Fresh emissions legislation invariably incurs added cost for automakers, but Delphi engineers believe their latest range of optimized GDi (Gasoline Direct Injection) technologies will make a significant contribution to overall hardware cost savings for engines meeting Euro6 requirements and beyond.
The new GDi components have been designed to match the performance capability of piezoelectric injection components but with what the company terms a “significant” cost advantage. Says Delphi Powertrain Systems’ European gasoline Engine Management Systems Technical Director, Dr. Sebastian Schilling: “These are very high performance systems, but through careful optimization of the subsystems we have been able to avoid the need for expensive, novel technologies.”
He added that Delphi created each subsystem to accommodate flexibility in the engine architecture, giving the engine designer more freedom and allowing added carryover.
Developed at technical centers in Luxembourg and the U.S., the systems will meet the requirements of Euro6 with either homogeneous or stratified-charge combustion strategies.
The new range of GDi injectors are available as an inwardly opening multihole injector (Multec 12) for homogeneous combustion and as an outwardly opening injector (Multec 20) for stratified combustion. Both are operated by conventional solenoid technology.
Schilling said this provides significant weight advantages as well as lower unit cost. System cost in particular can be reduced, he said, due to the lower cost ECU required for solenoid-driven injectors.
For direct-injection applications, piezo-driven injectors have been gaining favor over solenoid-driven types due to their capability to deliver the closely spaced multiple-injection events with exact penetration, spray stability, and the very fine fuel atomization required. This is particularly true when applied to spray-guided stratified combustion.
According to Schilling, the Fast Single Coil (Multec 20) injectors deliver performance comparable to piezo types without the additional cost associated with their high-voltage driver circuits.
Both the Multec 12 and 20 injectors are designed for reduced NVH, which can help the vehicle manufacturer reduce the cost and weight of additional noise-reduction materials.
A similar engineering strategy has been applied to Delphi’s Multi-Charge Ignition that provides additional freedom in injector and spark plug positioning, which is crucial in deciding whether or not a cylinder head must be expensively re-engineered to meet new emissions requirements.
Spray-guided, stratified-charge combustion concepts have highly varying fuel mixture concentrations close to the spark plug. This requires very short time intervals between injection and ignition events, traditionally requiring the spark plug to be located near the injector.
Delphi's Multi-Charge Ignition system fires the spark plug multiple times per combustion event. This enhances the lean-burn process and allows engine designers to take full advantage of a stratified-combustion strategy without compromising combustion stability, Schilling noted. He said it offers a significant improvement in both emissions and fuel consumption as well as the potential to switch to smaller and lighter ignition coils.
To complement its range of GDi technologies, Delphi also is introducing other optimized subsystems. They include a high-efficiency fuel pump; an injector developed specially for compressed natural gas (CNG) that is compatible to a typical gasoline electronic control module; and a very high speed electric cam phaser.
The cam phaser features a broad operating span that can help improve starting. It is also aimed at supporting development of HCCI (Homogeneous Charge Compression Ignition) combustion strategies.