Jacobs Vehicle Systems has been leading the development of
engine braking technology for more than 50 years. In order to meet
the need for significantly increased vehicle retarding capability,
the company focused on the development of a High Power Density
(HPD) braking system.
Overall vehicle retarding requirements are continuously
increasing due to vehicle changes that improve fuel economy, such
as increases in aerodynamic efficiency and decreases in rolling
resistance, which in turn, reduce the vehicle's natural
retarding. This increase in overall vehicle retarding needs comes
at a time when the trend is to operate at lower engine RPM's
combined with downsizing of engine displacement to improve fuel
economy and reduce CO₂ emissions. The smaller displacement engine
will clearly produce less retarding power than the larger engine it
is replacing with standard engine braking technology.
In anticipation of this challenge, Jacobs Vehicle Systems has
developed an engine-integrated solution that will deliver
large-engine braking power in small- and medium-size engines, as
well as reduce the overall loading on the valve train during
braking.
The Jacobs' HPD brake provides for two-stroke engine braking
on a four-stroke diesel engine. This maximizes braking performance,
which results in an average increase of 104% in braking performance
over a conventional compression-release engine brake, particularly
at lower engine speeds where more than 200% gain in braking
performance was measured. By distributing the braking effort over
two events during the engine's full four-cycle process, the
valve train loads generated during braking are reduced by as much
as 30%.
