequency quenchingprocess. The end of the 1970s, Germany and France have developed a new camshaft argon arcremelting process; hardened cast iron camshaft otherwise dominated by the United States; chilledcast iron camshaft mainly to Japan and France; well cam parts of the Cr-Mn-Mo alloy coatingscasting surface alloying production.