Dual ignition


Dual ignition
Dual ignition
Hirth 2702V.JPG
A Hirth 2702 twin-cylinder, two-stroke aircraft engine. Equipped with dual ignition, the photo shows the two spark plugs per cylinder.

Dual Ignition is a system for spark-ignition engines, whereby each cylinder has every critical ignition component duplicated, including spark plugs, magnetos and ignition circuits, rather than the more usual single spark plug or circuit. It is commonly employed on both two-stroke and four-stroke aero engines[1][2] and is sometimes found on cars and motorcycles.

Dual ignition provides two advantages: redundancy in the event of in-flight failure of one ignition system and more efficient burning of the fuel-air mixture within the combustion chamber.[1][2] In aircraft, redundancy is the most important consideration, but in other vehicles combustive efficiency is the prime aim.

Design

The provision of dual ignition in aero-engines is a safety feature to allow an aircraft to continue flying and land safely after an ignition system failure. Operation of aero engines on one magneto (rather than both) typically results in an rpm drop of around 75 rpm.[2]

While true dual ignition uses completely separate and redundant systems, some certified engines, such as the Lycoming O-320-H2AD use a single engine magneto drive-shaft turning two separate magnetos. Whilst saving weight, this creates a single point of failure that could cause both ignition systems to cease working.[2]

Another form of partial dual ignition that has been used on amateur-built aircraft uses a single spark plug, but duplicates the coil and pick-up for better redundancy than traditional single ignition.[3]

A further form of dual ignition on motorcycles has twin plugs but a single coil per cylinder. The HT current does not return via earth but via a second HT lead on the second plug. This system allows the cylinder to fire even if one plug becomes fouled; and the continuing combustion may burn off deposits, possibly enabling the fouled plug to clear.[citation needed]

Dual ignition promotes engine efficiency by initiating twin flame fronts, thereby obtaining faster and more complete burning and increasing power.[4] Although a dual ignition system is a very effective method of achieving optimum combustion and better fuel consumption, it remains rare in cars and motorcycles because of difficulties in siting the second plug. Alfa Romeo Twin Spark cars (by definition) use dual ignition, as do some motorcycles, such as the Honda VT500 and the Honda NT400 Bros[citation needed].

Wankel engines have such an elongated combustion chamber that even non-aero wankel engines may adopt dual ignition to promote better combustion. The MidWest AE series Wankel aero-engine has twin plugs per chamber, but these are placed side-by-side, not sequentially, so their main purpose is to give redundancy rather than improved combustion[5].

References

  1. ^ a b Crane, Dale: Dictionary of Aeronautical Terms, third edition, page 177. Aviation Supplies & Academics, 1997. ISBN 1-56027-287-2
  2. ^ a b c d Aviation Publishers Co. Limited, From the Ground Up, (27th revised edition), page 67, ISBN 09690054-9-0
  3. ^ Jodel.com (undated). "Dual ignition on auto engines without dual plugs". http://www.jodel.com/index.asp?p=dualignition&engines. Retrieved 2 August 2011. 
  4. ^ van Elderen, Jan (2002). "Raceservice4u Twin plug systems". http://www.raceservice4u.com/Twin%20plug.htm. Retrieved 5 August 2011. 
  5. ^ MidWest Engines Ltd AE1100R Rotary Engine Manual

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • dual ignition — noun : automobile ignition by two independent currents from a battery and from a magneto …   Useful english dictionary

  • dual ignition system — See twin ignition system …   Dictionary of automotive terms

  • Ignition system — For other uses, see Ignition system (disambiguation). An ignition system is a system for igniting a fuel air mixture. Ignition systems are well known in the field of internal combustion engines such as those used in petrol (gasoline) engines used …   Wikipedia

  • ignition — A process which initiates the combustion of the compressed air/fuel mixture in the combustion chamber. In a spark ignition engine, the mixture is ignited by an electric spark; in a diesel engine, the self igniting mixture must be preheated by… …   Dictionary of automotive terms

  • Ignition coil — Bosch ignition coil. Dual ignition coils (blue cylinders, top of picture) on a …   Wikipedia

  • ignition system — The system that provides the electrical current or spark to ignite the air fuel mixture in the combustion chambers. It includes the battery or magneto which sends electricity to the ignition coil if the ignition switch is on. The coil amplifies… …   Dictionary of automotive terms

  • Dual Shock — DualShock DualShock est une gamme de manette de jeu officiel des consoles Playstation de Sony. Son nom fait référence à la présence de doubles moteurs solénoïdes, qui permettent de générer des vibrations dans le contrôleur. Elle comprend trois… …   Wikipédia en Français

  • Dual Shock 2 — DualShock DualShock est une gamme de manette de jeu officiel des consoles Playstation de Sony. Son nom fait référence à la présence de doubles moteurs solénoïdes, qui permettent de générer des vibrations dans le contrôleur. Elle comprend trois… …   Wikipédia en Français

  • Dual Shock 3 — DualShock DualShock est une gamme de manette de jeu officiel des consoles Playstation de Sony. Son nom fait référence à la présence de doubles moteurs solénoïdes, qui permettent de générer des vibrations dans le contrôleur. Elle comprend trois… …   Wikipédia en Français

  • Dual shock 3 — DualShock DualShock est une gamme de manette de jeu officiel des consoles Playstation de Sony. Son nom fait référence à la présence de doubles moteurs solénoïdes, qui permettent de générer des vibrations dans le contrôleur. Elle comprend trois… …   Wikipédia en Français


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.