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Primary versus Secondary Circuits

(2010-07-29 10:14:07)
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杂谈

Primary versus Secondary Circuits

主要与次级回路

   用于汽车解决方案

In this tutorial we will be looking at the relationship between the Primary picture and the Secondary HT output, and monitoring spark burn times and HT voltages.

在本教程中,我们将观察在初级波形和次级HT输出之间的关系,和监测火花燃烧时间和HT电压。

图1

Primary <wbr>versus <wbr>Secondary <wbr>Circuits

 

The example waveform(图1)shows the exact relationship between the ignition's primary circuit and the secondary output. The primary circuit transfers its characteristics into the secondary through ‘mutual inductance’ and will mirror the primary exactly.

这个示例波形显示了初级点火电流和次级输出之间的关系。初级电流通过互感被反应到了次级线圈。

The blue trace shown in the example is the Low Tension (LT) signal, measured from the coil's negative terminal (marked number 1). The red trace is the High Tension (HT) output voltage measured at the king lead. In the example, both waveforms show exactly the same burn time of 2 milliseconds (ms).

本例中从线圈的负端(标记为端子1)测到的信号轨迹(以蓝色标示)是低张力信号。从另一通道测得的以红色标记的信号时高张力输出电压信号。这两个波形都精确地显示燃烧时间时2ms.

Situated within the coil's primary winding is the secondary winding. This winding is coiled around a multi-laminated iron core and has approximately 20,000 to 30,000 turns. One end is connected to the primary terminal and the other to the coil tower. The High Tension (HT) voltage is produced by mutual induction between the primary winding and the secondary winding, and the central soft iron core intensifies the magnetic field between them.

与初级绕组对应的是次级绕组。这是一个多层压制铁心,拥有约20,000至30,000匝。一端子连到主终端,另一端子连接和线圈搭铁。通过初级绕组和次级绕组之间的互感产生出一个高电压,把两绕组联系起来的中心软体起导磁的作用,它把磁场集中起来。

On a distributor system, the secondary HT voltage produced by the coil is allocated to the appropriate spark plug via the contacts inside the distributor cap. This system is quickly becoming obsolete due to the introduction of the DIS and coil per cylinder systems with fewer moving parts and wear factors. The voltage measured at the spark plug is the voltage required to jump the plug gap in varying conditions, and will be determined by any of the following:

对于一个分接器系统,次级高压电被引到了合适的火花塞,通过在分电器内部的接触。该系统正在迅速落伍,由于DIS和有更少运动部件和磨损因素的每罐线圈的引入,测量火花塞的电压是要求在不同条件下能跳掉插头。和这个电压受以下条件的约束:

 

促使电压升高的条件:                    促使电压降低的条件:

大的插头间隙                            小的插头间隙

大的转子气隙                            低压缩

一个插头的断裂                          丰富的混合物

一个枢纽的破坏                          错误的点火时间

中心监管的一个失误                      用于地面触发

一简洁的混合物                          插头插得不对。

转子的失调                              

The plug kilovolt (kV) requirement of older engines tends to be lower than that of the modern engine, as the later designs will run higher compression ratios, leaner air/fuel ratios and have larger spark plug gaps. The modern engine with Distributorless Ignition System (DIS) has all the advantages of a constant-energy electronic ignition system, but with the added bonus of the distributor cap, king lead and rotor arm being eliminated from the system. Reliability problems from dampness and tracking are now almost eliminated. DIS has its own drawbacks by having half of the plugs firing with an acceptable negative voltage, while the other half is fired by the less acceptable positive polarity. This will have the effect of pronounced plug wear on the positive fired plugs.

旧的发动机要求的接口KV高电压倾向于比现代引擎更低,由于后来的设计将运行更高的压缩比、更精简的空气/燃料比,和有更大的火花塞间隙。带有分电器点火系统(DIS)的现代引擎拥有恒定能量电子点火系统的所有优点,但随着分电器帽优势的增加,铅棒和转子臂渐渐被淘汰掉了从系统中。现在潮湿和跟踪的可靠性问题几乎全部被解决了。DIS有自身的缺点,由于有一半的插头接通一个可接受的负电压,而另一半接通不太能接受的正极。这有两端击穿的效果。

This system, because of its nature, will fire the plugs each revolution, instead of every other, and is known as a wasted spark system. This does not mean that the plugs will wear at twice the normal rate, as the wasted spark is on the exhaust stroke, and is therefore under no compression. If the spark plugs are removed after several thousand miles and examined, it will show that two of the plugs have relatively square electrodes, while the plugs that have been fired positive will have pronounced plug wear.

这个系统,由于它的自然属性,将会点火那个活塞在每一次气缸过程,是一个有名的火花浪费系统。这并不意味着活塞将以两倍于正常速度上下运动,因为浪费的火花出现在排气行程中,和没有任何压缩。如果火花塞在几千英里的行程和测试后被移除,那么有两个活塞相对地有方形电极将显示出来,这时活塞在运动。

 

Secondary voltages and Waveforms

次级电压及其波形

The ignition secondary picture shown in the example waveform (Figure_2) is a typical picture from an engine fitted with electronic ignition. The waveform is an individual secondary High Tension (HT) picture that can be observed one cylinder at a time.

图2

Primary <wbr>versus <wbr>Secondary <wbr>Circuits

 

二次点火波形(如Figure_2所示)是一个来自装有电子点火装置的引擎的典型波形。该波形是单个的二次高压电波形,可以被观察到以一个气缸一次的频率。

The secondary waveform shows the voltage required to jump the plug's electrode (A), and (B) the length of time that the HT is flowing across the spark plug's electrode after its initial voltage to jump the plug gap. This time is referred to as either the ‘burn time’ or the ‘spark duration’.

次级波形显示了A通道所需的点火电压,上述水平电压线长度是'火花持续时间'或'燃烧时间'

In the illustration shown, it can be seen that the horizontal voltage line in the centre of the oscilloscope (C) is at fairly constant voltage of approximately 3 kV. This voltage is referred to as the Sparkline kV. This voltage is the voltage required to maintain the spark flow across the plug's electrode, and is determined primarily by the secondary resistance within the HT circuit. From the 0 ms point on the scope to point D is the spark duration, in this case around 1 milliseconds. The waveform is then seen to drop sharply into what is referred to as the ‘coil oscillation’ (E). The coil oscillation should display a minimum number of peaks (both upper and lower) and at least of 4 - 5 peaks should be seen. A loss of peaks on this oscillation shows that the coil needs substituting. An example of a faulty coil and the subsequent loss of oscillations can be seen in图3. The oscillation seen at point (F) is called the ‘polarity peak’; this voltage will be of the opposite polarity to the plug firing voltage as this is created when the magnetic flux is initially built, or at the start of the dwell period.

图3

Primary <wbr>versus <wbr>Secondary <wbr>Circuits

 

在图中,我们能看到在示波器中心有一条大约3KV的水平稳定的电压线。这个电压即燃烧线电压。这个电压被要求到维持火花通过活塞电极,和主要被高压回路即次级线圈电阻决定。从示波器的0ms点到D点是火花持续时间,在本例中大约是1ms.然后看到波形急剧下降进入“线圈振荡”过程,这个过程至少要有4到5个极点(峰)包括上下顶。一峰在此振荡中损失表明线圈需要更换。线圈的一个错误的例子,和以后振荡中的损失可以看到在图3中。在F点处看到的振荡称为'极峰',这将是相反极性的火花塞电压,因为这个电压是在磁通量刚建立不久或者说在闭合时间的开始时创立。

SAAB CDI Ignition

萨博电容放电点火

This particular system is different from the conventional magnetic inductive system and is called Capacitor Discharge Ignition (CDI). CDI was used on a few vehicles in the late 60s early 70s, but is now seeing a revival in this innovative system.

这种点火方式与传统的通过电磁感应产生高电压点火方式不同,被称为电容放电点火(CDI)。CDI被用在少数车辆上,在60年代末70年代初,但现在看到了它在这个创新体系中的复苏。

The ignition pack consists of individual coils that are mounted directly onto the spark plugs and are housed in a ‘cartridge’ , located between the engine's camshafts. As well as housing the ignition coils and spark plug connectors, the cartridge also contains the capacitor and the charging transformer, plus some other circuitry, as Direct Current (DC) voltage cannot be multiplied by a transformer until it has been converted into Alternating Current (AC) voltage — usually by means of a oscillator.

点火包包含个人线圈,线圈被直接安装到火花塞和被放于墨盒里,位于发动机的凸轮轴之间。谈到点火线圈和火花塞连接器,墨盒还包含电容器和充电变压器,加上其他一些电路,因为直流(DC)电压不能通过一个转换器实现乘法运算,要转换成交流(AC)电压才行,通常通过一个振荡器的方式。

The 400 volts contained within the capacitor will be discharged into the appropriate coil from signals received from the Electronic Control Module (ECM). This is mainly where this system differs from the conventional ‘Coil per Cylinder’. The 400 volts are discharged to the positive terminal of the coil and the coil negative is a permanent earth. Where as a typical system will supply 12 volts to the positive terminal of the coil and 400 volts is seen on the negative side from inductance.

电容上的400V将装载到合适的线圈,而这线圈从ECM接收信号。这是这个系统与传统的每罐一线圈系统的最大不同之处。出来的400伏特被接到线圈的正极,线圈的负极接地。

All of the connections in and out of the cartridge are at 12 volts or less and primarily terminate at the ECM. When the engine is cranked, the ECM will fire cylinders 1 and 4 together and cylinders 2 and 3 as wasted sparks, with every Top Dead Centre (TDC), until the ECM has determined which cylinder is on the combustion stroke (as opposed to the exhaust stroke). The ECM takes its reference from a Hall effect sensor that is located to the rear of the front pulley.

进出墨盒的所有连接都是12V或者更少,主要是和ECM相连。当发动引擎时,ECM将对1和4气缸点火,2和3气缸的火花持续伴随着顶部死区,直到ECM决定了哪个气缸是在燃烧过程。ECM以位于前方滑轮后边的霍尔效应传感器为参考。

To aid starting when low cranking speed is seen, the ECM will continually fire the plugs up to 60° after TDC with a continual arc across the spark plugs' electrodes. This process will continue until the engine speed reaches 850 rpm.

当看到摇转速度低时,为了帮助启动,ECM将继续点火火花塞,温度上升到60度以后,TDC将有一个连续的电弧跨过火花塞的电极。这个过程会持续到引擎速度达到850转每分钟。

If the engine fails to start and the ignition key is returned from the crank position, a sequence of sparks are fired across the plugs to free them from any fouling and to clear any excess hydrocarbons left in the cylinders. Great care needs to be taken when working on secondary ignition systems and even more so on this particular one!

如果引擎无法启动,那么点火关键是回到曲轴位置,一系列点着的火花没有制造任何污垢,和清除了任何留在气缸里的任何多余的碳氢化合物

图4 shows a direct ignition system, as used by Saab.(一个萨博的直接点火系统)

图4

Primary <wbr>versus <wbr>Secondary <wbr>Circuits


如需了解更多有关汽车示波器的知识或者购买汽车示波器的话,可以登录我们的网址:http://www.hkaco.com 

       或者拨打电话: 020-38743030  联系我们!      

 广州虹科电子科技有限公司

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