Inverted Function Turbocharger are used for air scavenging task in closed-loop system

As per the Boyle & Mariotte's
p1v1 = p2v2       (due to the fact
that the LTCev
is an unequal volume
closed-loop system)
operating mostly at constant
the pressure  conditions will
change as shown,
due to successive closures of
VVICC  valve
while the
IFT ( pump) is
as illustrated here

IFT:   Inverted-Function-Turbocharger   :
an emerging turbocharger derived North American technology
Turboscavenger  TM            

Canadian Patent CA 2,732,477        US  PATENT   8,683,987

IFT recuperates a fraction of the normally lost exhaust cycle's gas velocity's energy & pressure to reduce a VVICC's air pressure

NOTE: Substantially less Otto cycle exhaust-gas energy is required by the inverted-function-turbocharger" system to reduce closed-loop air pressure system of a cylinder's VVICC
than the energy required for open-loop air charging system configuration by a conventional turbocharger to raise a cylinder intake charge pressure;
this due to
IFT's "unequal volume closed-loop's configuration"   see below : IFT fig.2

Reducing VVICC's pressure is a mandatory condition for generating indirect pneumatic 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 releasing some or
all the atmospheric pressure force to assist Otto intake cycle pumping task and cost effectively emulate direct fuel injection system's no-pumping-loss ability to provide adequate intake-cycle-dynamic-pressure
Δp = O  in
spite of using a cost effective throttle, yet 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 to
generate pumping-gain when Delta P or  ∆p becomes less than  zero.
    In addition to relying on throttle-less advanced and technically advanced Direct Fuel Injection  ( the LTCev is not only compatible with direct fuel injection 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 have an exhaust gas driven turbine
    Both turbines are more effective at higher engine loads.
    For different reasons, both can advantageously be electrically assisted

      Task: to raise pressure of a high volume of air charge for admission into the cylinders
  • turbocharger air pressure charging work is only related to combustion process.
    The compressor's inertia factor is disadvantageous (generating turbo-lag)
    used in an open loop system

    The turbocharger's compressor charging task is intensive, (as it compresses a large volume of air into a
    significantly smaller volume) of a cylinder at a significantly higher pressure resulting in higher pressure ratio work.

    IFT     inverted-function-turbocharger
              IFT's limited task: to timely dynamically reduces the pressure of one small volume (dry sump cylinder's VVICC )
    during a cylinder 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 only successively and alternately creates a suitable under-pressure condition
    in a small enclosed cylinder's VVICC of a cylinder performing its intake cycle and let it
    expand in substantially much larger enclosed expansion volume (s). (as Boyle's & Mariotte's law)
    IFT is only  used in a closed loop system.

IFT inverted-function-turbochargers are used in uniquely adapted
    wet-sump/dry-sump crankcase configuration and ventilation system.
  •        IFT: inverted-function-turbocharger  provides a lightweight simple & affordable indirect-pneumatic-coupling mean  
            light turbo compound variant compatible to  both CAIC & UAIC strategy engine.
  •          IFT, air flow capacity required is quite low in spite of its high pressure ratio scavenging task because of the small air volume evacuated
    vs larger unequal expansion volumes, the IFT can still perform its task well,
    even at lower engine load than a normal turbocharger could.
Turbo lag is related to boost threshold of turbocharger but non-relevant for an IFT.

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 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 being evacuated
only generating minimal pressure increase level in the much larger volume 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 to increase as the
pumped VVICC volume is continually reducing through VVICC evacuation process and it repetitively operates only at momentary 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 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
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

  •        In spite of the fact that the LTCev may preferably be used as a "sustained-power" load Otto cycle engine; the possibility for addressing the
    widely variable loads and for slow moving and working utility vehicles, such as pick-up trucks
    or mild-hybrids assist, I.C.E vehicles and depending on the vehicle's intended use and applications; the
                IFT's configuration may optionally  be provided with variable vanes IFT or *may be electrically assisted.

    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, engine response and ample
    low end torque is immediate, and efficiency already increases 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."
hic inceptant futura
The  IFT :inverted function turbocharger compressor evacuates and reduces the pressure of a quite small limited
volume VVICC within a
closed-loop evacuation system and displaces said small limited air volume into  significantly
much larger total enclosed crankcase volumes of said closed-loop system of the engine while intentionally only  
minimally raising its pressure;
therefore requiring only a moderate charging pressure ratio from the IFT, that can
still be  available at lighter engine loads and
may be optionally electrically assisted for certain vehicle's unique for
frequent sustained  engine low load applications.
* NOTE  to reader
at bottom of index page
Jean-Pierre Marcil
Fig. 8
normal turbochargers are used for large volume air charging task in open-loop system
Inverted Function Turbochargers are used for low volume air scavenging task in closed-loop system
site copyright
R&DMI 03-21-2014
two one way valves # 59 prevent
back-pressure pressure surging
as an enclosed volume
(VVICC) gets near
full evacuation
unique IFT's pulsating
borders surging
near the
end of each intake cycles

p1v1 = p2v2       (due to the fact
that the LTCev
uses an unequal volume
closed-loop system)
operating mostly at constant
average temperature,
the pressure  conditions will
change as shown,
due to successive closures of
VVICC  valve
while the
IFT ( pump) is
as illustrated here