(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)(19) World Intellectual Property Organization
International Bureau

11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111(10) International Publication Number(43) International Publication Date

22 September 2011 (22.09.2011)

PCT(51) International Patent Classification:
F02B 33122 (2006.01)(21) International Application Number:
PCT/US20ll/028284(22) International Filing Date:
14 March 2011 (14.03.2011)

WO 2011/115872 A1West Sussex BN43 6WL (GB). GILBERT, Ian; 67
Beach Green, Shoreham-by-Sea, West Sussex BN43 5YE(GB).
(74) Agents: FILDES, Christopher, J. et al.; Fildes & Outland, P.C., 20916 Mark Avenue, Suite 2, Grosse Pointe
Woods, MI 48236 (US).

(81) Designated States (unless otherwise indicated, for every
kind of national protection available): AE, AG, AL, AM,
AO, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ,
English(26) Publication Language:
CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO,(30) Priority Data:
DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT,
15 March 2010 (15.03.2010)
61/313,831
us
HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP,
61/363,825
13 July2010 (13.07.2010)
us
KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD,
18 July2010 (18.07.2010)61/365,343
us
ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI,NO,
NZ, OM, PE, PG, PH, PL, PT, RO, RS, RU, SC, SD,(71) Applicant (for all designated States except US): SCUDSE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR,
ERI GROUP, LLC [US/US]; 1111 Elm Street, Suite 33,
TT, TZ, VA, UG, US, UZ, VC, VN, ZA, ZM, ZW.
West Springfield, MA 01089 (US).
(25) Filing Language:

English(72) Inventors: MELDOLESI, Riccardo; 55 New Road,

Shoreham-by-Sea, West Sussex BN43 6RB (GB).
BADAIN, Nicholas; 37 Rosslyn Road, Shoreham-by-Sea,(8 4) Designated States (unless otherwise indicated, for every
kind of regional protection available): ARIPO (BW, GH,
GM, KE, LR, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG,
ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ,-- ------------------------------------------------------------------------------------------- FIG. 1[Continued on next page](54) Title: SPLIT -CYCLE AIR-HYBRID ENGINE WITH EXPANDER DEACTIVATION(57) Abstract: A split-cycle air-hybrid engine includes a rotatablecrankshaft. A compression piston is slidably received within a compression cylinder and operatively connected to the crankshaft. An expansion
piston is slidably received within an expansion cylinder and operatively
connected to the crankshaft. An exhaust valve selectively controls gas
flow out of the expansion cylinder. A crossover passage interconnects
the compression and expansion cylinders. The crossover passage includes a crossover compression (XovrC) valve and a crossover expansion (XovrE) valve therein. An air reservoir is operatively connected tothe crossover passage. An air reservoir valve selectively controls air flow
into and out of the air reservoir. In an Air Compressor (AC) mode of theengine, the XovrE valve is kept closed during an entire rotation of the
crankshaft, and the exhaust valve is kept open for at least 240 CA degrees of the same rotation of the crankshaft.

--;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

12

W 0 2011/11587 2 A 1 11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK,
EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU,
LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK,
SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ,
GW, ML, MR, NE, SN, TD, TG).

Published:with international search report (Art. 21 (3))

wo 2011/115872

PCT/US2011/028284

SPLIT-CYCLE AIR-HYBRID ENGINE WITH EXPANDER DEACTIVATIONTECHNICAL FIELD

This invention relates to split-cycle engines and,more particularly,S

to such an engine incorporating an air-hybrid system.

BACKGROUND OF THE INVENTION

For
10engine"aspurposes

used

in

of

the

clarity,present

theterm"conventional

applicationreferstoaninternal combustion engine wherein all four strokes of thewell- known

Otto

cycle

compression,

expansion(i.e.,

the(or power)

intake(orinlet) ,and exhaust strokes)

arecontained in each piston/cylinder combination of the engine.
15

Each stroke requires one half revolution of the crankshaft(180 degrees crank angle
the crankshaft(CA)),and two full revolutions of(720 degrees CA) are required to complete theentire Otto cycle in each cylinder of a conventional engine.
Also,
20

for

purposesofclarity,thefollowing

definition is offered for the term "split-cycle engine" as
may be applied to engines disclosed in the prior art and as
referred to in the present application.
A

split-cycle

engineasreferredtohereincomprises:25

a crankshaft rotatable about a crankshaft axis;acompression
crankshaft

compression
cylinder
such

that

pistonslidablyreceived

withinandoperatively

connected

tothecompression

pistonathe

reciprocatesthrough an intake stroke and a compression stroke during a30

single rotation of the crankshaft;wo 2011/115872

PCT/US2011/028284

2anwithinexpansionan expansion(power)cylinderpistonslidablyreceived

and operatively connected tothe crankshaft such that the expansion piston reciprocatesthrough an expansion stroke and an exhaust stroke during a5single rotation of the crankshaft; andacrossoverpassage(port)

compression and expansion cylinders,
including

at

least

a

crossoverinterconnecting

thethe crossover passage

expansion(XovrE)

valve

disposed therein, but more preferably including a crossover
10compression(XovrC)valve and a crossover expansion(XovrE)valve defining a pressure chamber therebetween.
United States
8,6,543,225 granted April

2003 to Scuderi and United States

granted October 11,
15

Patent No.

Patent No.

2005 to Branyon et al.,are incorporated herein by reference,
discussion
addition,ofsplit-cycle

and6, 952,923

both of whichcontain an extensive

similar-type

engines.

In

these patents disclose details of prior versionsof an engine of which the present disclosure details further
developments.
20

Split-cycle
cycle

enginewithanair-hybrid
airengines

reservoir

combineand variousasplit-

controls.

This combination enables a split-cycle air-hybrid engine to
store

energyreservoir.
25

in

the

form

of

compressed

air

in

the

air

The compressed air in the air reservoir is later

used in the expansion cylinder to power the crankshaft.
A split-cycle

air-hybrid

engineasreferredtoherein comprises:
a crankshaft rotatable about a crankshaft axis;
a30

compression
crankshaft

compression
cylinder
such

that

pistonslidablyandoperatively

thecompression

received withinconnected

pistontoathe

reciprocatesthrough an intake stroke and a compression stroke during asingle rotation of the crankshaft;wo 2011/115872

PCT/US2011/028284

3anwithinexpansionan expansion(power)cylinderpistonslidablyreceived

and operatively connected tothe crankshaft such that the expansion piston reciprocatesthrough an expansion stroke and an exhaust stroke during a5single rotation of the crankshaft;acrossoverpassage(port)

compression and expansion cylinders,
including

at

least

a

crossoverinterconnecting

thethe crossover passage

expansion(XovrE)

valve

disposed therein, but more preferably including a crossover
10compression(XovrC)valve and a crossover expansion(XovrE)valve defining a pressure chamber therebetween; andancrossoverairreservoir

passageandoperatively

selectively

connected

operable

to

to

the
store

compressed air from the compression cylinder and to deliver
15

compressed air to the expansion cylinder.
United States
8,

20

Patent No.

2 0 0 8 to Scuderi et al.,7,353,786 granted April

which is incorporated herein byreference,contains an extensive discussion of split-cycle

air-hybrid

andsimilar-type

patent discloses details

engines.

In

addition,of prior hybrid systems

thisof whichthe present disclosure details further developments.
A split-cycle air-hybrid engine can benormal operating or firing
the25

Enginemodes.

Firing(EF)

In the EF mode,

mode)

reservoir.

connecting

mode
and

(also commonly called
four

basic

air-hybrid

operating without the use of its

In the EF mode,

the

in a

the engine functions as a non-air

hybrid split-cycle engine,
air

(NF)

run

crossoverpassageatank valve operatively
to

the

air

reservoir

remains closed to isolate the air reservoir from the basic
30

split-cycle engine.
The

split-cycle

air-hybrid

engineoperates

the use of its air reservoir in four hybrid modes.
hybrid modes are:with

The fourwo 2011/115872

PCT/US2011/028284

4

Air

1)

Expandercompressed

(AE)

air

mode,

energy

which

from

includes

the

air

using

reservoir

without combustion;
2)
5

Air Compressor(AC)compressedenergyairmode,which includes

into

the

air

storing

reservoir

without combustion;
3)

Air Expander and Firing (AEF) mode, which includes
using compressed air energy from the air reservoir
with combustion; and10

4)Firingandstoring

Charging

compressed

(FC)
air

mode,

which

includesenergy

into

the

air

AE,

AC,

reservoir with combustion.
However,further

AEF and FC,
15

optimization of these modes,EF,

is desirable to enhance efficiency and reduce

emissions.

SUMMARY OF THE INVENTION

The present invention provides a split-cycle air20

hybrid engine in which the use of the Air Compressor(AC)mode is optimized for potentially any vehicle in any drive
cycle for improved efficiency.
Moreparticularly,

anexemplaryembodimentofasplit-cycle air-hybrid engine in accordance with the present
25

invention includes a crankshaft rotatable about a crankshaft
axis.

A compression piston iscompression
crankshaft

cylinder
such

that

slidably received within aandoperatively

thecompression

connected
pistontothereciprocatesthrough an intake stroke and a compression stroke during a30

single rotation of the crankshaft.
slidablyreceived

operatively
expansion

withinconnected

pistonto

An expansion piston isanexpansionthecrankshaft

reciprocatesthroughancylinder
such

that

expansionandthestrokewo 2011/115872

PCT/US2011/028284

5

and

an

exhaustcrankshaft.
outofstrokeduringasinglerotationoftheAn exhaust valve selectively controls gas flowtheexpansion

cylinder.

Acrossoverpassageinterconnects the compression and expansion cylinders.
5crossover passage includes a crossover compression
valve

and

pressure10

acrossoverchamber

expansion(XovrE)

therebetween.

operatively

connected

selectively

operable

to
to

An

cylinder.

An

air

the

crossoverstore

compressed

compression cylinder and to deliver
expansion

valve

air

The

(XovrC)

defining

reservoirispassage

and

from

the

compressed air tothereservoir

air

valve

selectively

controls air flow into and out of the air reservoir.
engine is operable in an Air Compressor
AC
15

mode,

the

XovrE

valve

is

rotation of the crankshaft,

kept

a

(AC)

closedThe

mode.

In theforentirean

and the exhaust valve is

kept

open for at least 240 CA degrees of the same rotation of the
crankshaft.
A methodofoperatingengine is also disclosed.
20asplit-cycle

air-hybrid

The split-cycle air-hybrid engine

includes a crankshaft rotatable about a crankshaft axis.

A

compression piston is slidably received within a compression
cylinderand operatively connected tothecrankshaft

suchthat the compression piston reciprocates through an intake
stroke and a compression stroke during a single rotation of25

thecrankshaft.

withinAn expansion piston isan expansion

cylinderslidably received

and operatively connected tothe crankshaft such that the expansion piston reciprocatesthrough an expansion stroke and an exhaust stroke during asingle30

rotationofthecrankshaft.

An

exhaustvalve

selectively controls gas flow out of the expansion cylinder.
A

crossoverpassageinterconnects

expansion

cylinders.

The

crossovercompression(XovrC)thecrossovervalve

compression

passageandincludesaandacrossoverwo 2011/115872

PCT/US2011/028284

6
expansion(XovrE)valve

definingapressurechamber

therebetween.

An air reservoir is operatively connected tothepassagecrossoverandselectively

operable

to

store

compressed air from the compression cylinder and to deliver5

compressed air to the expansion cylinder.

An air reservoir

valve selectively controls air flow into and out of the air
reservoir.
mode.

(AC)

The method in accordance with the present invention

includes10

The engine is operable in an Air Compressor

thefollowing

steps:

keeping

the

XovrE

valve

closed for an entire rotation of the crankshaft; and keeping
the exhaust valve open for at least 240 CA degrees of thesamerotationofthecrankshaft,wherebytheexpansion

cylinder is deactivated to reduce pumping work performed by
the expansion piston on air in the expansion cylinder.
15

These
invention will

and

other

be morefeaturesandadvantages

fully understood from the

of

the

followingdetailed description of the invention taken together with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS20

In the drawings:
FIG.

1 is a lateral sectional view of an exemplary

split-cycle air-hybrid engine in accordance with the present
25

invention; andFIG. 2 is a graphical illustration of pumping load(in terms of negative IMEP) versus engine speed in accordancewith the present invention.

30

DETAILED DESCRIPTION OF THE INVENTION

The following glossary of acronyms and definitionsof terms used herein is provided for reference.

wo 2011/115872

PCT/US2011/028284

7
In General
Unless otherwise specified,closing timings

all valve opening andare measured in crank angle

degrees

after

top dead center of the expansion piston (ATDCe) .
Unless5otherwise

are in crank angle degrees
Air tank

specified,

all

valve

durations(CA) .

(or air storage tank):

Storage tank for compressed

air.
ATDCe: After top dead center of the expansion piston.
10

15

Bar: Unit of pressure, 1 bar = 10 5 N/m 2
BMEP:

Brake

referstotheoutputas

outputshaft),

after

frictionfor.

Brake Mean Effective Pressure

effective

pressure.

deliveredThe

tolossesthetermcrankshaft(FMEP)(BMEP)"Brake"are(oraccounted

is the engine's

brake torque output expressed in terms of a mean effective
pressure

20

mean

(MEP)

value.

BMEP

isdivided by engine

displacement.

parameter

after

taken

the

equal

to

This
lossesbrake

torqueistheperformance

due

to

friction.

Accordingly,

BMEP=IMEP-friction.

Friction,

usually also

expressed in

of

terms

the

in this case isan MEP value

known

as

Frictional Mean Effective Pressure (or FMEP)
Compressor:

The

compression

cylinderandits

associatedcompression piston of a split-cycle engine.
Exhaust25(or EXH) valve: Valve controlling outlet of gas fromthe expander cylinder.
Expander:The

expansion

cylinderandits

associatedexpansion piston of a split-cycle engine.
FMEP: Frictional Mean Effective Pressure.
IMEP:
30

Indicated

Mean

Effective

Pressure.

The

term

"Indicated" refers to the output as delivered to the top of
the piston, before friction losses(FMEP) are accounted for.

Inlet

Also commonly referred to(or intake) :as the intake valve.

Inlet valve.

wo 2011/115872

PCT/US2011/028284

8

Inlet

air

(or

intakeair):cylinder on an intake
Inlet valve

Air drawn(or inlet)

into

the

compression

stroke.

(or intake valve):

Valve controlling intake ofgas into the compressor cylinder.
5

Pumping work (or pumping loss): For purposes herein, pumping
work(often expressed as negative IMEP)

relates to that partof engine power which is expended on thefuel

and air

chargeinto

theengineRatio

during(a/b)

ofinduction of theand theexpulsionofcombustion gases.
10

ResidualCompression

deactivation:

The ratio(a)expansion

cylinderthe trapped volume inthe expansion cylinder at the position just when the exhaust
valvecloses

to

(b)

the

trappedvolumeintheexpansion

cylinder just as the expansion piston reaches its top dead15

center position (i.e., the clearance volume).
RPM: Revolutions Per Minute.
Tankvalve:

Valve

connecting

the

Xovr

passagewith

thecompressed air storage tank.
VVA:
20

Variable

operable

to

valve

alter

actuation.

A

shape

timingtheormechanism
of

a

or

methodvalve's

lift

profile.
Xovr(orXover)

valve,

passage

or

port:

The

crossovervalves, passages, and/or ports which connect the compression
and25

expansion

cylindersthrough

which

gas

flows

from

compression to expansion cylinder.
XovrE(or XoverE)

valves: Valves at the expander end of thecrossover (Xovr) passage.
XovrE-clsd-Exh-open:

XovrE

valve

fully

closedandExhaust

XovrE

valve

fully

closedandExhaustopen

andExhaustvalve fully open.
30

XovrE-clsd-Exh-std:

valve having standard timing.
XovrE-open-Exh-clsd:
valve fully closed.

XovrE

valve

fully

wo 2011/115872

PCT/US2011/028284

9

XovrE-open-Exh-std: XovrE valve fully open and Exhaust valve
having standard timing.
XovrE-std-Exh-std:

XovrE

valve

havingstandard

timingandExhaust valve having standard timing.
5

Referring to FIG. 1, an exemplary split-cycle airhybrid engine is shown generally by numeral 10.

The split-

cycle air-hybrid engine 10 replaces two adjacent cylindersofaconventional

enginewithacombinationofcompression cylinder 12 and one expansion cylinder 14.
10

one
A

cylinder head 33 is typically disposed over an open end of
the expansion and compression cylinders 12,

14 to cover andseal the cylinders.
The

four

strokes

of

the

Otto

cycle

are

"split"over the two cylinders 12 and 14 such that the compression
15cylinder 12, together with its associated compression piston
20,

20

performtheintakeandpistonstrokes.

The Otto cycle is therefore completed in these twocylinders

12,

once

per

the

its

the

expansion

performwithandcylinder30,

togetherstrokes,

expansion

14

14,

compression

expansion

crankshaft

16

associatedandexhaustrevolution( 3 60degrees CA) about crankshaft axis 17.
During the intake stroke, intake air is drawn into
thecompression

disposed
25

in

the

cylinder12throughcylinder

head

33.

an

intake

port

19

An

inwardly

opening(opening inwardly into the cylinder and toward the piston)poppet intake valve 18 controls fluid communication between
the intake port 19 and the compression cylinder 12.
During30

piston20

chargeinto

thepressurizes
thecompression
the

air

stroke,chargecrossover passage

and

the

drives(or port)

typically disposed in the cylinder head 33.

compression

22,

the

air

which

is

This means thatthe compression cylinder 12 and compression piston 20 are asourceofhigh-pressure

gas

to

the

crossoverpassage22,

wo 2011/115872

PCT/US2011/028284

10which acts as the intake passage for the expansion cylinder
14.

In some embodiments,

two or more crossover passages 22

interconnect the compression cylinder 12 and the expansion
cylinder 14.
The geometric (or volumetric) compression ratio of5

thecompression cylinder 12of split-cycle engine

10

for

split-cycle

general)commonlyreferred toengine.
10asenginesinisthe "compression ratio"

The geometric(or volumetric)

hereinof thesplit-cycle

compression ratio of

the expansion cylinder 14 of split-cycle engine 10
split-cycle engines in general)(and(and foris herein commonly referred

to as the "expansion ratio" of the split-cycle engine.

The

geometric compression ratio of a cylinder is well known in
the art as the ratio of the enclosed (or trapped) volume in15

thecylinderreciprocating

20(including
therein

is

all
at

recesses)

its

when

bottom deadapistoncenter(BDC)

position to the enclosed volume(i.e.,

clearance volume)thecylinder when

said piston

is

at

its

(TDC)

position.

Specificallyfor

split-cycle

definedherein,thecompression

ratio

top

of

dead

centerenginesainascompression

cylinder is determined when the XovrC valve is closed.

Also

specifically for split-cycle engines as defined herein,

theexpansion ratio of an expansion cylinder is determined when
the XovrE valve is closed.
25

Due to very high compression ratios
1,

30

to

1,

40

to

cylinder12,anoutwardly opening

30

from

the

cylinder)

valve

24

at

the

flow

from

controlcrossover passage(e.g.,

20 to 1,

1,

or greater)

poppetcrossoverthe22.

passage

30 to 1,

40

to

the

compression

compression
inlet(XovrC)

25

is

used

to

cylinder

12

into

the

very high expansion

to 1,

20 to

(opening outwardly away

crossovercompression
Duewithin(e.g.,or greater)

ratioswithin the

expansion cylinder 14, an outwardly opening poppet crossoverwo 2011/115872

PCT/US2011/028284

11

expansion (XovrE) valve 26 at the outlet 27 of the crossover
passage 22 controls flow from the crossover passage 22 into
the expansion cylinder 14.

The actuation rates and phasingof the XovrC and XovrE valves 24,
5

thecrossover

26 are timed to maintainpressureinpassage

22

at

a

high

minimumpressure(typically 20 bar or higher at full

load)

duringall four strokes of the Otto cycle.
Atleast onefuelinjector 2 8 injects

fuel

into

the pressurized air at the exit end of the crossover passage
10

22 in correspondence with the XovrE valve 26 opening, which
occursshortly before expansion piston 30

deadcenterposition.

The

air/fuel

reacheschargeits

topenterstheexpansion cylinder 14 when expansion piston 30 is close to
its
15

top

dead

centerposition.

descent

fromits

dead center position,

top

XovrE valve 26 is still open,aspark plug

tip

39

that

As

piston30

beginsits

and whilethespark plug 32, which includes

protrudes

intocylinder14,isfired to initiate combustion in the region around the spark
plug
20

tip

39.

Combustion

can

be

initiated

while

the

expansion piston is between 1 and 30 degrees CA past its top
dead center (TDC) position.

More preferably, combustion canbe initiated while the expansion piston is between 5 and 25
degrees CA past its top dead center
preferably,
25

(TDC)

initiatedsuchasposition.

Most

combustion can be initiated while the expansion

piston is between 10
center(TDC)

position.

throughwithand 20CA past its

Additionally,

other

glow

degrees

ignitionplugs,

combustion

devicesmicrowave

and/or

top deadmaybemethods,

ignitiondevicesor

exhaust

gases

are

through compression ignition methods.
30

Duringtheexhauststroke,pumped out of the expansion cylinder 14 through exhaust port
35 disposed in cylinder head 33.
exhaust valve 34,

An inwardly opening poppet

disposed in the inlet 31 of the exhaust

wo 2011/115872

PCT/US2011/028284

12

port 35,

controls fluid communication between the expansion

cylinder 14 and the exhaust port 35.
and

the

exhaustpassage 22.
5

port

35

are

The exhaust valve 34

separate

from

the

crossoverThat is, exhaust valve 34 and the exhaust port

35 do not make contact with,or are not disposed in,thecrossover passage 22.
With the split-cycle engine concept, the geometricengineparameters

length,10(i.e.,

volumetriccompression

12

and

bore,

stroke,connecting

rodcompression

ratio,

etc.)

the

expansion

14cylindersofaregenerally

independent from one another.

For example, the crank throws

36,

cylinder38forcylinder 14,

thecompression

12

and

expansionrespectively, may have different radii and may

be phased apart from one another such that top dead center
15

(TDC)

of the expansion piston 30 occurs prior to TDC of thecompression piston 20.
cycle

engine10

toThis independence enables the split-

potentiallyachievehigherefficiency

levels and greater torques than typical four-stroke engines.
The geometric independence of engine parameters in20

the split-cycle engine 10 is also one of the main reasons
why pressure can be maintained in the crossover passage 22
as discussed earlier.
reaches

its

topSpecifically, the expansion piston 30

deadcenterposition

prior

to

the

compression piston reaching its top dead center position by25

a discreet phase angle(typically between 10 and 30

crank

angle

phase

properdegrees).

This

angle,

togetherwithtiming of the XovrC valve 24 and the XovrE valve 26, enables
thesplit-cycle

engine10

tomaintainpressurecrossover passage 22 at a high minimum pressure
30

in

the

(typically

20 bar absolute or higher during full load operation) during
all four strokes of its pressure/volume cycle.

That is, thesplit-cycle engine 10 is operable to time the XovrC valve 24
and the XovrE valve 26 such that the XovrC and XovrE valveswo 2011/115872

PCT/US2011/028284

13

are both open for a substantial period of time (or period of
crankshaft

rotation)

during whichtheexpansion piston

30

descends from its TDC position towards its BDC position andthe5compression piston

2 0 simultaneously ascends

BDC position towards its TDC position.
time
26(or crankshaft rotation)

are

both

transferred

open,
( 1)

a

crossover passage 22 and
10

to

the

period,from

expansion

equal

mass

of

cylinder

air

is

into

the

from the crossover passage 22
14.

Accordingly,

duringthisthe pressure in the crossover passage is prevented

dropping(typically15

During the period ofcompression cylinder 12
(2)

its

that the crossover valves 24,

substantiallyfrom the

from

20,

below

a

predetermined

minimum

30,

40

bar

duringorabsolutepressure
full

load

operation).

Moreover,engine cycle(typically 80% of the entire engine cycle orgreater),during a substantial portion of thethe XovrC valve

24

and XovrE valve

26

are bothclosed to maintain the mass of trapped gas in the crossover
passage 22 at a substantially constant level.

As a result,the pressure in the crossover passage 22 is maintained at a20

predetermined minimum pressureduringallfourstrokesofmethodofhavingthethe engine's pressure/volume cycle.
For

purposesherein,the

XovrC 24 and XovrE 26 valves open while the expansion piston
30 is descending from TDC and the compression piston 20 is25

ascending toward TDC in order to simultaneously transfer a
substantially

equal

mass

of

gas

into

and

out

of

the

crossover passage 22 is referred to herein as the Push-Pullmethod of gas
enables30

thetransfer.

pressure

in

It

is

the

Push-Pull method thatthecrossoverpassage

22

of

the

split-cycle engine 10 to be maintained at typically 20 bar
or higher during all four strokes of the engine's cycle whenthe engine is operating at full load.

wo 2011/115872

PCT/US2011/028284

14

As

discussed

disposedintheseparatefromearlier,theexhaust

port

of

the

cylinderpassage

22.

The

exhaustthe

35

crossoverarrangement of the exhaust valve 34
5

the crossover passage 22,

valve

34

is

head

33

structural

not being disposed inand therefore the exhaust port 35

notsharing any common portion with thecrossover passage

22,

is preferred in order to maintain the trapped mass ofgas in the crossover passage 22 during the exhaust stroke.
Accordingly,
10

large

cyclic drops

in pressure

are prevented

which may force the pressure in the crossover passage below
the predetermined minimum pressure.
XovrE valve 26 opens shortly before the expansion

15

piston30

reaches

its

time,

the

pressure

top dead center position.

ratio

of

the

pressure

At

in

this

crossoverpassage 22 to the pressure in expansion cylinder 14 is high,due to the fact that the minimum pressure in the crossover
passageistypically20

barabsoluteorhigherandthepressure in the expansion cylinder during the exhaust stroke
is typically about one to two bar absolute.
20

when XovrE valve 26 opens, the pressure in crossover passage
22

issubstantially higher than the pressure

cylinder 14
This

high

and/or25

In other words,(typically in the order of 20 to 1 or greater).
pressurefuelhigh speeds.

ratio

chargetocausesflow

initial

into

flow

expansion

the30

advantageous

it causes

split-cycle

pressures

the
14

air
at

These high flow speeds can reach the speed ofparticularly

becauseofcylindersound, which is referred to as sonic flow.
isin expansion

even

a

to

This sonic flow

split-cycle

rapid combustion event,engine10

tothoughignitionmaintainisengine10

which enables

highinitiatedcombustion
while

the

expansion piston 30 is descending from its top dead center
position.

wo 2011/115872

PCT/US2011/028284

15

The split-cycle air-hybrid engine 10 also includes
an air reservoir(tank)

40,

which is operatively connectedto the crossover passage 22 by an air reservoir (tank) valve
42.
5

Embodiments with two or more crossover passages 22 may

include a tank valve 42 for each crossover passage 22, whichconnect to a common air reservoir 40,

or alternatively eachcrossover passage 22 may operatively connect to separate air
reservoirs 40.
The tank valve 42 is typically disposed in an air
10reservoir(tank)

passage 22

toasecond44,

which

the air tank 40.

divided into a
and

port

first
air

extends

crossover

The air tank port

air reservoir

reservoir

from(tank)(tank)

port

44

is

port section 46
section

4 8.

The

first air tank port section 46 connects the air tank valve
15

42 to the crossover passage 22, and the second air tank port
section 4 8 connects the air tank valve 42 to the air tank
40.

The

includesvolumetheofvolume

the
of

first
all

air

tank

additional

port

ports

sectionand46

recesses

which connect the tank valve 42 to the crossover passage 22
20

when the tank valve 42 is closed.
The tank valve 42 may be any suitable valve device
or system.

For example, the tank valve 42 may be an active

valve which is activated by various valve actuation devices(e.g.,
25

pneumatic,

Additionally,

hydraulic,the tank valve

system with two

cam,electricorthelike).

42 may comprise a tank valve

or more valvesactuated with two

or moreactuation devices.
Air

tank

40

is

utilized to

store

energy intheform of compressed air and to later use that compressed air
30

to

power

the

crankshaft

16,

as

described

intheaforementioned United States Patent No. 7,353,786 to Scuderi
et al.

This mechanical means for storing potential energy

providesnumerous

potential

advantages

over

the

current

wo 2011/115872

PCT/US2011/028284

16state of the art.

For instance,

the split-cycle engine 10

can potentially provide many advantages in fuel efficiency
gains

and

NOx

emissions

reductionatrelatively

lowmanufacturing and waste disposal costs in relation to other5

technologies

on

the

market,such

asdieselengines

andelectric-hybrid systems.
Byclosingofselectively
the

air

tank

controlling

the

valve

thereby42

andopening

and/orcontrolling

communication of the air tank 40 with the crossover passage
1022,

the split-cycle air-hybrid engine 10 is operable in an

Engine Firing

(EF)

mode,

an Air Expander

(AE)

mode,

an AirCompressor (AC) mode, an Air Expander and Firing (AEF) mode,
and a Firing and Charging (FC) mode.

The EF mode is a non-hybrid mode in which the engine operates as described above
15

without the use of the air tank 40.

The AC and FC modes areenergymode

storagemodes.

The

AC

is

an

air-hybrid

operating mode in which compressed air is stored in the air
tank

20

40

without

combustion

cylinder14(i.e.,

utilizingthekinetic

engineduring braking.

10

nooccurringfuelenergyintheexpenditure) ,expansion

such

as

by
the

of

a

vehicleincluding

The

FC

mode

an

is

air-hybrid

operating mode in which excess compressed air not needed for
combustion isstored in the air tank 40,

than full engine load25

at constant speed) .
mode

has

an

(e.g.,

engine idle,

such asatlessvehicle cruising

The storage of compressed air in the FCenergycost(penalty);

therefore,itisdesirable to have a net gain when the compressed air is usedat alater time.

usage modes.
30

The AE and AEF modes are stored energy

The AE mode is an air-hybrid operating mode inwhich compressed air stored in the air tank 40 is used todrive the expansion piston 30 without combustion occurringin the expansion cylinder 14
The

AEF

mode

is

an

(i.e.,

air-hybrid

no

fuel

operatingexpenditure).
mode

in

which

wo 2011/115872

PCT/US2011/028284

17

compressed air stored in the air tank 40 is utilized in the
expansion cylinder 14 for combustion.
In

5

the

AC

mode,

the

expansion

preferably deactivated to minimizeorpumping work

IMEP)

(in termsof negative

cylinder14issubstantially reduce
performed by the

expansion piston 30 on air in the expansion cylinder.
will

be

discussedinfurther

detailherein,

the

As
most

efficient way to deactivate the expansion cylinder 14 is tokeep the XovrE valve 26 closed through the entire rotation of10

the crankshaft 16,

and ideally to keep the exhaust valve 34

open through the entire rotation of the crankshaft.
In engine embodiments where

the exhaust valve

isoutwardly opening, the exhaust valve may be kept open throughthe15

entirerotation

exemplaryofembodimentthecrankshaft.

illustrates

However,

the

more

this

typicalconfiguration where the exhaust valve 34 is inwardly opening.
Therefore,

in order to avoid expansion piston 30 to exhaust

valve 34 contact at the top of the expansion piston's stroke,the20

exhaust

valve

34

must

be

closed

prior

to

when

the

ascending piston 30 makes contact with the inwardly opening
valve 34.
Additionally,
trapped

air

is

not

it

is

compressed

important

to

too

from

much

insure
the

that

the

angle

of

exhaust valve closing to TDC of the expansion piston in order
25

to

avoid

Generally,

excessivetemperatureandpressurebuild-up.

this means that the residual compression ratio at

the point of exhaust valve 34 closing should be 20 to 1 orless,and more preferably 10

to

1 or

less.

In exemplaryengine 10, the residual compression ratio will be about 20 to
30

1 at an exhaust valve 34 closing angle (position) of about 60
CA

degreesexhaustbefore

valve

TDC

of

the

expansion

piston30.

closingis60

CA degrees

before

TDC,

When
it

is

wo 2011/115872

PCT/US2011/028284

18highly desirable (as discussed in greater detail herein) thatexhaust valve opening be 60 CA degrees after TDC.
Accordingly,

in order to deactivate the expansion

cylinder 14 without excessive build-up of air temperature and5pressure,

it is preferable that the exhaust valve 34 be kept

open through at least 240 CA degrees of the rotation of the
crankshaft

16.

Moreover,

it

is

more

preferable

that

the

exhaust valve 34 be kept open through at least 270 CA degrees
of
10

the

rotation

preferable

that

of

the

the

crankshaft

16,

and

kept

open

exhaust valve be

it

is

most

throughat

least 300 CA degrees of rotation of the crankshaft 16.
Astheexhaust

valve

34

is

closedsolelyin

response to avoiding expansion piston 30 to exhaust valve 34
contact,
15

occur

as

position

air compression(and therefore negative work)

piston30

ascends

toward

its

top

dead

(TDC).

In order to maximize efficiency,

will

centera primaryaim is therefore to reopen the exhaust valve 34 at a timing
when the pressure in the expansion cylinder 14 is equal tothe pressure in the exhaust port 35 (i.e., when the pressure
20

differential

betweenthe

expansion

cylinder

14

and

the

exhaust port 35 is substantially zero)

In an ideal system,

the

valve

openingtimingoftheexhaust

34

would

be

symmetrical with the closing timing of the exhaust valve 34
about top dead center of the expansion piston 30.
25

in practice,

However,

after the exhaust valve 34 closes during theexhaust stroke of the expansion piston 30,

the pressure andtemperature

beginstotocylinder

Some

of

in

the

the

expansion

heat

generatedcylinder
is

14

lost

the

rise.

components such as the cylinder walls, the piston crown, and30

the cylinder head.

Therefore, the pressure in the expansion

cylinder 14 and exhaust port 35 is equalized at a slightly
earlier
expansion

timingstroke(relative
of

the

to

top

dead

center)ontheexpansion

piston

30

on

the

than

wo 2011/115872

PCT/US2011/028284

19exhaust stroke.

In addition,

wave effects

in the exhaust

port 35 and the flow characteristics of the exhaust valve 34(such as the fact that flow is quite restricted at low valve
lifts)
5

theresult in the optimum closing and opening timing of

exhaustvalve

18

deviatingslightly

from

truly

to

the

closingsymmetrical about top dead center.
Therefore,
position(timing)

substantially
10

it

is

importantand opening position(i.e.,

within

plus

or

keep

(timing)minus

of valve 34

10

CA degrees)

symmetrical with respect to TDC of piston 30,

in order toreturn as much of the compression work to the crankshaft 16
as possible.

For example, if the exhaust valve 34 is closed

at substantially 25 CA degrees before TDC of the expansion

15

piston

30

valve

34

to

avoid being hit by theshould open at

TDC of piston 30.

piston30,

thensubstantially 25 CA degrees

In this way,

the

after

the compressed air will act

as an air spring and return most of the compression work to
the crankshaft 16 as the air expands and pushes down on the
expansion piston 30 when the piston 30 descends away from20

TDC.
Accordingly, in order to avoid expansion piston 30
to25

exhaustvalve

34

contactandtopreferable

compression

work

as

possible,itclosing

opening

positions(timing)

andsymmetrical,

isreverseof(e.g.,

25 CA degrees before TDC,

30

preferable

if

the

that

the

34

are

about TDC

if exhaust valve 34 closes atthen it must open at 25 plus orminus 10 CA degrees after TDC of piston 30).
more

much

valve

within plus or minus 10 CA degrees,of expansion piston 30

asclosingandopening

However, it ispositionsofvalve 34 are symmetrical, within plus or minus 5 CA degrees,
about TDC of piston 30,
and opening positions

and most preferable if the closingof valve34

aresymmetrical,

plus or minus 2 CA degrees, about TDC of piston 30.

withinwo 2011/115872

PCT/US2011/028284

20
Also,
preferably

in

the

AC mode,theopenedwhen

thepressureair

airtank valve
in

the

42

is

crossoverpassage 22 is higher than the air pressure in the air tank40.
5This ensures that compressed air will flow into the air

tank

40

for

storage,

and

that

compressed

air

will

substantially be prevented from leaking out of the air tank.
The

compression

piston20

draws

intake

air

into

the

compression cylinder 12 and compresses the intake air.

The

compressed air is then stored in the air tank 40.
10

As

shown

in

XoverE open Exh clsd,
of negative IMEP)

FIG.

graph

2

labeled:the greatest pumping losses

occur in the AC mode if the XovrE valve is

kept open and the exhaust valve is kept closed.
work
15

in

this

arrangement

also

generally

The pumping

increases

withengine speed.
Referring

FIG.

to

XoverE std- Exh std,
XoverE open Exh std,nearly20(in terms

equal

the

valve

are

labeled:XoverE clsd Exh std,

and

from
( i)

operated withused for the EF mode);graphspumpingamounts

arrangement if either:2

lossesthearereducedXoverE open Exh clsd

the XovrE valve and the exhauststandard timing(ii)(e.g.,

thetimingthe XovrE valve is kept closed

and the exhaust valve is operated with standard timing;
(iii)
25

or

the XovrE valve is kept open and the exhaust valve isoperated with standard timing.
Referring
XoverE clsd_Exh open,
lossesarereducedengine speeds)
30

at

to

FIG.

as

discussedevenfurther2

graphearlier,(tonearlylabeled:thepumping

zero

at

low

if the expansion cylinder is deactivated bykeeping the XovrE valve closed and the exhaust valve open.
In this arrangement,

the expansion piston draws

in exhaust

air from the exhaust port during its power stroke and pushes
air back into the exhaust port during its exhaust stroke.

Awo 2011/115872

PCT/US2011/028284

21
minimum

amountexhaustvalve

contact

with

that
5

of
34

work

closedinisexpansion

compression

closingcompression

timings

piston

30.

to

of

exhaust

valve

34

of

expansion

TDC

Thus,

apparent

that

when

the

expansionand substantially reduces

since

the

are

cylindertheavoiding

Additionally,

reversibletominimizes

responseisrelative

is

done,

work

symmetrical
it

only

is

most

of

openingandsubstantiallypiston30.

deactivation

pumping work performedby the expansion piston in the AC mode.
10

Althoughreference to atheinventionhas

specific embodiment,

been

described

byit should be understoodthat numerous changes may be made within the spirit and scopeoftheinventive

concepts

described.

Accordingly,itisintended that the invention not be limited to the described15

embodiment,

but thatit havethelanguage of the following claims.

full

scope defined by thewo 2011/115872

PCT/US2011/028284

22
CLAIMS

What is claimed is:
1.
5

A split-cycle air-hybrid engine comprising:a crankshaft rotatable about a crankshaft axis;acompression

compression
crankshaft

cylinder
such

that

pistonslidablyandoperatively

thecompression

received withinconnected

pistontoathe

reciprocatesthrough an intake stroke and a compression stroke during a10

single rotation of the crankshaft;anexpansion

expansion

cylindercrankshaft

suchpistonandthat

slidably

operatively

theexpansion

received withinanconnected

thepistontoreciprocatesthrough an expansion stroke and an exhaust stroke during a15

single rotation of the crankshaft;an exhaust valve selectively controlling gas flowout of the expansion cylinder;a20

crossoverpassageinterconnecting

thecompression and expansion cylinders,the crossover passage

includinga(XovrC)

crossover

expansion

crossovercompression(XovrE)

valve

valve

and

a

pressuredefiningachamber therebetween;ancrossover25

airreservoir

passageandoperatively

selectively

connected

operable

to

to

the
store

compressed air from the compression cylinder and to delivercompressed air to the expansion cylinder; andan air reservoir valve selectively controlling air
flow into and out of the air reservoir;
the30

engine(AC) mode, wherein,

being

operablein the AC mode,

in

an

Air

Compressor

the XovrE valve is kept

closed during an entire rotation of the crankshaft,and theexhaust valve is kept open for at least 240 CA degrees ofthe same rotation of the crankshaft.

wo 2011/115872

PCT/US2011/028284

232.
wherein,at

The split-cycle air-hybrid engine of claim 1,

in the AC mode,least

the exhaust valve is kept open for

270

CA

degrees

of

the

same

rotation

of

the

3.

The split-cycle air-hybrid engine of claim 1,

crankshaft.
5

wherein,atin the AC mode,least

the exhaust valve is kept open for

300

CA

degrees

of

the

same

rotation

of

the

4.

The split-cycle air-hybrid engine of claim 1,

crankshaft.

10

wherein,in the AC mode,a residual compression ratio at an

exhaust valve closing position is 20 to 1 or less.
5.
wherein,

The split-cycle air-hybrid engine of claim 1,

in the AC mode,a residual compression ratio at an

exhaust valve closing position is 10 to 1 or less.
15

6.
wherein,

The split-cycle air-hybrid engine of claim 1,

in the AC mode,the exhaust valve closing positionand exhaust valve opening position are symmetrical,

withinplus

center

or

minus

10

CA

degrees,

about

the

top

dead

position of the expansion piston.
20

7.
wherein,

The split-cycle air-hybrid engine of claim 1,

in the AC mode,the exhaust valve closing positionand exhaust valve opening position are symmetrical,

withinplus

center

or

minus

5

CA

degrees,

about

the

top

dead

position of the expansion piston.
25

8.
wherein,

The split-cycle air-hybrid engine of claim 1,

in the AC mode,the exhaust valve closing positionand exhaust valve opening position are symmetrical,

withinplus

center

or

minus

2

CA

degrees,

about

the

top

dead

position of the expansion piston.
30

9.
wherein,in

The split-cycle air-hybrid engine of claim 1,
the

AC

mode,

the

exhaustvalve

isduring the entire same rotation of the crankshaft.

kept

open

wo 2011/115872

PCT/US2011/028284

24

10.

The split-cycle air-hybrid engine of claim 1,

wherein, in the AC mode, the compression piston draws in andcompresses intake air which is stored in the air reservoir.
11.
5

wherein,

The split-cycle air-hybrid engine of claim 1,

in the AC mode,

the air reservoir valve is opened

when air pressure in the crossover passage is higher thanair pressure in the air reservoir.
12.

A split-cycle air-hybrid engine comprising:a crankshaft rotatable about a crankshaft axis;
10acompression

compression
crankshaft

cylinder
such

that

pistonslidablyandoperatively

thecompression

received withinconnected

pistontoathe

reciprocatesthrough an intake stroke and a compression stroke during asingle rotation of the crankshaft;
15

anexpansion

expansion

cylindercrankshaft

suchpistonandthat

slidably

operatively

theexpansion

received withinanconnected

thepistontoreciprocatesthrough an expansion stroke and an exhaust stroke during asingle rotation of the crankshaft;
20

an exhaust valve selectively controlling gas flowout of the expansion cylinder and into an exhaust port;a25

crossoverpassageinterconnecting

thecompression and expansion cylinders,the crossover passage

includinga(XovrC)

crossover

expansion

crossovercompression(XovrE)

valve

valve

and

a

pressuredefiningachamber therebetween;ancrossoverairreservoir

passageandoperatively

selectively

connected

operable

to

to

the
store

compressed air from the compression cylinder and to deliver30

compressed air to the expansion cylinder; andan air reservoir valve selectively controlling air
flow into and out of the air reservoir;

wo 2011/115872

PCT/US2011/028284

25

the

engine(AC) mode, wherein,

being

operablein the AC mode,

in

an

Air

Compressor

the XovrE valve is kept

closed during an entire rotation of the crankshaft,and theexhaust valve is opened at a position at which pressure in5

the expansion cylinder is approximately equal to pressure in
the exhaust port.
13.

A

methodofoperatingasplit-cycle

air-hybrid engine including:a crankshaft rotatable about a crankshaft axis;
10acompression

compression
crankshaft

cylinder
such

that

pistonslidablyreceived

withinandoperatively

connected

tothecompression

pistonathe

reciprocatesthrough an intake stroke and a compression stroke during asingle rotation of the crankshaft;
15

anexpansion

expansion

cylindercrankshaft

suchpistonandthat

slidablyreceived

withinanoperatively

connected

to

the

the

expansion

pistonreciprocatesthrough an expansion stroke and an exhaust stroke during asingle rotation of the crankshaft;
20

an exhaust valve selectively controlling gas flowout of the expansion cylinder;a25

crossoverpassageinterconnecting

compression and expansion cylinders,theincludinga(XovrC)

crossover

expansion

crossovercompression(XovrE)

valve

the

crossover passage
valve

and

a

pressuredefiningachamber therebetween;ancrossoverairreservoir

passageandoperatively

selectively

connected

operable

to

to

the
store

compressed air from the compression cylinder and to deliver30

compressed air to the expansion cylinder; andan air reservoir valve selectively controlling air
flow into and out of the air reservoir;

wo 2011/115872

PCT/US2011/028284

26
theenginebeing

operable

in

an

Air

Compressor

closed during

an entire(AC) mode;the method including the steps of:
keeping5

the XovrE

valverotation of the crankshaft; andkeeping the exhaust valve open during at least 240
CA degrees of the same rotation of the crankshaft;whereby the expansion cylinder is deactivated toreduce pumping work performed by the expansion piston on air

10

in the expansion cylinder.
14.
valve

The method of claim 13,

closing

position

positionsymmetrical,

and

the

withinplus

keeping the exhaust

exhaust

valve

or

5

minus

opening

CA degrees,

about the top dead center position of the expansion piston.
15

15.
keepingtheThe method of claim 13, including the step of
exhaust

valve

open

duringtheentiresamerotation of the crankshaft.
16.

The method of claim 13, further including thesteps of drawing intake air into the compression cylinder,
20

compressing the intake air,and storing the compressed air

in the air reservoir.
17.

The method of claim 13, further including thestep of opening the air reservoir valve when air pressure in
the crossover passage is higher than air pressure in the air
25

reservoir.

wo 2011/115872

PCT/US2011/028284

1/2

FIG. 1

:.;;
0
N
0

--""""""""""""

FIG 2

Ut

QCI

-..l
N

Expander cylinder deactivation
0-1

Expander deactivation -IMEP- - - --- --- ---~--------- ------1--------~--------------.:.:.:

--

1\J
1\..)

IMEP (bar) -2~----------------KoverE st ~ Exh std ------ ......
-3.........

- - KoverE cl pd_Exh_oF en.............
KoverE-cl ~d Exh stc ~----- KoverE-o~ ~en Exh c sd
KoverE=o~ ~en --Exh --s d...... ......

.......

-----

-4
1000

1500

2000

2500
Engine RPM

'"d

("")

g
00
N
0

3000

3500

4000

"""

0N"""
QCI

N

QCI

"'"

INTERNATIONAL SEARCH REPORTInternational application No.
PCTIUS2011/028284

A.

CLASSIFICATION OF SUBJECT MATIER

IPC(8)- F02B 33/22 (2011.01)
USPC- 123fiOR
According to International Patent Classification (I PC) or to both national classification and IPC
B.

FIELDS SEARCHED

Minimum documentation searched (classification system followed by classification symbols)
IPC(8)- F02B 3100, 11/00, 19/06, 33/00, 33/02, 33/06, 33/22, 41/02, 41/04, 41/06 (2011.01)
USPC- 60/620,712; 123126, 27R, 52.3, 52.5, 53.1, 53.5, 58.8, 68, 70R, 70V, 253, 258, 286, 292; 180/165, 302
Documentation searched other than minimum documentation to the extent that such documents are included in the fields searchedElectronic data base consulted during the international search (name of data base and, where practicable, search terms used)
Pat Basec.

DOCUMENTS CONSIDERED TO BE RELEVANT

Category*

Citation of document, with indication, where appropriate, of the relevant passages

Relevant to claim No.

X

US 2007/0157894 A1 (SCUDERI et al) 12 July 2007 (12.07.2007) entire document

1-17

A

US 7,607,503 81 (SCHECHTER) 27 October 2009 (27.10.2009) entire document

1-17

A

US 2010/0051003 A1 (NEGREet al) 04 March 2010 (04.03.2010) entire document

1-17

A

US 4,696,158 A (DEFRANCISCO) 29 September 1987 (29.09.1987) entire document

1-17

D

D Further documents are listed in the continuation of Box C.
•

"A"
"E"
"L"

"0"

"P"

Special categories of cited documents:
document defining the general state of the art which is not considered
to be of particular relevanceearlier application or patent but published on or after the international
filing datedocument which may throw doubts on priority claim(s) or which iscited to establish the publication date of another citation or otherspecial reason (as specified)
document referring to an oral disclosure, use, exhibition or othermeans
document published prior to the international filing date but later thanthe priority date claimed

Date of the actual completion of the international search
03May 2011
Name and mailing address of the ISAIUS
Mail Stop PCT, Attn: ISAIUS, Commissioner for Patents
P.O. Box 1450, Alexandria, Virginia 22313-1450
Facsimile No. 571-273-3201
Form PCTIISN210 (second sheet) (July 2009)"T'

later document published after the international filing date o1eriority
date and not in conflict with the apClication but cited to un erstandthe principle or theory underlying t e invention"X'' document of particular relevance; the claimed invention cannot be

considered novel or cannot be considered to involve an inventive
step when the document is taken alone"Y" document of particular relevance; the claimed invention cannot be

considered to involve an inventive step when the document iscombined with one or more other such documents, such combination
being obvious to a person skilled in the art"&" document member of the same patent family

Date of mailing of the international search report

1 1 MAY 2011
Authorized officer:
Blaine R. Copenheaver
PCT Helpdesk: 571·272-4300
PCT OSP: 571·272·7774