SUPERCHARGER WITH CONTINUOUSLY VARIABLE DRIVE SYSTEM
TECHNICAL FIELD
[001] The present disclosure relates generally to positive displacement air
pumps for supplying air to an engine. A control strategy utilizes a continuously variable
transmission in combination with a fixed capacity supercharger.
BACKGROUND
[002] In general, the amount of air provided to a combustion engine is
proportionally related to an amount of power that the engine can provide. The power can
be supplied as rotational shaft energy to a variety of devices, including vehicles such as
automobiles. The engine power is related to its output shaft rotations per minute (RPM)
and the torque that shaft is providing. In order to have varying output powers at a given
engine RPM, the output shaft torque must vary. The output shaft torque is a function of
many variables, but it is largely related to the amount of air entering the engine.
[003] An air boosting system allows the engine to consume more air, thus
resulting in the ability to make more torque at the output shaft. One such boosting
system is a supercharger, which is a positive displacement air pump that comprises
parallel lobed rotors. A supercharger may provide air or other gaseous matter to an
internal combustion engine.
[004] The supercharger may be combined with airflow valves to provide the
exact amount of air required to the engine. Because superchargers are generally designed
for a fixed volume of air, a bypass valve may also be included. The bypass valve is
opened when the full amount of air flowing through the supercharger is not required by

the engine. The excess air mass is then allowed to recirculate and enter the inlet of the
supercharger again. Any excess air being recirculated still requires energy to pump, and ,
thus decreases the overall efficiency of the boosting system.
[005] Prior art systems have used fixed pulley designs having a pulley attached-
to a rotating crank shaft of an engine and to a rotational shaft of a supercharger. As
engine RPMs increase, and thus the engine's demand for air, the fixed pulley allows the
supercharger's rotors to spin faster to provide additional air. The pulley typically sets a
fixed ratio between engine RPMs and the supercharger RPMs. While the fixed pulley
system allows for the advantage of varying air supply, the air supplied is not always the
optimal amount. In addition, the use of a fixed ratio results in a system where either the
engine or the supercharger or both cannot be used to the full extent of its rated
operational range, resulting in wasted capacity.
SUMMARY
[006] In one embodiment, a engine system may comprise a throttle valve
configured to variably open and close to selectively restrict a volume of air flow, a
supercharger comprising an air inlet, an air outlet, a rotatable drive shaft and rotors
associated with the drive shaft, a combustion engine comprising combustion chambers
and an associated rotatable crank shaft, and a continuously variable transmission (CVT)
configured to variably transfer rotational energy between the drive shaft and the crank
shaft. The supercharger may be sized to have a flow rate that substantially prevents
backwards leaking of air flow.
[007] The engine system may be configured such that the throttle valve is open,
the CVT transfers rotational energy from the crank shaft to the drive shaft such that the

drive shaft rotates more per minute than the crank shaft, and the supercharger supplies a
pressurized volume of air to the combustion engine.
[008] The engine system may be configured such that the throttle valve is open,
the CVT transfers rotational energy from the drive shaft to the crank shaft, the rotors
receive torque, and the supercharger has a negative pressure differential from the air inlet
to the air outlet.
[009] The engine system may also be configured such that the throttle valve is
partially closed, the CVT transfers rotational energy from the drive shaft to the crank
shaft, the rotors receive torque, and the supercharger has a negative pressure differential
from the air inlet to the air outlet.
[010] The engine system may also comprise an exhaust gas recirculation valve,
an air intake manifold, and an air exhaust manifold, wherein the air intake manifold
interposes the supercharger and the engine, the air exhaust manifold receives air from the
combustion engine, and the exhaust gas recirculation valve variably transmits air from
the air exhaust manifold to the air intake manifold.
[011] In another embodiment, an air transfer system may comprise a positive
displacement air pump comprising an air inlet, an air outlet, at least one rotor to move air
from the air inlet to the air outlet, and a drive shaft connected to the rotor to rotate the
rotor, a valve comprising a variably movable air restriction plate, an engine comprising
air combustion chambers and an associated crank shaft, and a CVT having means for
transmitting a variable amount of rotational energy. The continuously variable
transmission may be connected between the drive shaft and the crank shaft for
transmitting rotational energy.

[012] It is to be understood that both the foregoing general description and the
following detailed description are exemplary and explanatory only and are not restrictive
of the invention, as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[013] The accompanying drawings, which are incorporated in and constitute a
part of this specification, illustrate several embodiments of the invention and together
with the description, serve to explain the principles of the invention.
[014] FIG. 1 is an example of an ideal boosted torque curve and a prior art
torque curve.
[015] FIG. 2A is an example of an engine system with an open upstream throttle
valve and a boosted air supply.
[016] FIG. 2B is an example of an engine system with an open upstream throttle
valve and supercharger throttling.
[017] FIG. 2C is an example of an engine system with a partially closed
upstream throttle valve and supercharger throttling.
[018] FIG. 2D is an example of an engine system with an open upstream throttle
, valve and an open exhaust gas recirculation (EGR) valve.
[019] FIG. 3A is an example of an engine system with an open downstream
throttle and a boosted air supply.
[020] FIG. 3B is an example of an engine system with an open downstream
throttle valve and supercharger throttling.
[021] FIG. 3C is an example of an engine system with a partially closed
downstream throttle valve and supercharger throttling.

[022] FIG. 3D is an example of an engine system with an open downstream
throttle valve and an open EGR valve.
[023] FIG. 4 is a graph of operating speed for an example of a prior art fixed
pulley ratio system supercharger.
[024] FIG. 5 is a graph of operating speed for an example of a CVT and
supercharger arrangement.
[025] FIG. 6 is a graph showing an amount of air mass bypassed in the example
of the prior art fixed pulley ratio supercharger arrangement.
[026] FIG. 7 is a graph of inlet power for the example of the prior art fixed
pulley ratio supercharger arrangement.
[027] FIG. 8 is a graph of inlet power for the example of the CVT and
supercharger arrangement;
[028] FIG. 9 is a graph of power savings for the example of the CVT and
supercharger arrangement.
DETAILED DESCRIPTION
[029] Reference will now be made in detail to the present exemplary
embodiments, examples of which are illustrated in the accompanying drawings.
Wherever possible, the same reference numbers will be used throughout the drawings to
refer to the same or like parts. Throughout the drawings, a line with an arrow-head
denotes an air pathway.
[030] An example of a prior art air supply and engine system can include a
supercharger in fluid communication with an engine. The prior art supercharger may
comprise at least one lobed rotor and associated drive shaft for accelerating a volume of

air. The drive shaft may be associated with a fixed ratio pulley system. The fixed ratio
pulley system may comprise a first pulley connected to the drive shaft and a second
pulley associated with a crank shaft of the engine. A tension belt may be arranged on the
first pulley and the second pulley to allow the transfer of rotational power from the
engine crank shaft to the drive shaft. One example of a ratio of rotational power transfer
is 4:1, where every one turn of the engine crank shaft results in four turns of the drive
shaft. This allows the supercharger to increase the volume of air transferred by the rotor
each time the engine speed increases.
[031 ] Since the volume of air supplied to the engine directly affects the torque
output of the engine, the fixed ratio pulley system supplies a predictable volume of air to
the engine for a predictable increase in torque. Line E of Figure 1 shows the torque curve
for a prior art fixed pulley ratio supercharged engine. At low engine speeds, up to point
1, the transfer of energy from the engine to the supercharger is inadequate to spin the
rotor fast enough for an ideal amount of torque. The difference between the ideal torque,
shown on-line F, and the prior art torque is shown at D. Point 1 is, for many reasons, one
of the most critical points in an engine's operating range. It is the point at which a
vehicle has gone from an idled condition to a moving condition, and typically is a high
load condition.
[032] To achieve the ideal torque at point 1, the supercharger must provide more
air to the engine, but must not operate outside its capacity. With engine speed and
supercharger speed directly related by the use of a fixed pulley system, as engine speed
increases, the supercharger is at risk of overspeeding. Therefore, one cannot increase the
ratio between the pulleys too much to achieve a torque near ideal at point 1, since this

will cause an overspeed in the supercharger at later engine operating speeds. As a
compromise, the prior art designs typically accept a decrease in torque at point 1 so that
at a point 2, the system matches the ideal torque curve. Past this point, the supercharger
supplies too much air, but is within its operational speed. If the air were supplied to the
engine, it would cause an excessive amount of torque generation, shown at G. To avoid
the excess torque, the excess air is diverted by, for example, a bypass valve to prevent
oversupply of air to the combustion chamber of the engine. The bypass valve can allow
recirculation of air, or an outlet for air. In either scenario, a significant amount of energy
is wasted.
[033] To achieve the ideal boosted torque curve, applicant proposes the use of a
continuously variable transmission (CVT) in place of the fixed ratio pulley system. The
speed of the supercharger may be controlled so that the airflow output matches the
required flowrate of the engine. The variation in supercharger speed allows for more
customized variations in the torque output of an internal combustion engine. The CVT
may be used to control the speed of the supercharger "independent" of the engine RPM
and "dependant" on desired engine airflow under the commanded conditions.
[034] The CVT can be one of many types of devices allowing a rotational
difference between the engine crank shaft and the supercharger drive shaft. A
mechanical.type toroid, belt, planetary, or cone CVT allows for rotational energy transfer
from the crank shaft to the drive shaft. Or, the CVT can be electrical, such as an
independent electric motor.
[035] The CVT allows for a range of speeds on the drive shaft of the rotor. The
speeds can be greater than or less than the rotations per minute (RPMs) on the motor.

The CVT allows for a customizable air supply, and therefore, customizable torque output.
A high torque output is achievable at the low engine speeds of point 1, and an optimal
torque is achievable at point 2, At point 3, the supercharger can reach its peak airflow
substantially simultaneously to the engine reaching its peak power. For points above
point 3, the airflow can remain nearly constant. The engine output torque will decrease,
yet output power will remain largely the same. Instead of the significant power waste in
the area G, a power savings is achieved.
[036] An additional benefit is achieved by using a CVT: the fuel economy can
be increased more than 10% by engine downspeeding. The engine can be operated at
lower engine speeds, such as 1200 RPMs, which reduces engine friction. Ideally, the
engine will produce high torque at the low engine speed to maximize the downspeeding
benefits. Current designs have inadequate boost, or air supply, but a CVT design allows
the supercharger to supply air independent of engine speed, which increases boost at low
engine speed, which translates in to increased "low end torque." With more torque at low
engine speeds, longer transmission gear ratios can be used at low engine speed, resulting
in further increases in fuel economy.
[037] Yet another benefit to a supercharged engine can be achieved by using a
smaller size supercharger. Prior art designs select a supercharger size based upon the
airflow needed at point 2 of Figure 1. At rotational speeds greater than point 2,
supercharger efficiency is limited by internal sealing. At low rotational speeds, and thus
high pressure ratios, supercharger efficiency decreases because air is internally leaking
backwards, from outlet to inlet. By using a smaller supercharger to achieve the ideal

airflow, less backwards leaking of air occurs. The smaller supercharger must be operated
at higher rotational speeds to achieve the same airflow as a larger supercharger.
[038] A final benefit of using the smaller supercharger in combination with the
CVT is that the bypass valve can be eliminated. The CVT comprises a combination of
mechanisms that allow it to seamlessly switch along a range of effective gear ratios
between a minimum and maximum value. Therefore, the supercharger speed can be
varied such that the supercharger will provide only the exact air required by the engine.
The supercharger may be spun faster at low engine speeds to achieve high boost, and
spun slower at high engine speeds to prevent overspeeding.
[039] Controlling the CVT becomes a part of the vehicle electronics, and thus a
calibration strategy is required to determine the position, speed, and functionality of the
supercharger under all conditions. The calibration strategy may be implemented by, for
example, a computer having a processor, memory, algorithm stored in the memory, and
control electronics. The computer can also be used for controlling other devices, such as
an engine, a fuel injection system, throttling components, and exhaust gas recirculation
valves.
[040] The following example further illustrates the contrast between a fixed ratio
pulley design and a CVT design. A 2L engine with a maximum speed of 6500 RPM is
combined with a 0.57L supercharger with a maximum speed of 20,000 RPM. Example 1
includes a fixed pulley with a ratio of 4:1 to transfer energy from the engine to the
supercharger. Example 2 uses a CVT having a range of energy transmitting ratios.
[041] Table 1 (example 1) shows supercharger speed in RPMs for given
pressure ratios (vertical) and engine speeds in RPMs (horizontal). The supercharger

speed is linearly related to engine speed for the fixed ratio pulley example. When the
engine is at 5000 RPMs, the supercharger is slightly over its capacity. Past an engine
speed of 5500 RPMs, the supercharger is far past its limiting speed. Therefore, to protect
the supercharger, the engine cannot operate"past 5000 RPMs. This results in wasted
capacity, as the engine is not utilized along its full operational range. Also indicated by
the blank cells in Table 1, the fixed ratio pulley system cannot provide a range of
pressure ratios. That is, the system cannot provide high boost at low engine RPMs. The
results of Table 1 are also illustrated in Figure 4, which plots supercharger speed in
RPMs against the pressure ratio and engine speed in RPMs.


[042] Table 2 (example 2) shows that the CVT-driven supercharger speed is
controlled independent of engine speed (horizontal), and that a greater range of pressure
ratios (vertical) is achieved. The increased pressure ratio range allows for a greater range
of boost values. In addition, the supercharger may spin faster for high boost and low
engine RPMs and then spin slower for low boost and high engine RPMs. The results of
Table 2 are also illustrated in Figure 5, which plots supercharger speed in RPMs against
the pressure ratio and engine speed in RPMs


[043] Because the fixed pulley ratio supercharger of Table 1 is driven at a fixed
ratio, the limiting speed must be matched to the maximum engine speed. Therefore, it is
not achievable in the fixed pulley example to spin the engine above 5000 PRM without
damaging the supercharger.
[044] The same capacity supercharger in the CVT example of Table 2 has the
same limiting speed, yet the pulley ratio can change to allow the supercharger to operate
along its peak limiting speed over the operating range of the engine.
[045] Most traditional spark ignition internal combustion engines utilize an
airflow limiting feature such as a throttle valve in a throttle body to create a
subatmospheric pressure in the intake manifold. To create the subatmospheric pressure,
power is consumed.
[046] When using a CVT in combination with a supercharger, greater operating
freedom on the supercharger results in power savings. The rotors can be controlled to
force air towards the engine, or to restrict air to the engine. By slowing the rotors via the
CVT, therefore creating air restriction, subatmospheric inlet conditions can be created in

the intake manifold with less power consumption when compared to the prior art.
Slowing the rotors can be achieved via a change in the power transmission ratio of the
CVT, and, as discussed in more detail below, the resultant torque created on the rotors
can be supplied back the engine crank shaft for use in the system.
[047] With the CVT driven supercharger, the CVT can slow down the lobed
rotors enough to perform some or all of the necessary restriction previously provided by
the throttle valve. This creates a negative pressure differential across the supercharger.
The negative pressure differential will generate torque on the rotors. The drive system
and engine crank shaft must resist the torque, but in general, a portion of the torque
energy on the rotors is supplied back to the engine crank shaft. The torque transfer
results in an energy gain for the system.
[048] In addition to the power transfer benefits, the negative pressure differential.
is beneficial for such strategies as controlling manifold pressure to ensure adequate
Exhaust Gas Recirculation (EGR). That is, the negative pressure differential helps draw
air from the nearly atmospheric pressure exhaust stream, through an EGR valve, and back
in to the intake stream of the engine.
[049] Examples of torque energy transfer can be seen in Figures 2A-3D.
Figures 2D and 3D also illustrate EGR benefits. The examples include supercharger 201,
201', 201", 20r''' 301, 301', 301", and 301'", which is a positive displacement air
pump comprised of parallel lobed rotors. The air flow volume, air flow rate, and air flow
pressure can be controlled by selecting a supercharger of appropriate size and by
controlling the motion of the rotors. While specific atmospheric pressures and ratios are
shown in the examples, other values may be implemented by selecting one or more of a

rotor speed, CVT setting, throttle valve position, engine size, supercharger size, pulley
ratio, or engine speed. The system in each of Figures 2A-3D can achieve a range of
positive and negative pressure values, in addition to the singular values shown, therefore
allowing the system to operate under a wide range of load and environmental conditions.
For example, the system may yield substantial low end torque and operate in high altitude
areas.
[050] The examples of Figures 2A-3D use a 0.57L supercharger with a limiting
speed of 20,000 RPMs. CVT 206,206', 206", 206"', 301, 301', 301" and 301'"
controls the speed of rotation of associated supercharger rotors and can be any one of a
mechanical or electrical motor type, including, for example, toroidal, belt, planetary, and
conical. While a belt and pulley type CVT is illustrated in Figures 2A-3D, other energy
transferring or transmitting CVTs may also be used.
[051] Engine 203,203', 203", 203'", 303, 303', 303", and 303'" may be a
combustion type for an automobile, or other motive device, and may comprise 4, 6, 8, or
12 cylinders. An inner crank shaft connects to connecting rods, for actuation by pistons
associated with each cylinder. An oil sump, piston seals, and spark plugs are also
included. Each cylinder has at least one valve for exchanging air, but may also have
more valves, such as two air intake valves and two exhaust outlet valves. An intake
manifold system may be associated with the air intake valves to distribute air and can
comprise several air conduits, arranged in one example as one conduit for each air intake
valve, or the manifold system can comprise a single distribution body. In addition, the
exhaust outlet valves may have an associated exhaust manifold system comprising either
an exhaust outlet conduit for each exhaust outlet valve, or a single distribution body.

[052] Throttle valves 210,210% 210", 210"', 310,310', 310", and 310'" may
be any art-recognized throttling mechanism for selectively restricting a volume of air
flowing through a systqra, including, for-example, a passage-way with a rotatable
butterfly plate, or a passageway with a rotatable pass-through plate.
[053] Figure 2A illustrates an example of a relationship between a boosted state,
belt 209 tension, and pressure measurements PI, P2, P3, and P4. Open throttle valve 210
receives air of approximate ambient pressure, for example PI =~ 100 kPa. Throttle valve
210 may optionally adjust the air pressure to atmospheric pressure. Supercharger 201
then receives positive drive power via CVT 206 to spin the rotors thereby intaking ah' of
pressure P2 = 100 kPa and forcing it through the rotors and towards intercooler 202.
Supercharger 201 creates a higher pressure airflow at P3, which can be P3 = 200 kPa,
creating an effective pressure ratio of P3/P2 = 2.0.
[054] CVT 206 is operating at a high transfer ratio to transfer a high amount of
energy from engine 203 to supercharger 201. Belt 209, which traverses CVT pulley 207
and engine pulley 208, has a higher tension on an engine-pulling side than a tension on a
supercharger-pulling side. As shown in the example, Tl = 400 N and T2 =1000 N. That
is, supercharger 201 draws torque power from engine 203 to create high pressure air at
P3.
[055] Air from intercooler 202 enters combustion chamber of engine 203, where
it is used in the combustion process, and exits toward muffler 205. The exiting air is of
pressure P4 =~ 100 kPa plus pressure from exhaust restriction.
[056] Figure 2B illustrates an example having an engine throttle valve 210'
upstream from supercharger 201'. Engine throttle valve 210* is open. While no boosting

from supercharger 201' is needed, CVT 206' controls the speed of supercharger 201' so
that supercharger 201' provides all of the engine throttling function. Therefore,
supercharger 201' operates with negative drive power. That is, CVT 206' is a conduit to
provide torque energy back to a crank shaft of engine 203'. "CVT 206' operates with a
low ratio, meaning the energy transfer from the crank shaft to the supercharger is lower
than the energy transfer from the supercharger back to the crank shaft. Belt 209' assists
with the energy transfer through its tensioning. As shown in Figure 2B, belt 209' is
tensioned across CVT pulley 207' and engine pulley 208'. The supercharger-pulling side
of belt 209' has a tension Tl = 700 N, which is greater than tension T2 = 400 N on
engine-pulling side of belt 209'. That is, supercharger 201' provides torque power to
engine 203'.
[057] In the example of Figure 2B, a pressure drop occurs across supercharger
. 201. For example, air enters the system at ambient pressure, for example PI =~ 100 kPa.
Throttle valve 210'may optionally adjust the air pressure to atmospheric pressure. Air
then enters supercharger 201* at P2 = 100 kPa and exits at P3 = 80 kPa, for an effective
pressure ratio of P3/P2 = 0.8. The reduced pressure air is cooled in optional intercooler
202' and is provided to engine 203'. After use in the combustion chamber, spent air
enters optional muffler 205' at pressure P4 = 100 kPa plus additional pressure from
exhaust restriction.
[058] Figure 2C illustrates an example having engine throttling function from
both engine throttle valve 210" and supercharger 201". This combination creates a
pressure drop at P2, and a second pressure drop at P3.

[059] Engine throttle valve 210" is upstream from supercharger 201" and is
partially closed. While no boosting from supercharger 201" is needed, CVT 206"
controls the speed of supercharger 201" so that supercharger 201" provides a portion of
the engine throttling function.-The remainder of the throttling function is provided by
throttle valve 210". A computer system having a processor and a memory with a stored
control algorithm may assist with the extent of throttling provided by supercharger
201 "and throttle valve 210";
[060] Supercharger 201" operates with negative drive power. That is, CVT
206" is a conduit to provide torque energy back to a crank shaft of engine 203". CVT
206" operates with a low ratio, meaning the energy transfer from the crank shaft to the
supercharger is lower than the energy transfer from the supercharger back to the crank
shaft. Belt 209" is tensioned across CVT pulley 207" and engine pulley 208".
[061 ] In the example shown, the supercharger-pulling side of belt 209'' has a
tension Tl = 600 N, which is greater than tension T2 = 400 N on engine-pulling side of
belt 209". That is, supercharger 201" provides torque power to crank shaft of engine
203".
[062] Also shown in the example, air enters the system at ambient pressure, or
PI =~ 100 kPa. After being affected by throttle valve 210", air enters supercharger 201"
at P2 = 80 kPa and exits at P3 = 65 kPa, for an effective pressure ratio of P3/P2 = 0.8.
The reduced pressure air is cooled in optional intercooler 202" and is provided to engine
203". After use in the combustion chamber, spent air enters optional muffler 205" at
pressure P4 - 100 kPa plus additional pressure from exhaust restriction.

[063] Figure 2D is a final example having a throttle valve 210'" upstream from
supercharger 201"*. This example also includes an exhaust gas recirculation (EGR)
valve 211. CVT 206'" controls the speed of supercharger 201'" so that supercharger
-201"* provides all of the necessary engine throttling for this example. Engine throttle
valve 210"* is upstream from supercharger 201"* and is open. Supercharger 201'"
operates with negative drive power. That is, CVT 206*" is a conduit to provide torque
energy back to a crank shaft of engine 203'". CVT 206'" operates with a low ratio,
meaning the energy transfer from the crank shaft to the supercharger is lower than the
energy transfer from the supercharger back to the crank shaft. Belt 209'" is tensioned
across CVT pulley 207'" and engine pulley 208"'. In this example, the supercharger-
pulling side of belt 209'" has a tension Tl = 700 N, which is greater than tension T2 =
400 N on engine-pulling side of belt 209'". That is, supercharger 201'*' provides torque
power to crankshaft of engine 203'**.
[064] Air enters the system at ambient pressure PI =~ 100 kPa. Throttle valve
210'*' may optionally adjust the air pressure to atmospheric pressure. Air then enters
supercharger 201"' at P2 = 100 kPa and exits at P3 = 80 kPa, for an effective pressure
ratio of P3/P2 = 0.8. The reduced pressure air is cooled in optional intercooler 202'" and
is provided to engine 203"'. After use in the combustion chamber, used air exits towards
optional muffler 205'" at pressure P4 = 100 kPa plus additional pressure from exhaust
restriction. Some or all of the used air can either recirculate into the air stream entering
engine 203"* via exhaust gas recirculation (EGR) valve 211, or some or all of the used
air can exit the system through the muffler 205'".

[065] The EGR valve is useful for conditions when it is beneficial for exhaust
gas to enter the intake manifold of engine 203'". Intake manifold interposes intercooler
202"' and engine 203'". Since air flows due to pressure differences, the lower pressure
in the intake system encourages therdir to flow from the nearly atmospheric pressure
exhaust at P4 into the slightly below atmospheric pressure intake manifold.
[066] Figures 3A-3D show examples where a throttle valve is downstream from
a supercharger. Figure 3A shows air at ambient pressure P5=~ 100 kPa entering
supercharger 301. Supercharger 301 provides boosting, which increases the air pressure
above atmospheric, and air exits at pressure P6, for example P6 = 200 kPa. In this
example, the effective pressure ratio is P6/P5 = 2.0. The air then enters optional
intercooler 302 and is supplied to open throttle valve 310. Air exiting throttle valve 310
is also at pressure P7 = 200 kPa, and is used in combustion engine 303. Used air exits
engine 303 and enters optional muffler 304 at pressure P8 =~ 100 kPa plus additional
pressure from exhaust restriction.
[067] CVT 306 is operating at a high transfer ratio to transfer a high amount of
energy from crank shaft of engine 303 to a rotor drive shaft of supercharger 301. Belt
309, which traverses CVT pulley 307 and engine pulley 308, has a higher tension T4 oft
an engine-pulling side than a tension T3 on a supercharger-pulling side. For example, T4
=1000 N and T3 = 400 N. That is, supercharger 301 draws torque power from engine
303 to create high pressure air at P6.
[068] Figure 3B shows an example of supercharger 301' providing engine
throttling. The system does not require air boosting by supercharger 301', so CVT 306*
controls the speed of supercharger 301' so that supercharger 301' provides all of the

engine throttling function and so that the lobed rotors are slowed to create torque on the
rotors. This torque is supplied, via the low transfer ratio on CVT 306', to crank shaft of
engine 303'. Belt 309' spans CVT pulley 307' and engine pulley 308'. Tension T3 on a
supercharger-pulling side of belt 309' is greater than tension T4 on engine-pulling side of
belt 309'. In other words, the drive power of the supercharger 301' is negative. In the
example shown, T3 = 700 N and T4 = 400 N.
[069] Air at ambient pressure P5=~ 100 kPa enters supercharger 301 *.
Supercharger 301' has a negative pressure differential across it, and air exits at pressure
P6 = 80 kPa, for an effective pressure ratio of P6/P5 = 0.8. The air then enters optional
intercooler 302' and is supplied to open throttle valve 310'. Air exiting throttle valve
310' is at pressure P7 = 80kPa, and is used in combustion engine 303*. Used air exits
engine 303' and enters optional muffler 304' at pressure P8 =~ 100 kPa plus additional
pressure from exhaust restriction.
[070] Figure 3C illustrates an example of engine throttling by both supercharger
301" and throttle valve 310". Supercharger 301" does not provide all of the throttling
function. Therefore, throttle valve 310" is partially closed to supply a portion of the
throttling function for engine 303". A computer system having a processor and a
memory with a stored control algorithm may assist with the extent of throttling provided
by supercharger 301" and throttle valve 310".
[071] The system does not require air boosting by supercharger 301", so CVT
306" controls the speed of supercharger 301" so that supercharger 301" provides a
portion of the engine throttling function and so that the lobed rotors are slowed to create
torque on the rotors. The torque from the rotors is supplied, via the low transfer ratio on

CVT 306", to crank shaft of engine 303". Belt 309" spans CVT pulley 307" and
engine pulley 308". In this example, tension T3 = 700 N on a supercharger-pulling side
of belt 309" is greater than tension T4 = 400 N on engine-pulling side of belt 309". In
other words, the drive power of the supercharger 301" is negative,
[072] Air of pressure P5=~ 100 kPa enters supercharger 301". Supercharger
301" has a negative pressure differential across it, and air exits at pressure P6 = 80 kPa,
for an effective pressure ratio of P6/P5 = 0.8. The air then enters optional intercooler
302" and is supplied to partially closed throttle valve 310". Air exiting throttle valve
310" is at pressure P7 = 65 kPa, and is used in combustion engine 303". Used air exits
engine 303" and enters optional muffler 304" at a pressure P8 =~ 100 kPa plus
additional pressure from exhaust restriction.
[073] Figure 3D illustrates an example of a downstream throttle with exhaust
gas recirculation (EGR) where supercharger 301"' provides some or all of the throttling
via speed control from CVT 306"'. Supercharger 301'" operates with negative drive
power. That is, CVT 306"' is a conduit to provide torque energy back to a crank shaft of
engine 303'". CVT 306'" operates with a low ratio, meaning the energy transfer from
the crank shaft to the supercharger is lower than the energy transfer from the
supercharger back to the crank shaft. Belt 309'" is tensioned across CVT pulley 307'"
and engine pulley 308'". In this example, the supercharger-pulling side of belt 309'"
has a tension T3 - 700 N, which is greater than tension T4 - 400 N on engine-pulling
side of belt 309'". That is, supercharger 301'" provides torque power to crank shaft of
engine 303"'.

[074] Air enters supercharger 301''' at pressure P5 =~ 100 kPa. Air exits at P6
= 80 kPa, for an effective pressure ratio of P6/P5 - 0.8. The reduced pressure air is
cooled in optional intercooler 302'" and is provided to open throttle valve 310"' which
passes the air to engine 303"'. After use in the combustion chamber, used airexits
towards optional muffler 304'" at pressure P4 - 100 kPa plus additional pressure from
exhaust restriction. The some or all of the used air can either recirculate into the air
stream entering engine 303"' via exhaust gas recirculation (EGR) valve 311, or some or
all of the used air can exit the system through the muffler 304'".
[075] The EGR valve is useful for conditions when it is beneficial for exhaust
gas to enter the intake manifold of engine 303'". Intake manifold interposes intercooler
302"' and engine 303"'. Since air flows due to pressure differences, the lower pressure
in the intake system encourages the air to flow from the nearly atmospheric pressure
exhaust at P4 into the slightly below atmospheric pressure intake manifold.
[076] CVT 206,206', 206", 206'", 301,301', 301" and 301"' allows for
precise control of the rotor speed, and therefore, also allows for precise control of the
volume of air mass supplied for combustion. Because of the precise air mass control, no
bypass valve is needed in the examples of Figures 2A-3D. Eliminating the bypass valve
results in power savings for the example systems.
[077] Figure 6 illustrates the percent of air mass, bypassed in a prior art fixed
pulley ratio 0.57 L supercharger with a 2 L engine. The prior art system is designed for
optimal operation for only a portion of the operating range, which results in the intake of
excess air mass for the remainder of the operating range. At low engine RPMs and high
pressure ratio little or no air mass is bypassed. As the pressure ratio decreases and engine

speed increases, the percentage of total air mass volume bypassed using the bypass valve
increases. The bypassed air mass requires additional engine power to drive the prior art
supercharger, as shown in Figure 7.
[078] When using a CVT drive instead-of the fixed pulley ratio design, the
supercharger spins faster at low engine speeds to increase boost, and spins slower at
higher engine speeds to prevent overspeeding the supercharger. The engine power
required for the CVT driven supercharger is shown in Figure 8.
[079] Comparing Figures 7 and 8, the missing cells at the low engine speeds in
Figure 7 indicate that the prior art supercharger cannot provide a high pressure ratio for
the air mass intake. However, the CVT driven supercharger of Figure 8 can provide a
high pressure ratio for the air mass intake over the entire engine operating range,
[080] Figure 9 illustrates the input power saved by operating the supercharger
with a CVT drive instead of a fixed pulley ratio design. The input power savings with the
CVT drive is approximately 3-5 kW at 4000-4500 engine RPMs and 1-1.5 kW at 2000-
2500 RPMs under part load conditions. For a 2L engine, the power savings translates in
to an approximately 1-3% fuel economy gain at low to mid loads. The CVT driven
supercharger enables the combined benefits of higher pressure ratios at low engine speeds
(more "low end boost") and reduced supercharger input power.
[081 ] In the preceding specification, various preferred embodiments have been
described with reference to the accompanying drawings. It will, however, be evident that
various other modifications and changes may be made thereto, and additional
embodiments may be implemented, without departing from the broader scope of the
invention as set forth in the claims that follow. For example, other pressure values P1-P8

may be implemented to achieve other operating conditions. Also, belt tensions T1-T4
may be adjusted. The specification and drawings are accordingly to be regarded in an
illustrative rather than restrictive sense.
[082] Other embodiments of the invention will be apparent to those skilled in the
art from consideration of the specification and practice of the invention disclosed herein.
It is intended that the specification and examples be considered as exemplary only, with
the true scope and spirit of the invention being indicated by the following claims.

WE CLAIM:
1. An engine system, comprising:
a throttle valve configured to variably open and close to selectively restrict a
volume of air flow;
a supercharger comprising an air inlet, an air outlet, a rotatable drive shaft and
rotors associated with the drive shaft, wherein the supercharger is sized to have a flow
rate that substantially prevents backwards leaking of air flow;
a combustion engine comprising combustion chambers and an associated
rotatable crank shaft; and
a continuously variable transmission (CVT) configured to variably transfer
rotational energy between the drive shaft and the crank shaft.
2. The engine system of claim 1, wherein:
the throttle valve is open,
the CVT is configured to transfer rotational energy from the crank shaft to the
drive shaft such that the drive shaft rotates more per minute than the crank shaft; and
the supercharger is configured to supply a pressurized volume of air to the
combustion engine.
3. The engine system of claim 1, wherein:
the throttle valve is open,
the CVT is configured to transfer rotational energy from the drive shaft to the
crank shaft,

the rotors are configured to receive torque, and
the supercharger is configured to have a negative pressure differential from the air
inlet to the air outlet.
4. The engine system of claim 1, wherein:
the throttle valve is partially closed,
the CVT is configured to transfer rotational energy from the drive shaft to the
crank shaft,
the rotors are configured to receive torque, and
the supercharger is configured to have a negative pressure differential from the air
inlet to the air outlet.
5. The engine system of claim 1, further comprising an exhaust gas recirculation
valve, an air intake manifold, and an air exhaust manifold, wherein the air intake
manifold interposes the supercharger and the engine, the air exhaust manifold receives air
from the combustion engine, and the exhaust gas recirculation valve variably transmits
air from the air exhaust manifold to the air intake manifold.
6. The engine system of claim 1, wherein the supercharger interposes the engine and
the throttle valve.
7. The engine system of claim 1, wherein the throttle valve interposes the
supercharger and the engine.

8. The engine system of claim 1, wherein the CVT is one of an electric motor, a
toroidal type transmission, a belt and pulley type transmission, or a cone type
transmission.
9. The engine system of claim 1, wherein the CVT restricts the transfer of rotational
energy from the crank shaft to the drive shaft such that the rotors resist air passing
through the supercharger, thereby creating torque on the rotors.
10. The engine system of claim 9, wherein the torque is transferred to the drive shaft
and the CVT transfers the torque to the crank shaft.
11. An air transfer system comprising:
a positive displacement air pump comprising an air inlet, an air outlet, at least one
rotor to move air from the air inlet to the air outlet, and a drive shaft connected to the
rotor to rotate the rotor;
a valve comprising a variably movable air restriction plate;
an engine comprising air combustion chambers and an associated crank shaft; and
a continuously variable transmission (CVT) having means for transmitting a
variable amount of rotational energy,
wherein the CVT is connected between the drive shaft and the crank shaft for
transmitting rotational energy.
12. The air transfer system of claim 11, wherein the CVT controls the speed of
rotation of the drive shaft.

13. The air transfer system of claim 12, wherein the drive shaft rotates at greater
rotations per minute (RPM) than the crank shaft, thereby causing the rotors of the
positive displacement air pump to spin to provide pressurized air to the engine.
14. The air transfer system of claim 12, wherein the crank shaft rotates at greater
RPM than the drive shaft.
15. The air transfer system of claim 14, wherein the speed of rotation of the drive
shaft is slow enough to cause the rotors to resist air flow, thereby creating torque on the
rotors.
16. The air transfer system of claim 14, wherein the speed of rotation of the drive
shaft is slow enough to cause the rotors to resist air flow, thereby creating a negative
pressure differential across the positive displacement pump.
17. The air transfer system of claim 16, wherein the engine comprises an air intake
manifold associated with the air combustion chambers, and the negative pressure
differential creates a subatmospheric pressure in the air intake manifold.
18. The air transfer system of claim 17, further comprising:
an air exhaust manifold associated with the air combustion chambers; and
an exhaust gas recirculation valve for variably transmitting air from the air
exhaust manifold to the air intake manifold.