Understanding electronic ignition

Electronic engine control systems give improved performance, better machine optimisation and enhanced power delivery, compared to a mechanically controlled counterpart. But the engine you select depends on what you require it to do.

EU Stage IIIA/U.S. EPA Tier 3 equivalent and above engines within the Perkins range offer you the choice of an electronic or mechanical ignition system.

Deciding which system you need on your engine depends on what you want to use the engine for. Electronic control provides the opportunity to control the injection of fuel more accurately to optimise the power delivery and fuel consumption compared to mechanically controlled engines. However, in many cases, a mechanically controlled engine is perfectly suitable for many variable speed industrial applications, constant speed or Electric Power generation applications.

Fast response and optimised engine

An electronically controlled engine has an electronic control unit (ECU), monitoring what the engine is doing using a number of sensors – primarily engine speed – and alters the fuel injected to give the right power as it is needed.

Delivering fuel through a high pressure common rail fuel system, every injection event is controlled, both in terms of quantity of fuel and the rate of fuel injection. Multiple fuel injections can also be made into the cylinders during the compression cycle, building up fuel vapour to control the speed of the engine and its power output efficiently.

The mechanical system uses a more direct approach with a rotary or inline pump providing individual fuel bursts, one for each cylinder, normally controlled through a mechanical speed control system which open the injectors using fuel pressure. This mechanism means that flexibility in the fuel delivery is constrained, and the ability to match engine power delivery to the application requirement is more restricted.

For excavators and loaders and, to some extent, forklift trucks, the application demands a faster engine response to the load applied to make the operators’ job easier, as well as improving work rate and comfort, which is where an electronic engine brings significant benefits. Using a mechanical engine in these situations can result in reduced transient response, making the operators’ role more challenging and can also cause black smoke events under specific conditions, which it is preferable to avoid when using equipment indoors such as forklift trucks.

Machine integration

Electronic systems enable better engine/machine integration, linking not only engine but machine sensors to the ECU – enabling the right power to be delivered to the hydraulic system. When the arms and buckets of machines such as excavators or loaders operate, the power required to move them varies depending on their load. A full bucket requires more hydraulic power than an empty one. An electronic engine can be linked to sensors which measure the force and load on each of the machine components, assessing when more power is required by the hydraulic system. This enables a machine bucket to move at a similar speed when empty or full, making the operators’ role more comfortable and productive.

But electronic control systems are not necessary in all cases. Mechanically controlled engines can be cheaper and easier to maintain and they are perfectly suitable for light loaders and static equipment, such as screeders, crushers and electric power generation, where the load on the engine is fairly constant.

Meeting emissions standards

To meet Stage IIIB/Tier 3 equivalent and above emissions standards, electronic control systems are often required to ensure the combustion of air and fuel is controlled accurately. Electronically controlled systems and a high pressure common rail fuel system helps to ensure the right amount of fuel is used, and it is burnt effectively reducing the level of NOx and particulates produced. The electronic control systems are required with the management of other emissions reducing technologies such as Selective Catalytic Reduction (SCR) and Diesel Particulate Filters (DPF).

Choice depends on engine use

So the choice depends on what the engine will be used for. With heavy duty machines, you will find electronically controlled engines are generally preferred by your customers and therefore machines with those engine types will be more saleable.

To help you move to electronic engines, we offer technology integration workshops (TIWs). By working with you, we can ensure optimal integration between engine and machine.

With our TIWs you’ll get:

• Virtual exploration of packaging challenges
• Our expertise to investigate possible options and constraints
• Optimal solution selection for further development
• Differing levels of support according to your needs

We also support you during your development programmes with expert applications engineers, either directly from us, or through our Distribution network.

All Perkins engines deliver high performance. Where there is a choice between electronic and mechanical control systems, we can help deliver what your customers need.

“Providing both electronic and mechanically controlled engines is all about delivering a performance machine and helping our customers to meet their customers' needs.”
Mike Cullen, product marketing specialist