Delphi Multec 3.5 User Manual

Multec 3.5 Fuel Injector Application Manual System Interface
Delphi Energy and Chassis Systems
Revision: 11/05-1 4-15
Figure 4-9 - Electrical schematic of saturated switch injector driver circuit
4.4.5.1 Avalanche Energy
A magnetic field is generated by the injector coil when the injector is
turned on. This field breaks down when the injector is turned off inducing
voltage into the injector coil (much like an ignition coil). However,
instead of generating a spark, a voltage spike known as avalanche energy
is created which must be absorbed by the injector driver creating heat.
The energy the driver needs to dissipate when the inductive load is turned
off is one of the most important factors limiting driver life. The engine
controller must be configured to absorb or dissipate appropriate amounts
of avalanche energy.
Injector avalanche energy is typically evaluated at the minimum and
maximum operating temperatures and voltages. Typically, maximum
single event avalanche energy and repetitive avalanche energy values are
required for the controller. The avalanche energy for the Multec 3.5
injector is the same for all injector applications due to the common coil
design. (See section 3.15.2.)
The avalanche energy is calculated using an oscilloscope to measure the
voltage across and current through the driver during the injector shut-off
transient. These curves are multiplied together and integrated over time to
obtain the avalanche energy of the transient. (See Figure 4-10.)

Delphi Multec 3.5 Specifications

General

Brand	Delphi
Model	Multec 3.5
Category	Laboratory Equipment
Language	English