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1、可变气门配气相位和气门升程电子控制系统VTEC技术解析the camshaft and rocker arms, but unlike ordinary engine is the number and control method of cam and rocker arm. Medium and low speed with a small angle of the cam, two valve timing and lift different at low speed, this time a valve lift is very small, almost do not partic
2、ipate in the intake process, the air intake channel basically the equivalent of two valve engine, but due to the flow direction of an intake air barrier gas cylinder center, so it can produce intake eddy current, strong for low speed, especially in the cold car conditions conducive to improving the
3、mixture uniformity, increases the burning rate and decrease the effect of wall surface chilling effect and clearance, making the combustion more fully, thereby improving the economy, and significantly reduce HC and CO emissions; and at high speeds. Through to VTEC solenoid valve to control the hydra
4、ulic oil, so that the two intake rocker arms are connected as a whole and the intake cam from the opening of the longest and largest lift to drive the valve, this time two inlet valve according to the cam profile synchronization. Compared with the low speed operation, greatly increasing the inlet fl
5、ow area and opening duration, so as to improve the power of the engine at high speed. This two kinds of entirely different performance curve of output, Honda engineers so that they are implemented in the same engine, and vividly described as the usual soft driving and wartime intense driving.But VTE
6、C system for gas distribution phase change is still the stage, that is to say the change with gas phase only at a speed jump, but not in a speed range of continuous variable. In order to improve the performance of VTEC system, Honda constantly innovate, introduced the i-VTEC system.Simply put, the i
7、-VTEC system is based on VTEC, added a called VTC (Variable timing control variable timing control device) - a group of inlet valve camshaft timing variable control mechanisms, i.e. i-VTEC=VTEC VTC. At this point, the exhaust valve timing and overlapping time open is variable, controlled by VTC, int
8、o the VTC mechanism so that the engine can have suitable gas distribution phase in large range of speed, which improves the performance of the engine to a large extent.A typical VTC system by the VTC actuator, VTC oil control valve, all kinds of sensors and ECU components. The VTC actuator, VTC oil
9、control valve can generate action according to the ECU signal, the phase of inlet camshaft continuous change. VTC makes the valve overlap time more accurately, ensure the intake valve and exhaust valve, the best lap time, can improve engine power 20%.由本田汽车开发的VTEC是世界上第一款能同时控制气门开闭 时间及升程两种不同情况的气门控制系统，现
10、在已演变成i-VTEC。 i-VTEC发动机与普通发动机最大的不同是，中低速和高速会用两组 不同的气门驱动凸轮，并可通过电子系统自动转换。此外，发动机还 可以根据行驶工况自动改变气门的开启时间和提升程度，即改变进气 量和排气量，从而达到增大功率、降低油耗的目的。韩国的汽车工业一向不以技术先进闻名，所以所用技术也多是借鉴 了德、日等国的经验，而CVVT正是在VVT-i和i-VTEC的基础上研 发而来。以现代汽车的CVVT引擎为例，它能根据发动机的实际工 况随时控制气门的开闭，使燃料燃烧更充分，从而达到提升动力、降 低油耗的目的。但是CVVT不会控制气门的升程，也就是说这种引 擎只是改变了吸、排气
11、的时间。VTEC发动机每缸有4气门（2进2排）、凸轮轴和摇臂等，但与普通 发动机不同的是凸轮与摇臂的数目及控制方法。中、低转速用小角度 凸轮，在中低转速下两气门的配气相位和升程不同，此时一个气门升 程很小，几乎不参与进气过程，进气通道基本上相当于两气门发动机， 但是由于进气的流动方向不通过气缸中心，故能产生较强的进气涡 流，对于低速，尤其是冷车条件下有利于提高混合气均匀度、增大燃 烧速率、减少壁面激冷效应和余隙的影响，使燃烧更加充分，从而提 高了经济性，并大幅降低了 HC、CO的排放；而在高转速时，通过 VTEC电磁阀控制液压油的走向，使得两进气摇臂连成一体并由开启 时间最长、升程最大的进气凸
12、轮来驱动气门，此时两进气门按照大凸 轮的轮廓同步进行。与低速运行相比，大大增加了进气流通面积和开 启持续时间，从而提高了发动机高速时的动力性。这两种完全不同性 能表现的输出曲线，本田的工程师使它们在同一个发动机上实现了， 并且形象地称之为“平时的柔和驾驶”与“战时的激烈驾驶”。但是VTEC系统对于配气相位的改变仍然是阶段性的，也就是说其改 变配气相位只是在某一转速下的跳跃，而不是在一段转速范围内连续 可变。为了改善VTEC系统的性能，本田不断进行创新，推出了 i-VTEC 系统。简单地说，i-VTEC系统是在VTEC系统的基础上，增加了一个称为 VTC（Variable timing control4可变正时控制”）的装置 一组进气门 凸轮轴正时可变控制机构，即i-VTEC=VTEC+VTC。此时，排气阀 门的正时与开启的重叠时间是可变的，由VTC控制，VTC机构的导 入使发动机在大范围转速内都能有合适的配气相位，这在很大程度上 提高了发动机的性能。典型的VTC系统由VTC作动器、VTC油压控制阀、各种传感器以 及ECU组成。VTC作动器、VTC油压控制阀可根据ECU的信号产 生动作，使进气凸轮轴的相位连续变化。VTC令气门重叠时间更加 精确，保证进、排气门最佳重叠时间，可将发动机功率提高20%。
