Illustration by Ralph Hermens


Number 17 in a series of 万博登录注册万博官网登陆motorcycle learning experiences

WhenYamaha1969年,它的两冲程250cc TD2生产公路赛车投入使用,the level of over-the-counter racers was raised to that of real Grand Prix contenders.Kel Carruthers was 250cc world champion that year,and the points he earned were split between a four-cylinder four-stroke Benelli and a TD2.

和当时的TD2一样现代,在10000转/分时产生44马力,它的触发点是磁电机点火技术的由来已久。打开和关闭这些点的凸轮在曲轴的末端,其持续弯曲导致火花分散,需要非常冷的火花塞,反过来,偶尔的堵塞会污染赛车生活。Therefore,那年在代托纳,Yamaha tested two more accurate forms of ignition timing,一个基于磁传感器,另一个使用射频触发器。当时他们是个常客。

在欧洲,快速二冲程生产赛车的出现给西班牙带来了巨大的影响,where the first Femsa electronic ignition was in prototype form.通过任何实验室测试,the new Femsa was an excellent ignition because its sparks were energetic and their timing had far less scatter than a points-triggered magneto.问题是,it didn't work on the racetrack;它长期失火。

How could energetic,accurately timed sparks fail to make an engine run sweetly?有人很快就发现了问题。当两冲程气缸中的传输端口打开时,fresh fuel-air mixture jets in,和热的混合,惰性残余废气在那里旋转。因为在10000转/分的转速下,整个传输过程需要2000分之一秒的时间,所以无法进行完美的混合。The result,在气缸中火花塞间隙的任何给定点,例如,一个稳定的进程包尚未混合的气体。Here's a packet of exhaust gas.接下来是混合区,主要是惰性排气,with a bit of fresh.这里有一个干净的新鲜混合物的细胞。如果火花持续时间太短以致于整个火花放电发生在一包废气中会怎么样?那将是一次失火。在混合区呢?也可能是缺火。

我们可以想象联邦应急管理局的工程师们正在看一个显示磁电机火花放电的示波器屏幕。Magnetos build up energy in an iron magnet pole and wire coils wound onto it.线圈有电感,which means their discharge takes a while.There on the O-scope screen was the engineers' answer: a magneto,spinning on their ignition tester,在插头间隙保持一个弧1200微秒,而他们自己的电子点火器,伴随着更强烈的放电,只维持了几微秒。

磁电机的1200微秒放电相当于72度曲柄。在那段时间里,an electric arc was present,火花塞电极之间的燃烧。这样就有足够的时间让气缸气体的几个湍流单元通过间隙,确保每次都点火。


当Accel决定为顶级燃料拖拉车开发非磁电机点火装置时,它有着同样的经历。顶燃器气缸中的混合物是一种疯狂的压缩空气。各种尺寸的冷硝基甲烷液滴,以及有时间从这些水滴中蒸发的任何蒸汽。A short-duration spark can easily begin and end in an unignitable zone,产生缺火。Those old-timey Vertex magnetos sticking out of top-fuel engines were there for a good reason: They generated sparks whose long arc duration would find an ignitable zone every time.Accel extended its spark duration until results were good.

When the Femsa electronics were modified to produce longer-duration sparks,their ignitions became a must-have for riders racing the new and affordable Yamaha 250cc and 350cc two-stroke twins.德国克朗和西班牙摩托车CDIS同期出现。Soon CDI was adopted by Yamaha for its production roadracers.The revolution was under way.Only later would come today's ability to "map"点火正时,使发动机在其转速范围内的所有点都具有最佳的扭矩火花正时,leaving behind the bad compromise of fixed timing.


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