How VTEC Works – A Simple Explanation

How VTEC Works – A Simple Explanation


大家好 欢迎观看 现在我正被 VTEC 环绕 这台 S2000 装有 VTEC 这台本田雅阁也有 我面前这台本田思域 Type R 的引擎也有 本期视频我们将讲解什么是 VTEC(可变气门正时与扬程电控系统),以及它如何运转 要了解 VTEC,我们要先了解引擎 引擎至少需要三个要素才能工作 空气、燃料与压缩 至于像这台思域 Type R 的汽油发动机 你还需要火花塞来点火 在引擎需要的这四个要素中,VTEC 是针对空气的技术 现在我们知道了引擎工作需要什么 那么引擎的工作流程由四个冲程构成 第一冲程是进气,活塞向下运动,吸入空气和燃料 第二冲程是压缩,活塞向上运动,压缩刚才吸入的油气混合物 第三冲程是做功,火花塞点燃油气混合物,推动活塞向下移动 最后是排气冲程,活塞向上移动,将刚才燃尽的气体排出 VTEC 可以在这些冲程中优化空气流动 它可以在进气冲程起效,也可以在排气冲程起效 通过 VTEC,你可以让引擎充分利用空气 在分析 Type R 引擎之前,我们先来看看这个简化的例子 这是一个气缸盖 上面有气门,可以让空气流进流出气缸 这是进气门,可以让空气进入 这是排气门,可以让空气流出 气门可以张开多大,取决于这个凸轮轴 凸轮轴的功能是开合气门 这是凸轮轴上的一个凸轮 轮轴转动时凸轮跟着旋转 凸轮轴转动时,凸轮会推开气门 这个凸轮越高,它就能将气门顶得越高 气门顶开得越大,流经引擎的空气就越多 你加入引擎的空气越多,燃料越多,你获得的动力就越大 现在我们来看这台 Type R 引擎上的气门是如何工作的 我们可以看到这里有两根不同的凸轮轴,一根在这,另一根在这 普通的凸轮轴就像这条 你用来开合气门的凸轮只有一种高度 至于这边的 VTEC 凸轮轴,它用来开合这些气门的凸轮有数种不同的高度和宽度 我们看,这个是 VTEC 的凸轮轴 这两个气门由这条凸轮轴负责开合 你可以看到,它可以选择两种不同的凸轮高度 它可以用中间这个高的凸轮 它也可以用两边低的凸轮 它会同时使用两个凸轮打开气门 它可以切换使用两种不同的凸轮 那么你为什么要用这个低的凸轮? 你在低转速时用这个低的凸轮 在低转速时你并不需要那么多的空气 因此你用低凸轮,这样空气就进来得更快 你限制气流,就会增加流速 空气流动越快,它和燃料混合就越均匀 混合越均匀,燃烧效率就越高 在高转速时,你希望获得尽可能多的动力 你希望进入引擎的空气尽可能多 你就用中间这个高的凸轮 它可以让气门开得更大,推动更多空气进入引擎 燃烧更多燃料,产生更多动力 那么 VTEC 又是如何工作的? 在低转速时,两侧的低凸轮如之前所说,负责开合气门 它通过推动这些摇臂来控制气门 中间的这个摇臂和两侧的摇臂并没有连接 所以尽管中间的凸轮在推动中间的摇臂上下移动 因为它没有连接到两侧的摇臂 只有两侧的摇臂才连接到气门上 所以它并不控制气门的开合 起效的是两侧的低凸轮 当引擎的转速升起来后,你就要用到中间的高凸轮 在高转速时,油压会推动一个小活塞,把这些摇臂锁定起来 之前这个高凸轮只是推动中间的摇臂上下运动,并没有其它效果 现在它和两侧的摇臂锁定,进而连接到气门 现在中间的高凸轮就负责开合两侧的气门 因为它高度更高,气门的开口就更大 你也可以继续用油压控制这个小活塞锁定或解锁这些摇臂 选择你想用的凸轮 如果你仔细观察,你会发现这个引擎只有排气侧有 VTEC 它只控制排气门 而上面的进气侧只有一种凸轮 这和本田之前的许多高性能引擎不同,它们在进排气侧都有 VTEC 为什么这台引擎只有排气侧有 VTEC? 原因是这台引擎有涡轮增压,你可以看到这是增压器 涡轮增压器可以轻松地将空气压入引擎 它在进气侧不用额外的高气门就可以轻易将空气压入 不过燃烧后,空气体积膨胀 气缸内压力非常高 用高凸轮可以促进空气排出 另外一个原因是,除了排出高压气体,你还要推动气体驱动涡轮增压器 使用高气门,气体可以更容易排出,推动涡轮,进而从排气口排出 感谢收看,如果你有疑问或意见,欢迎在下面留言

100 Replies to “How VTEC Works – A Simple Explanation”

  1. It seems weird to me that even though there is a turbo, they still decided not to put VTEC on the intake side. If it's more advantageous to have it on the intake without a turbo, then why wouldn't it be just as advantageous with the turbo. Does not make sense to me. I find it hard to believe there is zero gains from having VTEC on the intake with a turbo.

  2. Yeah but what about the semi boloid slots of the stator?
    How does it deal with the side fumbeling?
    So many questions…

  3. Honda’s fans always talk about VTEC like something “magical” “super mega highly tech” your car could deploy wings and fly but for them VTEC is the most.

    Now I know its only two options to open the valve. ( I though it was a smart systems with “infinite” opening dimensions) 😂

    Those guys are a joke 🙆🏻‍♂️

  4. man you just gave an incredibly understandable explanation for what was the most unknown thing in my live
    Thanks a lot for this video!

  5. The Fiat Multiair is a more modern variant of variable valve timing.
    In the past, the Honda system was certainly a very unique system, but has since become obsolete.
    Search Fiat Multiair for explanation

  6. Great video! I have worked on theses a few times, Honda does a fantastic job no question, this engine is a great bullet proof package. Have you done a video on sliding cam technology? That would be a good one to explain also, thanks.

  7. Any chance you could do a review of the C4 ZR-1 with the real LT5 5, 4 Cam 32 Valve Motor designed by Lotus , built by Mercruiser .

  8. Ive been a Honda technician for almost 20 years. This video should be used by Honda for their techician training for noobs. It is better than theirs. LOL

  9. I have a 2011 Honda Element with a V-TEC motor. I had a totally different idea about how they work. Mine is normally aspirated and I thought the cam timing was adjusted to give more overlap between the exhaust and intake valves.

  10. nice to see a video without a dry erase board with formulas , and an actual tech mechanical view. even though i already knew what this was.

  11. Maybe that’s why the new earth dream engines are have fuel mixing with the oil. What happens when it happens too much. A blown engine.

  12. If you have a weak oil pump, does it effect the Vtec ? Is there an adjustment for the VTEC to kick in? Thanks for the video, I always wondered how it worked.

  13. This really is a very good illustration and explanation. I watched one car show on TV, the one with those two brits, the short chubby guy and the taller lean guy that did all the work. He showed how this works on the top of an engine he had exposed. Pretty clever

  14. Soon, and already in some vehicles and trucks there will NOT be a cam shaft. They electric operated valves that open and shut. No camshaft, no push rod, so much less engine force lost due to friction and pushing against valve springs. Diaphram type valves, slit valves, sliding valves, etc. types are out there. There are many ways to open and close a valve port different than the current designs that push a valve up and down against a valve seat. These new valves allow for continuous adaptation, and opening and closing under computer control.

  15. Your explanation is just fab but i have a question, how would you know that this much air is being compressed by the turbocharger and all right, i have to allot this much height to cam profile in between the other two cams.

  16. Hey, injustice recently did a seafoam treatment on a 2015 Subaru forester normally aspirated engine. To clear the check engine code I disconnected the battery. It runs great before battery disconnect. Now the car wont idle it shacks and it wants to idle at 500 600 rpm and two times it stalled. Any way I can clean the throttle body and have it relearn new idle ?

  17. So does using a thicker oil like 20-50 make VTech work at lower rpms? Or is the oil passage that pushes the higher lobe into action only open at certain rpms? Like a valve opens at 3000 rpm allowing the oil to flow into the system.

  18. I hate vtec. I want full power no matter the RPM range. I hate it in my ridgeline, and I hated it when I owned a 2003 VFR motorcycle. VTEC is just an EPA pleasing technology. I giggle when youngsters brag about their VTEC engines. "Yay, I drive around a vehicle that only has power above 4000 rpms!"

  19. But why not just use the higher profile only for the exhaust rather than having two profiles? Its just exhaust why does it matter to take difference for exhaust for low rpm and high rpm as its turbo charged.

  20. Every time I see those shafts and components, I start worrying about engine wear. I mean those parts are really scratching each other every single turn. That hurts!

  21. Hello , how the piston lock valves? i know is because of the oil pressure at high power but what is the mechanism to get lock?

  22. I don't understand. Once the VTEC kicks in at higher rpm's, how come there's no valve float with the two lower rpm lobes since the valves are lifted higher off the lobes?

  23. Nice job YouTube. Been searching for p2646 error and this recommendation is spot on. I was curious how it worked when I replaced my spool valve.

  24. I find the VTEC in my R18 kicks in at about 2200 rpm in second gear. I wonder how viscosity breakdown in my oil over time affects the ability for the engine to push the vtec pin in to change the cam profile. Specifically, I wonder if dirty, thin oil makes it more difficult for the engine to engage the VTEC cam profile, and if so would increasing the viscosity with an additive lower the point at which VTEC engages.

  25. As an Acura TL owner, I appreciate this V-tech explanation. It prompts a question. Given this level of complexity, why doesn't this system fail more often?

  26. Not only lifted higher, but opened a bit earlier and closing bit later, because the cam lobe is little bit fatter than normal one.

  27. I'd always wondered how that worked. A mechanic told me it was done with oil pressure but didn't go into detail like this video did. Thanks, it's no longer a mystery.

  28. You explain the reason for VTEC to speed air intake for better mixing with fuel. And later you show that engine has it only on exhaust.

  29. Forgot to mention it also eliminates the need for an EGR because it can keep the exhaust valve open slightly during the intake stroke allowing some exhaust back in to water down your air fuel mixture to keep combustion temperatures down so NOx doesn't form. Also you forgot to mention that nearly every modern vehicle has various forms of VVT (variable valve timing) and that VTEC doesn't make you special lol…even when it kicks in yo.

  30. so the lobe hits the camshaft that opens the air which forces the valve to push first through the two profiles that makes more power because of a better fuel mixture. I would like two of these please

  31. Would you say VTEC is primarily for high power output at high revs or improved economy at lower revs? Or is it both benefits at the same time?

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