(11) Application No. AU 2011227531 B2(12) STANDARD PATENT(19) AUSTRALIAN PATENT OFFICE
(54)

Title
Split-cycle air-hybrid engine with compressor deactivation(51)

International Patent Classification(s)F02B 25/00 (2006.01)
F02B 41/06 (2006.01)
F02B 33/22 (2006.01)(21)

Application No:

2011227531

(22)

(87)

WIPO No:(30)

Priority Data

(31)

Number61/363,825
61/365,343
61/313,831

(32)

(43)
(44)

Publication Date:
Accepted Journal Date:

2011.09.22
2012.11.01

Date of Filing:

2011.03.14

W011/115870

Date2010.07.13
2010.07.18
2010.03.15(33)

Country
US
US
US

(71)

Applicant(s)Scuderi Group, LLC(72)

Inventor(s)Meldolesi, Riccardo;Badain, Nicholas;Gilbert, Ian(74)

Agent / Attorney
Davies Collison Cave, Level 14 255 Elizabeth Street, Sydney, NSW, 2000

(56)

Related Art
US 4630447 A
US 20070017203 Al
US 7628126 B2
US 20030014971 Al
US 20040255882 Al
US 20070157894 Al
US 20080105225 Al
US 20080202454 Al
US 20090038596 Al
US 20090038598 Al
US 20090301086 Al
US 20040139934 Al
US 20060124085 Al
US 4359979 A
US 20090266347 Al

(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)IN(19) World Intellectual Property Organization
International Bureau(10) International Publication Number(43) International Publication DateW O 2011/115870 Al

PCT

22 September 2011 (22.09.2011)(51) International Patent Classification:
F02B 25/00 (2006.01)
F02B 41/06 (2006.01)
F02B 33/22 (2006.01)(21) International Application Number:
PCT/US2011/028281(22) International Filing Date:

BADAIN, Nicholas; 37 Rosslyn Road, Shoreham-By
Sea, West Sussex BN43 6WL (GB). GILBERT, Ian; 67
Beach Green, Shoreham-By-Sea, West Sussex BN43 5YE(GB).
(74) Agents: FILDES, Christoher, J. et al.; Fildes & Out
land, P.C., 20916 Mack Avenue, Suite 2, Grosse Pointe(71) Applicant (for all designated States except US): SCUDERI GROUP, LLC [US/US]; 1111 Elm Street, Suite 33,
West Springfield, MA 01089 (US).

Woods, MI 48236 (US).
(81) Designated States (unless otherwise indicated,for every
kind of nationalprotection available): AE, AG, AL, AM,
AO, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ,
CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO,
DZ, EC, EE, EG, ES, Fl, GB, GD, GE, GH, GM, GT,
HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP,
KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD,
ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI,
NO, NZ, OM, PE, PG, PH, PL, PT, RO, RS, RU, SC, SD,
SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR,
TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW.

(72) Inventors: MELDOLESI, Riccardo; 55 New Road,
Shoreham-By-Sea, West Sussex BN43 6RB (GB).

(84) Designated States (unless otherwise indicated,for every
kind of regionalprotection available): ARIPO (BW, GH,

14 March 2011 (14.03.2011)(25) Filig Language:(26) Publication Language:(30) Priority Data:
61/313,831
61/363,825
61/365,343

EnglishEnglish15 March 2010 (15.03.2010)13 July 2010 (13.07.2010)18 July 2010 (18.07.2010)

US
US
US

[Continued on next page](54) Title: SPLIT-CYCLE AIR-HYBRID ENGINE WITH COMPRESSOR DEACTIVATION

FIG. 1
40

44
18

48

24

46

A

35

19-

161

N2
38

203

00

C3

10
34

(57) Abstract: A split-cycle air-hybrid engine includes a rotatable crankshaft.
A compression piston is slidably received within a compression cylinder andoperatively connected to the crankshaft. An intake valve selectively controls
air flow into the compression cylinder. An expansion piston is slidably received within an expansion cylinder and operatively connected to the
crankshaft. 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 op
eratively connected to the crossover passage. In an Air Expander (AE) mode
and an Air Expander and Firing (AEF) mode of the engine, the XovrC valve is
kept closed during an entire rotation of the crankshaft, and the intake valve is
kept open for at least 240 CA degrees of the same rotation of the crankshaft.

II
W O 2011/115870 A 1|llll
GM, KE, LR, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG,
ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ,
TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK,
EE, ES, Fl, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU,
LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK,l|lllll ||||||||||||||I||||||| I| |I| | | | V| |I |SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ,
GW, ML, MR, NE, SN, TD, TG).
Published:with internationalsearch report (Art. 21(3))

WO 2011/115870

PCT/US2011/028281

SPLIT-CYCLE AIR-HYBRID ENGINE WITH COMPRESSOR DEACTIVATIONTECHNICAL FIELD

This invention relates to split-cycle engines and,more

5particularly,

tosuch anengineincorporating

an

air

hybrid system.

BACKGROUND OF THE INVENTION

For

10

engine"aspurposesusedininternal combustion

of

the

clarity,present

enginewell-known

Otto

compression,

expansion

the

cycle

term

"conventional

application

wherein(i.e.,

allthe(or power)

four

referstoanstrokes of theintake(orand exhaust

inlet),

strokes)

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

Each

strokerequiresone half revolution(180 degrees crank angle
the crankshaft(CA)),of the crankshaft

and two full

revolutionsof(720 degrees CA) are required to complete theentire Otto cycle in each cylinder of a conventional engine.
Also,
20

definition

is

for

purposesofferedofclarity,thefor the term "split-cycle

following
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

30

compression
cylindercrankshaft

suchthrough an

intakethatpistonslidablyandoperatively

thecompression

received withinconnected
pistonstroke and a compression

single rotation of the crankshaft;

SUBSTITUTE SHEET (RULE 26)

to

a

the

reciprocatesstroke during a

WO 2011/115870

PCT/US2011/028281

2
anexpansion

within an expansion
the crankshaft(power) piston

slidably

cylinder and operatively

received

connected

tosuch 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

disposed therein,
10

compressionacrossoverinterconnecting

the

the

crossover passage

expansion(XovrE) valve

but more preferably including a crossover(XovrC)valve and a crossover expansion(XovrE)valve-defining a pressure chamber therebetween.
United8,

2003

granted
15

are

to

StatesScuderi

October

discussion
addition,ofand United

11,

incorporated

Patent2005

herein6,543,225

Statesto Branyon
bysplit-cycle

these patents

No.

Patentetreference,

and

al.,

No.

containdetails

April

6,952,923

both of whichsimilar-type

disclose

grantedanextensiveengines.

of priorIn

versionsof an engine of which the present disclosure details.further
developments.

20

Split-cycle
cycle

engineanairThis combination

enables

store

the

energyreservoir.
25

with

air-hybrid

inengines

reservoir

anda split-cycle

form

of

combineavariouscontrols.

split

air-hybrid engine tocompressed

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

compression piston
cylindercrankshaft

suchthrough an

intakethat

slidablyreceived

withinandoperatively

connected

tothecompression

pistonstroke and a compression

single rotation of the crankshaft;

SUBSTITUTE SHEET (RULE 26)athereciprocatesstroke during a

WO 2011/115870

PCT/US2011/028281

3
anexpansion

within an expansion(power)cylinderpistonslidablyand operatively

received

connected tosuch that the expansion piston reciprocatesthe crankshaft

through an expansion stroke and an exhaust stroke during a5single rotation of the crankshaft;acrossovercompression
including(port)and expansion cylinders,
at

least

disposed therein,
10

passagecompressionacrossoverinterconnecting

thethe crossover passage

expansion(XovrE) valve

but more preferably including a crossover(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
8,

20

2008

Statesto Scuderi et al.,reference,contains

air-hybrid

andpatentPatentanextensive

details

7,353,786

which issimilar-type

discloses

No.

April

incorporated herein by

discussion

engines.

of prior

grantedIn

hybridofsplit-cycle

addition,
systems

thisof whichthe present disclosure details further developments.
A split-cycle
normalthe25

operatingEnginemodes.

Inor

Firingthereservoir.

connecting
remains
30

firing

(NF)

(EF)

mode)

EF mode,hybrid split-cycle
air

air-hybrid

In

the

mode

and

closed to isolate

runcommonly

basic

functionsinacalledair-hybrid

asa non-airoperating without the use of its

EF mode,crossovercan be

(also

four

the engine

engine,theenginepassagethe air

a

tank
to

valve
the

reservoir

operatively

airreservoir

from the basic

split-cycle engine.
The

split-cycle

air-hybrid

engineoperates

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

SUBSTITUTE SHEET (RULE 26)

with

The fourWO 2011/115870

PCT/US2011/028281

4
1)

Air

Expandercompressed

(AE)

mode,

energy

air

which

from

includes

the

air

using

reservoir

without combustion;
2)
5

Air Compressor(AC)compressedenergy

air

mode,

which
into

includes storing

the

air

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)

mode,

which

includesair

energy

into

the

air

AE,

AC,

reservoir with combustion.
However,further

AEF and FC,
15

isoptimizationof thesedesirable to enhancemodes,. EF,

efficiency and reduce

emissions.

SUMMARY OF THE INVENTION

The present invention provides a split-cycle air
20

hybrid engine in which the use of the Air Expander (AE) modeand the Air Expander and Firing (AEF) mode are optimized forpotentiallyanyvehicle

in

any

drive

cycle

for

improved

efficiency.
More
25

particularly,

an exemplary

embodimentofasplit-cycle air-hybrid engine in accordance with the present
invention includes a crankshaft rotatable about a crankshaft
axis.

A compression

compression30cylinderpistonisslidablyandoperatively

thecompression

received withinconnected

crankshaft

suchthrough an

intake stroke and a compression

singlethatrotationofthepistoncrankshaft.

to

a

the

reciprocatesstroke during aAn

intakevalve

selectively controls air flow into the compression cylinder.
An expansion piston is slidably received within an expansion

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

5cylinderand. operatively

connected

to the crankshaft

suchthat the expansion piston reciprocates through an expansion
stroke and an exhaust stroke during a single rotation of the
crankshaft.
5Acrossoverpassageinterconnects

thecompression and expansion cylinders.

The crossover passage

includes(XovrC)acrossovercompression

crossover

expansion(XovrE)

chamber

therebetween.

An

valve

air

valve

and

a

pressuredefining

reservoirisaoperatively

connected to the crossover passage and selectively operable
10

to store compressed air from the compression cylinder and todeliver compressed air to the expansion cylinder.

An airreservoir valve selectively controls air flow into and outof theair reservoir.

Expander
15

(AE)

mode

The

engineisoperableand an Air Expandermode.

In the AE and AEF modes,

closedfor anentireandin

an AirFiring(AEF)

the XovrC valve

rotation of the

crankshaft,

is

kept

and

the

intake valve is kept open for at least 240 CA degrees of thesame rotation of the crankshaft.
A method
20ofoperatingengine.is also disclosed.

asplit-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

connectedthat the compression piston25

tocrankshaft

suchreciprocates through an intake

stroke and a compression stroke during a single rotation of
the crankshaft.

Anintake valve

selectively

flow into the compression cylinder.
slidablyreceived

expansionthecrankshaft

expansion piston

reciprocatesthrough anandstrokeanconnected

exhaustcrankshaft.

withinA

toduringcrossoveracontrols

airAn expansion piston isanoperatively
30

thecompression and expansion cylinders.

such

and

that

the

expansion

strokerotationoftheinterconnects

thesinglepassagecylinderThe crossover passage

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

6
includesacrossovercompression

crossover

expansion(XovrE)

chamber

therebetween.

An(XovrC)

valve

air

valve

and

a

pressuredefining

reservoirisaoperatively

connected to the' crossover passage and selectively operable
5

to store compressed air from the compression cylinder and todelivercompressed

reservoir

valve

of

the

air

mode.

(AE) mode

the

the

selectively

The method

includes

to

and
in

expansion

cylinder.

An

air

and

out

controls

air

flow

The

engineisoperableanAirreservoir.

Expander10

airaccordance

following

same

15

intake

valve

and

with

present

steps:

thekeepingrotation

cylinder

is

of

open

for

the

crankshaft,atinExpandertheclosed for an entire rotation of the crankshaft;
the

into

least

240 CA
wherebyFiring(AEF)

invention

XovrC

valve

and keeping

degreesthean Airofthecompression

deactivated to reduce pumping work performed by

the compression piston on intake air.

invention

These

and

other

will

be morefeaturesandfully understoodadvantages
from theof

thefollowingdetailed description of the invention taken -together with the20

accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGSIn the drawings:
25

FIG.

1 is

a lateral sectional view of an exemplary

split-cycle air-hybrid engine inaccordance with the present

invention; and

FIG.

2 is

a graphicalillustrationof pumping load(in terms of negative IMEP) versus engine speed in accordance30

with the present invention.

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

7
DETAILED DESCRIPTION OF THE INVENTION

The following glossary of acronyms and definitionsof terms used herein is provided for reference.
5

In General
Unless otherwise
closing timings

specified,

are measured

inall valve opening andcrank angle degrees

after

top dead center of the expansion piston (ATDCe).
Unless10otherwise

specified,

all

valve

durations

are in crank angle degrees (CA).

Air tank (or air storage tank): Storage tank for compressed
air.
ATDCc: After top dead center of the compression piston.
ATDCe: After top dead center of the expansion piston.
15

20

Bar: Unit of pressure, 1 bar
BMEP:

Brake

referstooutputshaft),

for.

Brake

brake

torque output

pressure

thebyparameter

effective

as

after

friction

losses

Effective

Pressuredeliveredexpressed

value.

The

pressure.

output

Mean

(MEP)

divided25

mean

105 N/M 2

=

BMEP

to

the

term

."Brake"crankshaft(FMEP)

are(BMEP)

is(or

accounted

theengine's

in

terms

of a mean effective

is

equal

to

enginedisplacement.

taken

after

the

This

the

is

losses

brake

the

due

torqueperformancetofriction.

Accordingly, BMEP=IMEP-friction.

Friction, in this case isusuallyofalso

expressed

in

terms

an

MEP

value

known

its

associatedits

associatedasFrictional Mean Effective Pressure (or FMEP).
Compressor:

The

compression

cylinderandcompression piston of a split-cycle engine.
Expander:30

The

expansion

cylinderandexpansion piston of a split-cycle engine.
FMEP:

Frictional Mean Effective Pressure.

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

8
IMEP:

Indicated

Effective

Pressure.

The

term

refers to the output as delivered to the top of"Indicated"

5

Mean

the piston, before friction losses(FMEP) are accounted for.

Inlet

Also commonly(or intake) :Inletvalve.

referred toas the intake valve.
Inlet

air

(or

intake

air):

Air

drawn

into

the

compression

cylinder on an intake (or inlet) stroke.
Inlet

valve

(or intake

valve):

Valve

controllingintakeofgas into the compressor cylinder.
10

Pumping work (or pumping loss): For purposes herein, pumping
work (often expressed as negative IMEP) relates to that partof engine
fuel

power which

and air

chargeis

expendedon theinduction of theinto theengineandtheexpulsion

Ratio

duringcompression

ofcombustion gases.

15

ResidualCompression

deactivation:
the

The

compression

intake

valve

ratio

(a/b) ofcylinderclosesto(a)the trappedcylindervolume

in

at

the

position

just

when

the

(b)

the

trappedvolumeinthecompression cylinder just as the compression piston reaches20

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

Tankvalve:

Valve

connecting

the

Xovr

passagewith

thecompressed air storage tank.

VVA:
25

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

and30

expansion

cylindersthrough

which

gas

flows

from

compression to expansion cylinder.
XovrC(or XoverC)

valves:Valvesatthethe Xovr passage.

SUBSTITUTE SHEET (RULE 26)

compressor

end of

WO 2011/115870

PCT/US2011/028281

9
XovrC-clsd-Int-clsd:

XovrC

valve

fully. closed

andIntake

XovrC

valve

fully

closedandIntake

XovrC

valve

fully

closedandIntakevalve fully closed.
XovrC-clsd-Int-open:
valve fully open.
5

XovrC-clsd-Int-std:

valve having standard timing.
XovrC-open-Int-clsd: XovrC valve fully open and Intake valve
fully closed.
XovrC-std-Int-std:
10

XovrC valve having

standard timing

andIntake valve having standard timing.
Referring to FIG. 1, an exemplary split-cycle air
hybrid engine is shown generally by numeral 10.

The split

cycle air-hybrid engine

cylinders

of
15

a

conventional

compression

enginecylindercylinder head 33 is

10 replaces
withtwo adjacentacombination

of

one

12 and one expansion -cylinder 14.

A

typically disposed over an open- end of

the expansion and compression cylinders 12,

14 to cover andseal the cylinders.
The
20

four

strokesofthe Otto

cycle

are

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

25

performtheintakeandcompression

strokes,andtheexpansion

cylinderexpansion

pistonstrokes.

The Otto cycle is therefore completed in these twocylinders

12,

14

14,

30,
once

together

perform
per

the

with

its

expansion

crankshaft

16

associatedandexhaustrevolution(360

degrees CA) about crankshaft axis 17.
During the intake stroke, intake air is drawn into
the30

compression

disposedinthecylinder12throughanintakeportcylinder

head

33.

An

inwardly

opening

19(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.
SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

10
Duringpiston20

chargeintothecompression

pressurizes
the

the

air

crossoverstroke,chargepassagetheanddrives(or port)

typically disposed in the cylinder head 33.
5compression

22,

the

air

which

is

This means that.

the compression cylinder 12 and compression piston 20 are asourceofhigh-pressure

gas

to

the

crossoverpassage22,

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

In some embodiments, two or more crossover passages 22

interconnect
10

thecompression

cylinder12 and the

expansion

cylinder 14.
The geometric (or volumetric) compression ratio of15

the compression

cylinder

12

of

for

enginesingeneral)split-cycle

split-cycle
isengine10

hereincommonly(andreferredtoengine.

The geometric (or volumetric) compression ratio of

as

the

"compression

ratio"of thesplit-cycle

the expansion cylinder 14 of split-cycle engine 10(and forsplit-cycle engines in general) is herein commonly referred
to as the "expansion ratio" of the split-cycle engine.
geometric
20

compression

the art as the ratio of the enclosedthecylinderreciprocating25

ratio of a cylinder(including
therein

is

all
at

is

well known in(or trapped) volume inrecesses)

its

when

bottom deadposition to the enclosed volume(i.e.,

the

is

at

for

split-cycle

cylinder

(TDC)

when

position.

definedherein,said

pistonSpecificallythecompressionTheapistoncenter(BDC)

clearance
its

ratio

top

of

a

volume)deadcenterengines

for split-cycle

engines as defined

expansion ratio of an expansion cylinder is30

ascompression

cylinder is determined when the XovrC valve is closed.
specifically

in

Also

herein,thedetermined when

the XovrE valve is closed.
Due to very high compression
1,

30

ratios(e.g.,

to

1,

40

or

greater)withinthecylinder12,an outwardly

opening(opening

outwardly

to1,

SUBSTITUTE SHEET (RULE 26)

20

tocompressionaway

WO 2011/115870

PCT/US2011/028281

11
from

the

cylinder)

valve

24

at

control

5

poppetthe -crossover

flow

from

passage22..

(e.g.,to 1,

30 to 1,

passagecompression
inlet(XovrC)

25

is

used

to

compression

cylinder

12

into

the

Due

high

the

crossover20

crossover

to

very

40 to

1,

expansionor greater)

ratioswithintheexpansion cylinder 14, an outwardly opening poppet crossover
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.
10

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

inpressure(typically 20

thecrossover

26 are timed to -maintainpassage22

bar or higher

at

a

at

full

28

injectshighminimumload)duringall four strokes of the Otto cycle.
At

15

least

one

injector

fuel

into

the pressurized air at the exit end of the crossover passage
22 incorrespondence with the XovrE valve 26 opening,occursshortlydeadcenterbeforeexpansion

position.

The

expansion cylinder
20

fuel

its

14

top

dead

centerdescent

fromits

piston30

air/fuel

reacheschargeits

topentersthewhen expansion

piston 30 isposition.

piston

top deadAs

centerposition,whichclose to30

begins

its

and

while

the

XovrE valve 26 is still open, spark plug 32, which includes
a

spark

plug

tip

39

that

protrudes

intocylinder14,isfired to initiate combustion in the region around the spark
25

plug

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
degrees30

CA pastpreferably,

top

dead

center

(TDC)

combustion can be initiatedpistoniscenter(TDC)

initiated

its

between10

andposition.

through

other

Most

while the expansion

20 degrees

CA pastAdditionally,
ignition

position.

combustion

devices

SUBSTITUTE SHEET (RULE 26)

its

and/or

top deadmaybemethods,

WO 2011/115870

PCT/US2011/028281

12
such

as

with

glow

plugs,

microwave

ignitiondevicesor

exhaust

gases

are

through compression ignition methods.
Duringtheexhauststroke,pumped out of the expansion cylinder 14 through exhaust port
5

35 disposed in cylinder head 33.
exhaust valve 34,
port 35,

disposed in

An inwardly opening poppet

the inlet 31 of the exhaust

controls fluid communication between the expansion

cylinder 14 and the exhaust port 35.
and the exhaust
10

passage 22.

port

35 are

The exhaust valve 34

separatefrom the crossoverThat is, exhaust valve 34 and the exhaust port

35 do not makecontact with,or are notdisposed in,thecrossover passage 22.
With the split-cycle engine concept, the geometricengine15

parameters

length,bore,

stroke,connecting

rodcompression

ratio,

etc.)

the

expansion

cylindersarevolumetriccompression

12

and

14

of

generally

independent from one another.

For example, the crank throws

36,

cylinder38forcylinder 14,
20(i.e.,

thecompression

respectively,

12

and

expansion

may have different radii and may

be phased apart from one another such that top dead center(TDC) of the expansion piston 30 occurs prior to TDC of thecompression piston 20.
cycle

engine10This independence enables the split

to potentially achieve

higherefficiency

levels and greater torques than typical four-stroke engines.
25

The geometric independence of engine parameters inthe split-cycle

engine 10isalso one of the main reasons

why pressure can be maintained inas discussed earlier.
reaches
30

its

top

the crossover passage 22

Specifically, the expansion piston 30

deadcenterposition

prior

to

the

compression piston reaching its top dead center position bya discreet phaseangle(typically between

angle

This

phase

degrees).

angle,

10 and 30 crank

togetherwith proper

timing of the XovrC valve 24 and the XovrE valve 26, enables
SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

13
enginesplit-cycle

the

to

10

pressuremaintaincrossover passage 22 at a high minimum pressure

the

in

(typically

20 bar absolute or higher during full load operation) duringThat is, theall four strokes of its pressure/volume cycle.
5split-cycle engine 10 is operable to time the XovrC valve 24
and the XovrE valve 26 such that the XovrC and XovrE valves

are both open for a substantial period of time (or period of
crankshaft
descends
10

therotation)from its

compression

duringwhich

the

TDC position towards
piston20

26(or crankshaft

are

both

transferred

15

(1)

a

from

the

the

expansion

period,fromcylinderthe pressure

dropping(typically 20,

in

mass

of

cylinderthe crossover

12

passagethepressure

30,

40

bar

duringabsoluteduring a substantial(typically 80% of the24

andentireXovrE

thisprevented

minimum

valve

into

is

is

predetermined

XovrC

air

duringaenginetheits

During the period of

Accordingly,-

14.

Moreover,greater),

fromfrom the crossover passage 22

operation).
cycle

ascends

below
or

30

BDC position andequal

compression(2)

pistonthat the crossover valves 24,

substantiallycrossover passage 22 andto20

rotation)

open,

its

simultaneously

BDC position towards its TDC position.
time

expansion

full

load

portion oftheengine

or

valve

26

cycle
are

both

closed to maintain the mass of trapped gas in the crossover
passage 22 at a substantially constant level.
25

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

minimumpressureduringallfourstrokesofmethodofhavingthethe engine's pressure/volume cycle.
For

purposesherein,the

XovrC 24 and XovrE 26 valves open while the expansion piston
30

30 is

descending from TDC and the compression

ascending toward TDC in
substantially

equal

order

mass

crossover passage 22 isoftopiston 20 issimultaneously

gas

into

and

transfer

out

of

a

the

referred to herein as the Push-Pull

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

14method of gas transfer.
the pressure

enablesisIt

in thePush-Pull method thatthecrossover passage 22of thesplit-cycle engine 10 to be maintained at typically 20 bar
or higher during all four strokes of the engine's cycle when5

the engine is operating at full load.
As

discussed

earlier,theexhaustdisposedinthe exhaust

port

of

the

cylinderseparatefrom thepassage

22.

The

arrangement10of the exhaust valve

34

is

head

33

structural

34 not being disposed inand therefore the exhaust port 35

the crossover passage 22,
notsharing any common portion with the crossover passage

22,

is

preferred

gas ininorder to maintainthe trapped mass ofthe crossover passage 22 during the exhaust stroke.

Accordingly,
15

crossover

35

valve

large

cyclic drops

inpressureareprevented

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

20

piston 30

reaches

time,pressure

theits

top dead center
ratio

of

the

position.

pressure

At thisincrossoverpassage 22 to the pressure in expansion cylinder 14 is high,due to the fact that the minimum pressure inpassageistypically 20

barabsoluteorthe crossoverhigherandthepressure in the expansion cylinder during the exhaust stroke
is typically about one to two bar absolute.
25

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

issubstantially

cylinder 14
This

high

and/or30

In other words,

higher(typically inpressure

fuelchargehigh speeds.

ratio
to

than the pressurecausesinitialflow

flow into expansion

of

the

cylinder

14

air
at

These high flow speeds can reach the speed ofparticularly

because it

expansion

the order of 20 to 1 or greater)sound, which is referred to as sonic flow.
isincausesadvantageoustoThis sonic flow

split-cycle

a rapid combustion

event,SUBSTITUTE SHEET (RULE 26)

enginewhich

10enablesWO 2011/115870

PCT/US2011/028281

15
thesplit-cycle

engine10thoughignition

expansion piston 30 isdescending

pressures

even

to

maintainishighcombustion

initiatedfrom its

while

the

top dead center

position.
5

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

40,

which isoperatively connectedto the crossover passage 22 by an air reservoir
42.

(tank) valve

Embodiments with two or more crossover passages 22 may

include a tank valve 42 for each crossover passage 22, which
10

connect 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

15

reservoir(tank)

port

44,

which

passage

22

to

air

tank

40.

dividedinto a first

and

a

first

second
air

the

air

air

extends
The

reservoir

reservoirtank port section(tank)

airfromcrossovertank port(tank) port
port

44

is

section

46

48.

The

section46 connects the airtank valve

42 to the crossover passage 22, and the second air tank port
20

section 48 connects
40.

The

includesvolumethethe air tank valveofvolume

the
of

first
all

air

42 to thetankadditional

port

ports

air

tank

sectionand46

recesses

which connect the tank valve .42 to the crossover passage 22
when the tank valve 42 is closed.
25

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(e.g.,

pneumatic,

Additionally,30

activated by various valve actuation devices

system with

the
two

hydraulic,cam,tank valve

42 may compriseor morevalveselectric

actuated

or
a

with

the

like).

tank valve
two

or moreactuation devices.
Air

tank

40

is

utilized

to

store

energyintheform of compressed air and to later use that compressed air

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

16
to

power

the

crankshaft

16,

as

described

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

5

et al.

This mechanical means for storing potential energy

providesnumerous

potential

state of the art.

advantages

For instance,overcurrent

the split-cycle engine 10

can potentially provide many advantages

in

fuel

gains

at

relatively

and

NOx

emissions

reduction

manufacturing and waste disposal costs intechnologies
10

the

on

the

market,such

asefficiency
lowrelation to otherdieselengines

andelectric-hybrid systems.
Byclosingofselectively
the

air

controllingtank valve

42

the

and

opening

thereby

and/orcontrolling

communication of the air tank 40 with the crossover passage
22,
15

the split-cycle

Engine Firing(EF)

air-hybrid engine
mode,

10 is

an Air Expander

operablean(AE) mode, an Air

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

in(AEF) mode,

The EF mode is a non

hybrid mode in which the engine operates as described above

20

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

25

40

without

combustion

cylinder14(i.e.,

utilizingthekinetic

engine10duringnooccurring

fuel

the

expenditure),

energybraking.

in

of

The

expansion

such

as

by

a. vehicle

including

the

FC

an

mode

is

air-hybrid

operating mode in which excess compressed air not needed for
combustion

is

than

enginefull

storedload

at constant speed).
30

mode

has

an

in

the
(e.g.,

airtankengine

40,

such

idle,

as

vehicleat

lesscruising

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

therefore,itisdesirable to have a net gain when the compressed air is usedata laterusage modes.

time.

The AEand AEF modes

arestored energy

The AE mode is an air-hybrid operating mode in

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

17which compressed air stored in

the air tank 40 isdrive the expansion piston 30 without combustion5

inthe expansion

cylinder

The

AEF

an

mode

is

14

(i.e.,

air-hybrid

used tooccurringno fuel expenditure).

operating

mode

in

which

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

12

is

the AE and AEF modes,

preferably

deactivated

reduce pumping work10

thecompression

the compression cylinder

to minimizeorsubstantially(in terms of negative IMEP) performed bypiston20

onintake

air.

As

will

be

discussed in further detail herein, the most efficient way todeactivate

the compression

cylinder12 isto keep the XovrC

valve 24 closed through the entire rotation of the crankshaft
16,
15

and ideally to keep the intake valve 18 open through theentire rotation of the crankshaft.
In

engineoutwardly opening,20

the entire

rotation

embodimentillustrates

embodiments

where

the

intakevalve

isthe intake valve may be kept open throughof crankshaft.

However,the more typicalthisexemplary

configuration

the intake valve 18 is inwardly opening.

where

Therefore, in order

to avoid compression piston 20 to intake valve 18 contact at
the top of the compression piston's stroke,

the intake valve

18 must be closed prior to when the ascending piston 20 makes
contact with the inwardly opening valve 18.
Additionally,25
trappedair

intake

valve

is

not

closingorder to avoid
Generally,30

isimportant

to

too

from

compressedtoexcessive

TDC

of

much

insure
the

that

the

angle

of

in

the

compression

pistontemperatureand pressurebuild-up.

this means that the residual compression ratio at

the point of
less,

it

intakeand more

valve

18

closing should be 20

preferably

10

to

1

or

less.

In

to 1

or

exemplaryengine 10, the residual compression ratio will be about 20 to
1 at an intake valve 18 closing angle(position) of about 60

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

18
CA degrees before
intakevalve

TDC of the compression

closing

is

60

CA

degreespiston 20.
before

When

TDC,

it

is

highly desirable (as discussed in greater detail herein) that
intake valve opening be 60 CA degrees after TDC.
5

Accordingly, in order to deactivate the compression
cylinder 12 without excessive build-up of air temperature andpressure,itispreferable

open through at least 240
crankshaft
10

16.

intake~valveofthethe intake

valve 18 be kept

CA degrees of the rotation of theMoreover,

it

is

more

preferable

that

the

18 be kept open through at least 270 CA degrees

rotation

preferable

that

that

of

the

the

crankshaft

16,

and

intake

valve

kept

open

be

it

is

most

throughat

least 300 CA degrees of rotation of the crankshaft 16.

15

As

the

responsetoavoiding

contact,

aircompression

occur

as

20

20

valve

18

compressionisclosedsolelyinpiston

20

valve

18

(and therefore

ascends

negativetoward

top

dead

will

centertherefore

to reopen the intake valve 18 at a timing

when the pressure in the compression cylinder 12 is equal tothe pressureindifferential

betweentheopening

the intake port 19
the(i.e.,

compression

timingoftheintakewhen the pressure
cylindertop

However,indeadcenterpractice,during the compression

valvecylindercrown,

and

the

would

be

intake valve

18

the

compression

after

the

intakevalve

piston18

20.

closesstroke of the compression piston 20,
inthe compression cylinder

12

Some of the heat generated is lost to thecomponents

and the18ofthe pressure and temperature
begins to rise.

12

In an ideal system,

symmetrical with the closing timing of the
about

30

its

work)

In order to maximize efficiency, a primaryintake port 19 is substantially zero).

25

to(TDC) .

position

aim ispistonintakesuch

cylinderas the cylinder
head.

Therefore,

walls,

the piston

the pressure

inthe compression cylinder 12 and intake port 19 is equalized

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

19
at a slightly earlier timing(relative to top dead center)on the intake stroke of the compression piston 20 than on
the compression stroke.
intake5Inaddition,wave

effects inport 19 and the flow characteristics

valve 18 (such as the fact that flow is
low valve lifts)

result in

theof the intake

quite restricted at

the optimum closing and opening

timing of the intake valve 18 deviating slightly from truly
symmetrical about top dead center.
Therefore,
10

it

is

important

to

keep

the

closing

position (timing) and opening position (timing) of valve 18
substantially(i.e.,

symmetrical withwithin plus

or minus

10

respect to TDC of piston 20,

CA degrees)inorder toreturn as much of the compression work to the crankshaft 16
as possible.
15

For example, if the intake valve 18 is closed

at substantially 25 CA degrees before TDC of the compression
piston20 tovalve 18

avoid being hit

by the piston

should open at substantially

TDC of piston 20.

20,

then the25 CA degrees after

In this way, the compressed air will act

as an air spring and return most of the compression work to20

the crankshaft 16 as the air expands and pushes down on thecompression piston 20 when the piston 20 descends away from
TDC.

Accordingly,inorder to avoid compression piston

20 to valve 18 contact and to reverse as much compression
25

work aspossible,itopening

positions(timing) ofispreferable

that

valve

18

the closing
are

and

symmetrical,

within plus or minus 10 CA degrees, about TDC of compression
piston 20
before30

degrees(e.g.,

TDC,

if

then

after

it

TDC

intake valve 18 closes at 25 CA degrees
must

of

open

piston

at

25

20).

plus

or minus

However,

it

10

is

CA

more

preferable if the closing and opening positions of valve 18
aresymmetrical,

TDC

of piston

within20,

plus

or minus

5 CA

and most

preferable

if

SUBSTITUTE SHEET (RULE 26)

degrees,
the

about

closingandWO 2011/115870

PCT/US2011/028281

20
within plus

opening positions of valve 18 are symmetrical,
or minus 2 CA degrees, about TDC of piston 20.
Also,

in

the AE and AEF modes,

the air tank valve

42 is preferably kept open through the entire rotation of the5

crankshaft

16(i.e.,

the air tank valve 42 is

kept open atleast during the entire expansion stroke and exhaust' strokeof the expansion piston).
tank 40 isCompressed air stored in

the air

released from the air tank 40 into the crossover

passage 22 to provide charge air for the expansion cylinder
10

14.

In the AE mode, compressed air from the air tank 40 isadmitted to the expansion cylinder 14,
anexpansion

stroke.

expansion stroke

The

air

of the expansion

power to the crankshaft 16.
15

In

the exhaust stroke.
the air tank 40 is
with

fuel

at

is

at the beginning of

expandedonpiston 30,

the

same

transmitting

The air is then discharged on

the AEF mode,

admitted

the beginningcompressed

air fromto the expansion cylinder

14

of

The

an expansion

stroke.

air/fuel mixture ,is ignited, burned and expanded on the same
expansion
20

power

stroketo theof thecrankshaft

expansion

piston 30,

transmitting

16.

combustion

products

The

arethen discharged on the exhaust stroke.
As

shown

XovrCstdIntstd,
negative IMEP)
25

valve

in

FIG.

2

graph

the greatest pumping losses

occur inoperated with(e.g., the timing used for the EF mode).
in

this

arrangement

Therefore,itdeactivation
30

is

is

(in

the AE and AEF modes if

and intake valve are
also

increaseapparent

that

necessary

tolabeled:terms ofthe XovrC

standard timing

The pumping losses
withenginecompression

minimizeor

speed.
cylindersubstantiallyreduce pumping work performed by the compression piston.
Referring

to

FIG.

2

XovrCopenIntclsd,

thepumping

losses

XovrC

valve

is

kept

open

and

the

graph
are reduced

intakeSUBSTITUTE SHEET (RULE 26)

valvelabeled:
if

the

is

kept

WO 2011/115870

PCT/US2011/028281

21
closed.

In this arrangement,in compressed

airfrom theintake stroke and pushes
passage during the5duringthethis air back into the crossover
No ambient

intakeair enters the compression cylinder.
to

FIG.

2

graph

labeled:

XovrCclsdIntclsd,

the pumping losses are further reduced

if both

the

XovrC

valve

closed.

In

thisarrangement,

compression

cylinderdecompressed by

the

and

is

the

intakevalve

airpresent

thecyclicallycompression piston

are

kept

in

the

compressedandin theform ofalarge air spring.

However, the geometric compression ratiosof the compression

cylinder(e.g.,
15

crossover passage

compression stroke.

Referring10

the compression piston draws

inexcesscompression.of 40

to

is

lost

work

12 and piston 20 are very high1) .

Accordingly,

to

an

much

excessive

of

the

heat

of

compression.
Referring

20

FIG.

2

XovrC clsdInt std,thefurther if

the XovrC

valve is

kept

valve

operated

withstandardispumpingarrangement,

thecommunication

with the intake port

of

the

compression

compression

compression
25

tocylinderpiston,isgraphlossesarereducedclosed while thetiming.

cylinderandlabeled:

is

air

this

in

fluid

intakepresent

compressed duringintakeInduring the

the

even

stroke

in

the

the

compression

graphlabeled:piston's compression stroke.
Referring
XovrCclsd_Int_open,.

to

FIG.

as

discussed

2

earlier,thepumping

losses are the lowest if the XovrC valve is kept closed andthe30

intake

valve

is

kept

open.

compression piston draws induring its

intakeInthisintake air

stroke and pushes

arrangement,from the intake port
the air

intake port during its compression stroke.
of compression

work is

done

since

the

the

back

A minimum amountintakeSUBSTITUTE SHEET (RULE 26)

into the

valve

18

is

C:\NRPortb\DCC\CAB\4551180_1.DOC-20A)8/2012-22

closedonly

inpiston20.

Additionally,

responsetoavoiding

mostofcontact

that

with

compression

compression

work

is

reversible when the opening and closing timings of intake valve 18
are5

substantiallysymmetrical

relativeto

TDC ofthecompression

piston 20.
Although the invention has been described by referencetoaspecificchanges

embodiment,

should be

may be made within theconcepts described.
10

itspiritAccordingly,

understoodand scope
it

is

that

numerousof theinventive

intended

invention not be limited to the described embodiment,
have

the

full

scope

definedThe

referencebythelanguage

of

that

the

but thatitthefollowingclaims.

publication

15

is

which

(or

in

information

known,

isthisderivednot,andor admission or

acknowledgement

specification

to

any

prior

from

any

mattershould
any

it),

or

to

not

be

taken

suggestion

form ofpart

ofgeneralcommontheknowledge

that

an
that

or known matter

prior publication (or information derived from it)
forms

as,

field

of

in

the

the

claims

which

the

word

endeavour to which this specification relates.

20

Throughout
follow,"comprise",
will beandofspecification

such

as

or

steps

otherwise,"comprises"

to imply the inclusion
integers

andrequirescontext

variations

understoodstep or group

25

the

unlessthisof abut not

theor"comprising",

statedinteger

exclusionother integer or step or group of integers or steps.

orof anyWO 2011/115870

PCT/US2011/028281

23
CLAIMS

What is claimed is:
1.
5

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

cylindercrankshaft

such

that

slidably received within aandoperatively

thecompression

connected
pistontothereciprocatesthrough an intake stroke and a compression stroke during a10

single rotation of the crankshaft;an intake valve selectively controlling

air flow

into the compression cylinder;
an
15

expansion

expansion

cylindercrankshaft

suchpiston

and

that

the

slidablyreceived

withinanoperatively

connected

totheexpansion

pistonreciprocatesthrough an expansion stroke and an exhaust stroke during asingle rotation of the crankshaft;a20

crossoverpassageinterconnecting

compression

and expansion

cylinders,the crossover passage

including ,acrossovercrossover

expansion

compression(XovrE)

valve

the

(XovrC)

valve

and

definingapressureachamber 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;
the engine being operable in

30

an Air Expander(AE)

mode and an Air Expander and Firing (AEF) mode, wherein, in
the AE and AEF modes, the XovrC valve is kept closed during
an entire rotation of the crankshaft,and the intake valve

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

24
is

kept

open

for

at

least

240

CA

degrees

of

the

same

rotation of the crankshaft.
2.

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

wherein, in the AE and AEF modes,
5

the intake valve is

kept

open for at least 270 CA degrees of the same rotation of the
crankshaft.
3.

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

wherein, in the AE and AEF modes,

the intake valve is

kept

open for at least 300 CA degrees of the same rotation of the10

crankshaft.
4.

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

wherein,

in

the

ratio

an

intake

at

AE

and

AEF modes,

valveclosingaresidualpositioniscompression
20

to

1

or

less.
15

5.

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

wherein,

in

the

ratio

an

intakeat

AE

and AEF modes,
valveclosingaresidualpositioniscompression
10

to

I or

less.
6.
20

wherein,in

The split-cycle air-hybrid engine of claim 1,
the AE and AEF modes,

theintake valve closing

position and intake valve opening position are symmetrical,
within

plus

or

minus

10

CA

degrees,

about

the

top

dead

center position of the compression piston.
7.
25

wherein,in

The split-cycle air-hybrid engine of claim 1,
the AE and AEF modes,

the intake valve closing

position and intake valve opening position are symmetrical,
within plus or minus 5 CA degrees, about the top dead center
position of the compression piston.
8.
30

wherein,in

The split-cycle air-hybrid engine of claim 1,
the AE and AEF modes,

the intake valve closing

position and intake valve opening position are symmetrical,
within plus or minus 2 CA degrees, about the top dead center
position of the compression piston.

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US2011/028281

25
9.
wherein,in

The split-cycle air-hybrid engine of claim 1,
the AE and AEF modes,

the intake valve is

kept

open during the entire same rotation of the crankshaft.
10.
5

wherein,in

The split-cycle air-hybrid engine of claim 1,
the AE mode, the air reservoir valve is open,

and compressed air from the air reservoir is admitted to the
expansion cylinder, at the beginning of an expansion stroke,
the air is expanded on the same expansion stroke of the
expansion piston,
10transmitting power to the crankshaft,andthe air is discharged on the exhaust stroke.
11.
wherein,

The split-cycle air-hybrid engine of claim 1,
the AEF mode, the air reservoir valve is open,inand compressed air from the air reservoir is admitted to the15

expansion

cylinderexpansion

stroke,

the

same

with

which isexpansiontransmitting

power tofuel,ignited,stroke
the

at
of

the

beginningofanburned and expanded ontheexpansion

crankshaft,and thepiston,combustion

products are discharged on the exhaust stroke.
12.
20

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

cylinder
such

that

slidablyandoperatively

thecompression

received within aconnected
pistonto *thereciprocatesthrough an intake stroke and a compression stroke during a25

single rotation of the crankshaft;an intakevalve selectively

controlling

air

flow

from an intake port into the compression cylinder;
an expansion piston
30

expansion

cylindercrankshaft

such

that

and
the

slidablyreceived within an

operatively
expansionconnected
pistontothereciprocatesthrough an expansion stroke and an exhaust stroke during asingle rotation of the crankshaft;

SUBSTITUTE SHEET (RULE 26)

WO 2011/115870

PCT/US20111/028281

26acrossovercompression

5

andexpansion

includingacrossover

expansionpassageinterconnecting

cylinders,thecompression

crossover(XovrE)thecrossover passage(XovrC)

valve

and

definingapressurevalveachamber therebetween;ancrossoverairreservoir

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

10

flow into and out of the air reservoir;
the engine being operable inmode and an Air Expander and Firing

an Air Expander(AE)(AEF) mode, wherein, in

the AE and AEF modes, the XovrC valve is kept closed during
15

an entire rotationof the crankshaft,and theintake valve

is opened at a position at which pressure in the compression
cylinderisapproximately

equal

to pressure

in

the

intake

port.
13.
20

A

methodofoperatingasplit-cycle

airhybrid engine including:a crankshaft rotatable about a crankshaft axis;acompression
crankshaft

25

slidablyreceived

withinandoperatively

connected

tothecompression

compression
cylinder
such

that

pistonthrough an intake stroke

pistonand a compressionathereciprocatesstroke during asingle rotation of the crankshaft;anintakevalve

selectively

controlling

air

flow

received

withinanconnected

totheinto the compression cylinder;
an30

expansion

expansion

cylindercrankshaft

such

and

that

through an expansion

pistontheslidably

operatively
expansion

pistonstroke and an exhaust

single rotation of the crankshaft;

SUBSTITUTE SHEET (RULE 26)

reciprocatesstroke during a

WO 2011/115870

PCT/US2011/028281

27acrossovercompression and expansion

5

includingacrossover

expansion

crossoverpassageinterconnecting

cylinders,the crossover passage

compression(XovrE)the(XovrC)

valve

and

definingapressurevalveachamber therebetween;ancrossoverairreservoir

passageandoperatively

selectively

connected

operable

to

to

the
store

compressed air from the compression cylinder and to delivercompressed air to the expansion cylinder; and10

an air reservoir valve selectively controlling air
flow into and out of the air reservoir;
the engine being operable inan Air Expander(AE)

mode and an Air Expander and Firing (AEF) mode;the method including the steps of:
keeping the15

XovrC valve closed

during an entire

rotation of the crankshaft; andkeeping the intake valve open during at least 240
CA degrees of the same rotation of the crankshaft;whereby the compression cylinder is deactivated to20

reduce pumping work performed by the compression piston on
intake air.
14.
keepingtheThe method of claim 13, including the step ofintakevalve

closing

positionvalve opening position symmetrical,
25

CA

degrees,

about

the

top

and theintakewithin plus or minus

deadcenterposition

of

5

the

compression piston.
keeping

15.

The method of claim 13, including the step oftheintake

valve

open

duringtheentiresamerotation of the crankshaft.
30

16.

The method of claim 13, including the step ofclosing the intake valve
ratio at thesuch thataresidualintake. valve closing position

less.
SUBSTITUTE SHEET (RULE 26)

iscompression20

to 1 orWO 2011/115870

PCT/US20111/028281

28The method of claim 13,

17.

further including thesteps of:opening the air reservoir valve; andoperating the engine
5compressed

air

from

the

in

air

the AE mode

reservoir

toby admitting
theexpansion

cylinder, at the beginning of an expansion stroke, expanding
the

air

on

piston,thesameexpansiontransmitting

powerstroke

to

of

the

the

expansion

crankshaft,anddischarging the air on the exhaust stroke.
1018.

The method of claim 13, further including thesteps of:opening the air reservoir valve; andoperating the engine in the AEF mode by admitting
compressed
15

air

from

the

air

reservoir

totheexpansion

cylinder with fuel, at the beginning of an expansion stroke,
which isstrokeignited,ofcrankshaft,

the
and

burned and expanded on the same expansion

expansion

piston,discharging

thetransmitting
combustion

exhaust stroke.

SUBSTITUTE SHEET (RULE 26)

power

products

totheon the