AKA: I. F. T.
IFT : Inverted-Function-Turbocharger : New patented Otto cycle gas-exchange facilitating technology
aka: "an unequal volume" closed-loop exhaust gas driven (positive-displacement (One -way-valve # 59) mainly turbo-scavenging & minimal pressure air
charging rotary pump provided by using an IFT that is minimum pressure blow-down turbine required mainly for simultaneously reducing air volume V1 P1 from an
Otto cycle multiple-cylinder engine's contracting VVICC (V1) during said Otto cylinder's intake-cycle and timely transfer said evacuated VVICC's V1 P1 air volume &
pressure into another expanding cylinder's VVICC (2) + other volumes 2* of said cylinder performing its exhaust-cycle larger combined volume
to advantageously allowing therefore to only minimally increase of said timely exhaust cycle cylinder'sVVICC V2 's pressure.
Canadian Patent CA 2,732,477 US PATENT 8,683,987
An Inverted Function Turbocharger's minimum-blow-down-power recovery turbine of a light turbo compound engine variant is used to recuperate
normally lost exhaust cycle's gas velocity's energy to drive the IFT's impeller that is used
to rarefy air pressure of an enclosed contracting cylinder's VVICCs' air volume (while said cylinder is performing its Otto intake cycle),
instead of charging air pressure into said cylinder as a conventional charging turbocharger.
Reducing VVICC's pressure is a mandatory condition for generating indirect pneumatic air-coupling.
The IFT is used for CAIC Otto cycle engine: reducing air Δp pressure within the small VVICC enclosed volume of a CAIC Otto cycle (throttled) S.I. engine, to allow
to generate indirect pneumatic coupling by allowing ambient air pressure in the cylinder provided by the available atmospheric pressure force to overcome the IFT's reduced air pressure induced into a
cylinder's VVICC of said cylinder performing its Otto Intake cycle to assist Otto intake cycle pumping task and cost effectively emulate UAIC direct fuel injection system's no-pumping-loss friction
ability to provide adequate advantageous intake-cycle-dynamic-pressure Δp = O in spite of using air-flow impiding cost effective throttle,
yet to prevent pumping-loss friction at part-load and provide the lowest GHG emission I.C.E engine, and being as efficient as cost effective as possible
as a suitable ICE component for reducing the inherently high cost of extended range electric hybrid vehicles; and
generating pumping-gain when Delta P or ∆p becomes less than zero.
but it can further enhance direct fuel injection's fuel efficiency superiority) by adequately injecting fuel directly into an uncontrolled-air intake-cycle,
in order to prevent pumping-loss friction so: Δp = O, The LTCev S.I. CAIC Otto cycle engine can simply relies and benefits from a non-obvious and robust
cost effective innovative turbo compound indirect pneumatic coupling mean to also neutralizes pumping-loss friction Δp = O by mean of technology
to enhance part-load fuel efficiency by providing "controlled-air intake-cycle" CAIC "throttled-engine" where pumping-losses friction Δp is either fractional
and less than zero in the cylinder performing intake-cycle 'at part-load by providing a matching under-pressure to the underside of the piston that is equivalent magnitude
level as the under-pressure timely exerted to the upper side of said piston; this is done in order to neutralize the dynamic pressure difference ΔP
and make it equal to zero , eliminating part-load pumping-loss friction. Beyond the condition where Δp exceeds zero level, further IFT optimization
can provide a lower under-pressure level and as Δp becomes above zero when the engine load increases further, even more beneficial pumping
assistance (or pumping-gain) due to Δp indirect pneumatic coupling turbo compound effect can be provided for even more fuel efficiency is provided.
turbocharger VS I.F.T. inverted-Function-Turbocharger
Both share general layout appearance and construction.
Both use an exhaust gas driven turbine
Both turbines are more effective at higher engine loads.
For different reasons, both can advantageously be electrically assisted
used in an open loop system
The turbocharger's compressor charging task is intensive, (as it compresses a substantially larger volume of air
into a significantly smaller cylinde's volume at a significantly higher pressure; this results in higher pressure ratio work.
IFT's limited task: to timely dynamically reduces the air pressure of one small volume (dry sump cylinder's VVICC's)
during a cylinder's Otto intake cycle and only bring it to ideal intake cycle Δp condition.
IFT's inertia can provide beneficial assistance to maintain turbo adequate rotational energy at low engine loads.
IFT's inertia assist controlling temporary surging, is advantageously used near the end of VVICC cycle
IFT's only pressure work is to successively and alternately creates a suitable air under-pressure condition
in a small enclosed cylinder's VVICC while said cylinder is performing its intake cycle and let air
expand into a substantially much larger enclosed expansion volume (s). (as Boyle's & Mariotte's law)
IFT are used in a closed loop system.
IFT inverted-function-turbochargers are used in uniquely adapted
The boost threshold of a turbocharger system relates to the minimum turbo RPM needed for the turbo to be physically capable to increase the air
pressure of an ambient volume from an unlimited amount of air of an open-loop system to increase an undetermined volume of air pressure with
required boost pressure above said ambient air pressure into a closed chamber.
Scavenging capacity threshold of IFT inverted function turbocharger is unrelated to turbo lag
The scavenging capacity threshold of inverted function turbocharger relates to the minimum turbo RPM needed for the inverted function turbocharger
to be physically capable to generate predetermined reduced Δp air pressure level difference between
two unequal volume closed chambers of a closed-loop system
while effectively generating useful under-pressure condition in the smaller volume chamber (VVICC) being evacuated
while only generating minimal pressure increase level in the much larger volume (VVICC)'s expansion chamber.
In general, due to the much larger displaced air volume involved, the boost threshold of a turbocharger occurs at a higher RPM than the RPM where
the scavenging threshold capacity of an inverted function turbocharger threshold occurs. The inverted function turbocharger indeed also benefits
from the reduced pumping load by allowing the inverted function turbocharger rotating speed momentum to be maintained as the
pumped VVICC air volume is continually reducing through VVICC evacuation process and it repetitively operates momentary at near surging condition
of each VVICC evacuation cycle due to Otto contracting VVICC volume cycles compressor successively increases speed temporarily to higher RPM
at the end of the VVICC scavenging cycle as it operates in a positive displacement pulsating mode in a rarefied atmosphere of the VVICC at near surging conditions.
The light turbo compound engine variant is a new turbo compound Otto cycle engine whose supplemental energy source provided to the engine is supplied by an ”indirect pneumatic coupling” process resulting from
conveniently exploiting timely existing pneumatic pressure level differences exerted separately onto each opposing faces of the piston performing its Otto intake cycle. Actual pneumatic assistance coupling is conveniently
provided by available ambient atmospheric pressure energy potential allowed and capable* of exerting more absolute pressure onto the working face of said piston conjointly with the provided timely reduced ambient
pressure level exerted onto the piston under-face facing VVICC of a cylinder performing its intake cycle. Said timely ambient VVICC under-pressure being provided by an inverted function turbocharger or I.F.T. Said I.F.T. is
used to reduce the ambient pressure onto the under face of the piston to provides Otto Intake cycle pneumatic pumping assistance resulting from unique indirect pneumatic coupling generated by the available atmospheric
pressure potential energy instead of prior-art heavier and more complex
direct mechanical or electrical coupling.
Indirect pneumatic coupling can be achieved when the available ambient atmospheric air pressure energy level can selectively and
timely be allowed to expose a piston’s crown of a piston performing its Otto intake cycle to a significantly higher pneumatic pressure
than the supplied pneumatic under-pressure provided by the IFT (inverted function turbocharger) in a VVICC of a cylinder performing
its Otto intake cycle.
UAIC strategy Otto cycle ( GDI S.I. & C.I engines) are capable* of providing the highest level of pumping-gain throughout the
engine load range while CAIC strategy engine are only capable*to produce pumping-gain at higher engine load range
the IFT's configuration can be benefit from optional with variable vanes or benefit from coming 42 volts electrical assistance.
Idle-stop technology should be advantageously used for CAIC strategy engine instead of sustained idling,
as the efficiency gain of the an non-electrically assisted IFT is virtually inexistant during idling mode; although than that,
once operated at part-load, the engine response and ample low end torque is immediate, and fuel efficiency ready increases
immediately from moderate engine load.
NOTE: " most electric hybrid vehicles propulsion system does not require any contribution from the Otto ICE component operation for low power and low speed operations."
NOTE: pending optimisation development
LTCev's unique "VVICC air / stray-oil" separation control" minimizes VVICC's stray-oil migration intimate contact into IFT's impeller that can
negatively affect IFT's operation's efficiency due to intimate mixing of blow-by water vapours that results from negatively affecting blending and accelerating engine oil and increasing its contamination as well as
increasing workload on PCV system Positive Crankcase Ventilation 's operation.
normal turbocharger are used for intake cycle air charging task in a open-loop system
As per the Boyle & Mariotte's
p1v1 = p2v2 (due to the fact
that the LTCev
is an unequal volume
erating mostly at constant
the pressure conditions will
change as shown,
due to successive closures of
while the IFT ( pump) is
as illustrated here
hic inceptant futura
|reed-valve # 59 (check-valve)
fitted before & after pump
|see larger version of fig.2 at the very
bottom of this page
|Note: Positive Displacement one-way valves reed-valves
are used to prevent detrimental air reversal flow as well as
pulsations occurrences from the IFT
|Inverted Function Turbocharger