(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)

Beach Green, Shoreham-by-Sea, West Sussex BN43 5YE(GB).

(51) International Patent Classification:
F02B 33122 (2006.01)(21) International Application Number:
PCT/US20ll/028285(22) International Filing Date:
14 March 2011 (14.03.2011)(25) Filing Language:

English(26) Publication Language:

English(30) Priority Data:
61/313,831
61/363,825
61/365,343

15 March 2010 (15.03.2010)13 July2010 (13.07.2010)18 July2010 (18.07.2010)

us
us
us

(71) Applicant (for all designated States except US): SCUDERI GROUP, LLC [US/US]; 1111 Elm Street, Suite 33,
West Springfield, MA 01089 (US).
(72) Inventors: MELDOLESI, Riccardo; 55 New Road,
Shoreham-by-Sea, West Sussex BN43 6RB (GB).
BADAIN, Nicholas; 37 Rosslyn Road, Shoreham-by-Sea,
West Sussex BN43 6WL (GB). GILBERT, Ian; 67=

WO 2011/115873 A1

PCT(74) Agents: FILDES, Christopher, J. et al.; Fildes & Outland, P.C., 20916 Mack 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,
CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO,
DZ, EC, EE, EG, ES, FI, 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, VA, UG, US, UZ, VC, VN, ZA, ZM, ZW.
(84) 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,
TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK,[Continued on next page];;;;;;;;;;;;;;; (54) Title: SPLIT -CYCLE AIR-HYBRID ENGINE WITH AIR TANK VALVE---;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

FIG. 1(57) Abstract: A split-cycle air-hybrid engine includes a rotatablecrankshaft. A compression piston is slidably received within a compression cylinder. An expansion piston is slidably received within an
expansion cylinder. A crossover passage interconnects the compression
and expansion cylinders. The crossover passage includes a crossovercompression (XovrC) valve and a crossover expansion (XovrE) valve.
An air reservoir is operatively connected to the crossover passage. An
air reservoir valve selectively controls air flow into and out of the air
reservoir. In an Engine Firing (EF) mode, the air reservoir valve is kept
closed. In an Air Expander (AE) and an Air Expander and Firing(AEF) mode, the air reservoir valve is kept open for a duration that is
at least as long as a duration of the XovrE valve opening event. In an
Air Compressor (AC) mode and a Firing and Charging (FC) mode, theair reservoir valve is selectively opened and closed.

W 0 2011/115873 A 1 11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, Published:
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, with international search report (Art. 21(3))
GW, ML, MR, NE, SN, TD, TG).

wo 2011/115873

PCT/US2011/028285

SPLIT-CYCLE AIR-HYBRID ENGINE WITH AIR TANK VALVETECHNICAL 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

intakecompression,

expansion

cycle(i.e.,

the(or power)(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

purposes

definition is offered forofclarity,thefollowing

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;

SUBSTITUTE SHEET (RULE 26)

wo 2011/115873

PCT/US2011/028285

2anwithinan

expansion

expansion(power)cylinder andthe crankshaft such thatreceived

operatively connectedtoand~ anexhaust stroke during asingle rotation of the crankshaft; andacrossoverpassage(port)

compression and expansion cylinders,
including

at

least

disposed therein,
10

slidably

the expansion piston reciprocatesthrough an expansion stroke
5pistoncompressionacrossoverinterconnecting

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.
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

andcombineasplit-

variouscontrols.

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

pistonslidablyreceived

withinandoperatively

connected

tothecompression

pistonathe

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

SUBSTITUTE SHEET (RULE 26)

wo 2011/115873

PCT/US2011/028285

3anwithinan

expansion

expansion

the crankshaft(power)cylindersuch that

pistonandslidably

operatively

received

connected

the expansion piston

toreciprocatesthrough an expansion stroke and an exhaust stroke during a5single rotation of the crankshaft;acrossoverpassage(port)

compression and expansion cylinders,
including

at

least

disposed therein,
10

compressionacrossoverinterconnecting
thecrossover

expansionthepassage(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 States
8,

20

Patent2008 to Scuderi et al.,No.

7, 353,786 granted April

which is incorporated herein byreference,contains an extensive discussion of

air-hybrid

andsimilar-type

patent discloses

detailsofengines.
prior

Inhybridsplit-cycle

addition,

systems

this

of

which

run

in

the present disclosure details further developments.
A split-cycle air-hybrid engine
normal operating or firing
the25

Enginemodes.

Firing

(EF)

mode)

In the EF mode,

reservoir.

connecting

In

the

the

mode
and

the engine

hybrid split-cycle engine,
air

(NF)

be

a

(also commonly called
four

basic

functions

air-hybrid

as a

non-air

operating without the use of its

EF mode,crossovercanapassage

tank
to

valve

the

operatively

airreservoir

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:

SUBSTITUTE SHEET (RULE 26)

with

The fourwo 2011/115873

PCT/US2011/028285

4

1)

Air

Expandercompressed

(AE)

air

mode,

energy

which

from

includes

the

air

using

reservoir

without combustion;
2)
5

Air Compressor(AC)compressedenergy

air

mode,

which

into

includesthe

airstoring

reservoir

without combustion;
3)

Air Expander and firing(AEf) mode, which includes

using compressed air energy from the air reservoir
with combustion; and10

Firing4)

andstoring

Charging

compressed

(FC)
air

mode,

which

includesenergy

into

the

air

AE,

AC,

reservoir with combustion.

15

However,further

AEF andfC,

optimization ofis desirable

these modes,EF,to enhance efficiency andreduceemissions.

SUMMARY OF THE INVENTION

The present invention provides a split-cycle air20

hybrid engine in which

the use of the Engine

the

the

Air

Expander(AE),

Expander and Firing(AEF),

Air

Compressor

firing
(AC),

(EF),

the

Air

and the Firing and Charging(FC)

modes are optimized for potentially any vehicle in any drive
cycle for improved efficiency.
25

More

particularly,

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

A compression piston iscompression
30

crankshaft

cylinder
such

that

slidablyandoperatively

thecompression

received within aconnected

pistontothereciprocatesthrough an intake stroke and a compression stroke during asingle rotation of the crankshaft.
slidablyreceived

withinan

An expansion piston is
expansion

SUBSTITUTE SHEET (RULE 26)

cylinderandwo 2011/115873

PCT/US2011/028285

5
operatively
expansion
andanconnected

pistonexhaustcrankshaft.
5

tothroughreciprocatesstrokeA

crankshaft

theduring

a

an

that

the

expansion

strokerotationoftheinterconnects

thesinglepassagecrossoversuchcompression 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.

reservoir valve selectively controls air flowof the air reservoir.

An airinto and out

The engine is operable in one or moreof an Engine Firing (EF) mode, an Air Expander (AE) mode, an
15

Air Compressor
mode,
the

(AC)

mode,

an Air Expander and Firing

and a Firing and Charging

airreservoir

valve

is

(FC)

kept

rotation of the crankshaft.

mode.

closed(AEF)

In the EF mode,
duringtheentireIn the AE and AEF modes,

the'air reservoir valve is kept open for a duration that is at
20

least

as

event.

long

as

a

durationofIn the AC and FC modes,

selectively opened and

the

XovrE

valve

opening

the air reservoir valve isclosed duringasinglerotationofthe crankshaft.
A method25ofoperatingengine 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
cylinder
that
30

and

operatively

connected

the compression piston

to

the

reciprocates

crankshaft

suchthrough an intake

stroke and a compression stroke during a single rotation ofthecrankshaft.

withinanAnexpansion

expansion piston
cylinderandisslidably

operatively

the crankshaft such that the expansion piston

SUBSTITUTE SHEET (RULE 26)

received

connected

toreciprocateswo 2011/115873

PCT/US2011/028285

6
through an expansion stroke and an exhaust stroke during asinglerotationofthecrankshaft.

A crossover

passageinterconnects the compression and expansion cylinders.
crossover passage
5

valve

and

pressure

10

15

a

includes acrossoverchamber

expansion(XovrE)

therebetween.

operatively

connected

selectively

operablecompression

cylinder andexpansion

crossover compressiontotocylinder.

An

air

the

crossoverstore

compressed

to deliver

An

valve

air

definingareservoirispassage

and

air

from

valve

the

to

the

selectively

controls air flow

into and out of the air reservoir.

The

engine is

ope~ablein one or more of an Engine firing

(EF)

mode,

an

Air

mode,

an Air Expander and Firing

and Charging

Expander

( FC)

(AE)

mode.

mode,

an

Air

(AEf)

Compressor

mode,

and a

mode,
entirekeepingtherotationreservoir;

in

air

of
the

(AC)

Firing

The method in accordance with thepresent invention includes the following steps:

20(XovrC)

compressed air

reservoirThe

reservoir

the
AE

valve

crankshaft
and

AEF

closedin the EF
duringthetoisolatetheairmodes,

keepingtheairreservoir valve open for a duration that is at least as longas a duration of the XovrE valve opening event to allow foruse of stored compressed air;selectively

openingandrc modes,and in the AC andclosingtheairreservoir

valve

during a single rotation of the crankshaft to allow for flow
25ofcompressed

air

into

the

air

reservoirforstorageofcompressed air.
These
invention will

and

other

be morefeatures

fully

and

understoodadvantages
from

the

of

the

followingdetailed description of the invention taken together with the30

accompanying drawings.

SUBSTITUTE SHEET (RULE 26)

wo 2011/115873

PCT/US2011/028285

7
BRIEF DESCRIPTION OF THE DRAWINGSIn the drawings:
FIG.
5

1 is a lateral sectional view of an exemplary

split-cycle air-hybrid engine in accordance with the present
invention;
FIG.

2 is a lateral view of an exemplary air tankvalve of the split-cycle air-hybrid engine; andFIG.
10

3 is a perspective view of the air tank valveof FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

The following glossary of acronyms and definitions
15of terms used herein is provided for reference.
In General
Unless otherwise specified,closing timings

are measured

all valve opening andin crank angle degrees

after

top dead center of the expansion piston (ATDCe).
20

Unlessotherwise

specified,

all

valve

durations

are in crank angle degrees (CA) .
Air tank(or air storage tank):

Storage tank for compressed

air.
ATDCe: After top dead center of the expansion piston.
25

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

The

compression

cylinderandits

associatedits

associatedcompression piston of a split-cycle engine.
Expander:.

The

expansion

cylinderandexpansion piston of a split-cycle engine.
30

Flow control valve (s):Device (s)inserted into the pipework

which can control the flow in that pipework.
Reedvalve:

elementis

A pressureaflexible

activated
plate

valve

which

where

seals

SUBSTITUTE SHEET (RULE 26)

theagainstcontrolafixedwo 2011/115873

PCT/US2011/028285

8housingandblocksflow

pressure builds

up on

plate

and

deflects

in

the

a

forwardreverseopens,

direction.

side ofallowing

flow

the
in

When

plate,
thethereversedirection.
5

Tank

valve:

Valve

connecting

the

Xovr

passagewith

thecompressed air storage tank.
VVA:

Variable

operable

to

valve

alter

actuation.

A

shape

timingtheormechanism
of

a

or

methodvalve's

lift

profile.
10

Xovr

(or

Xover)

valve,

passage

or

port:

The

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

cylindersthrough

which

gas

flows

from

compression to expansion cylinder.
XovrC
15

(or XoverC)

valves:Valves at

the compressor end of

the Xovr passage.
XovrE(or XoverE)

valves: Valves at the expander end of thecrossover (Xovr) passage.
Referring to FIG. 1, an exemplary split-cycle airhybrid engine is shown generally by numeral 10.
20

The split-

cycle air-hybrid engine 10 replaces two adjacent cylindersofaconventional

enginecompression cylinder

with

a

combinationof

12 and one expansion cylinder 14.

oneAcylinder head 33 is typically disposed over an open end of
the expansion and compression cylinders 12,25

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
cylinder 12, together with its associated compression piston
20,
30

performtheintakeandcompression

strokes,andtheexpansion

cylinderexpansion

pistonstrokes.

The Otto cycle is therefore completed in these two

30,

14,

together

perform

the

with

its

expansion

SUBSTITUTE SHEET (RULE 26)

associatedandexhaustwo 2011/115873

PCT/US2011/028285

9cylinders

12,

14

once

per

crankshaft

16

revolution(360

degrees CA) about crankshaft axis 17.
During the intake stroke, intake air is drawn intothe5

compression

disposedincylinder12throughanintakeportcylinder

head

33.

An

inwardly

openingthe19(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.
During10piston20

chargeintothecompression

pressurizes
the

the

crossoverairstroke,chargepassage

and

(or

the

drivesport)

typically disposed in the cylinder head 33.

compression

22,

the

air

which

is

This means thatthe compression cylinder 12 and compression piston 20 are asource15ofhigh-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 the compression cylinder 12 and the expansion
cylinder 14.
The geometric (or volumetric) compression ratio of20

thecompression cylinder

12 of

for

split-cycleinreferred to asengine.

enginesthesplit-cycle engine

general)"compression

The geometricratio"(or volumetric)ishereinofthesplit-cycle engines in general)(andcommonly

split-cycle

compression ratio of

the expansion cylinder 14 of split-cycle engine 102510(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 enclosedthe30

cylinderreciprocating(including
therein

is

all
at

(or trapped)

recesses)

its

when

bottom deadvolume inapistoncenter(BDC)

position to the enclosed volume(i.e.,

clearance volume)thepiston

is

at

its

Specificallyfor

split-cycle(TDC)

cylinderwhen

position.

said

SUBSTITUTE SHEET (RULE 26)

top

dead

in

centerenginesaswo 2011/115873

PCT/US2011/028285

10

definedherein,thecompression

ratio

of

a

compression

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 when5

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

10

30

(e.g.,

20 to

to

1,

40

to

greater)withinthecylinder12,anoutwardly opening(opening

outwardly away

from

the

cylinder)

valve

24

at

the

flow

from

control

20 to 1,orpoppetcrossoverthe22.

compression
Due

30 to 1'40 to 1,25cylindervery

tocompression

compression
inlet

passagecrossovercrossover passage(e.g.,

1,high(XovrC)

is

used

to

12

into

the

expansionor greater)

ratioswithin the

expansion cylinder 14, an outwardly opening poppet crossover
15

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,

20

26 are timed to maintainpressure

inpressure(typically 20 bar or higher atthecrossoverpassage

22

at

a

high

minimum

full

load)

duringall four strokes of the Otto cycle.
At

least

one

fuel

injector

28

injects

fuel

into

the pressurized air at the exit end of the crossover passage
22 in correspondence with the XovrE valve 26 opening,
25

occursdead

shortly before expansion piston
centerposition.

The

air/fuel

30

reachescharge

which

its

top

enterstheexpansion cylinder 14 when expansion piston 30 is close to
its

30

top

dead

centerdescent

fromits

position.

top deadcenterXovrE valve 26 is still open,
a

spark

plug

tip

39

that

As

pistonposition,spark plug 32,

protrudes

into

30

begins

its

and

while

the

which includes

cylinder14,isfired to initiate combustion in the region around the spark
plug

tip

39.

Combustion

can

be

initiated

SUBSTITUTE SHEET (RULE 26)

while

the

wo 2011/115873

PCT/US2011/028285

11

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 past5

preferably,isbetweencenter(TDC)

initiated

10

as

(TDC)

posit ion.

Most

combustion can be initiated while the expansion

pistonsuch

its top dead center

10 and 20 degrees

position.

throughwithAdditionally,

other

glow

CA pastignitionplugs,

top dead

combustion

devicesmicrowave

its

and/ormaybemethods,

ignitiondevicesor

exhaust

gases

are

through compression ignition methods.
Duringtheexhauststroke,pumped out of the expansion cylinder 14 through exhaust port
35 disposed in cylinder head 33.
exhaust valve 34,
15

port 35,

An inwardly opening poppet

disposed in the

inlet

the

exhaustpassage 22.
35 do
20

port

That is,35

areThe exhaust valve 34

separate

from

the

crossoverexhaust valve 34 and the exhaust port

not make contact with,or arenotdisposedin,thecrossover passage 22.
With the split-cycle engine concept,
engineparameters

length,(i.e. ,

volumetriccompression
25

the exhaust

controls fluid communication between the expansion

cylinder 14 and the exhaust port 35.
and

31 of

12

and

the geometricbore,

stroke,connecting

rodcompression

ratio,

etc.)

the

expansion

14cylindersareofgenerally

independent from one another.

For example, the crank throws

36,

cylinder38forcylinder 14,

thecompression

respectively,

12

and

expansion

may have different radii and may

be phased apart from one another such that top dead center
(TDC)
30

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.

SUBSTITUTE SHEET (RULE 26)

wo 2011/115873

PCT/US2011/028285

12

The geometric independence of engine parameters inthe split-cycle engine 10 is also one of the main reasons
why pressure can be maintained in the crossover passage 22
as discussed earlier.
5

reaches

its

topSpecifically, the expansion piston 30

deadcenterposition

prior

to

the

compression piston reaching its top dead center position byadiscreetanglephase angle

degrees).

(typically between

This

phase

angle,

10 andtogether

30 crankwithpropertiming of the XovrC valve 24 and the XovrE valve 26, enables
10

thesplit-cycle

engine10

tomaintainpressurecrossover passage 22 at a high minimum pressure

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
15

and the XovrE valve 26 such that the XovrC and XovrE valves
are both open for a substantial period of time
crankshaft

rotation)

duringwhich

the(or period of

expansion

piston30

descends from its TDC position towards its BDC position andthe20

compression

piston20

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

are

both

transferred

open,
( 1)

a

from

the compression

to

the

period,from

expansion

cylinderits

During the period of

equal

mass

cylinder

of
12

air

is

into

the

from the crossover passage 22
14.

Accordingly,

duringthisthe pressure in the crossover passage is prevented

dropping(typically

30

( 2)

from

that the crossover valves 24,

substantiallycrossover passage 22 and25

simultaneously ascends

20,

below

a

predetermined

minimum

30,

40

bar

duringorabsolutepressure
full

load

operation).

Moreover,engine cycle(typically 80% of the entire engine cycle orgreater),

XovrC

the

during a substantial portion of the

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.

SUBSTITUTE SHEET (RULE 26)

As a result,

wo 2011/115873

PCT/US2011/028285

13

the pressure in the crossover passage 22 is maintained at apredetermined minimum pressureduringallfourstrokesofmethodofhavingthethe engine's pressure/volume cycle.
For5

purposesherein,the

XovrC 24 and XovrE 26 valves open while the expansion piston
30 is descending from TDC and the compression piston 20 isascending 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-Pull
10method ofenablesgas

thetransfer.

pressure

in

It

is

the

crossoverthe

Push-Pullmethod

that

22

the

passageofsplit-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.
15

As

discussed

disposedintheseparatefromarrangement

theexhaust

port

of

the

cylinderpassage

22.

The

exhausttheofearlier,crossoverthe exhaust

35

valve

34

not

the crossover passage 22, and therefore
20

valve

34

is

head

33

structural

being disposed

t~e

in

exhaust port 35

notsharing any common portion with

22,

is preferred in order to maintain the trapped mass ofgas

in the crossover passage 22 during the exhaust stroke.

Accordingly,

large

cyclic drops

in

the

crossover passage

pressureareprevented

which may force the pressure in the crossover passage below
25

the predetermined minimum pressure.
XovrE valve 26 opens shortly before the expansion
piston30

reaches

time,

the

pressureits

top dead

ratio

of

centertheposition.

pressure

in

At

this

crossoverpassage 22 to the pressure in expansion cylinder 14 is high,30

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.

SUBSTITUTE SHEET (RULE 26)

In other words,

wo 2011/115873

PCT/US2011/028285

14when XovrE valve 26 opens,
22

issubstantially higher thancylinder 14
This5

the pressure in crossover passage

highand/orthepressure(typically in the order of 20 to 1 or greater).
pressure

fuel

ratio

chargehigh speeds.

tocausesflow

initialflow

into expansion

10

the

it

advantageouscauses a

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

to

This sonic flow

split-cycle

rapid combustion event,engine10

tothoughignitionmaintainisengine

which

high

10

enables

combustion

initiated

while

the

expansion piston 30 is descending from its top dead center
position.
The split-cycle air-hybrid engine 10 also includes
15

an air reservoir(tank)

40,

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

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,
20

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

25

reservoir(tank)

passageto22

divided into aandasecond

port

44,

which

the air

tank

40.

first
air

extends
The air

air reservoir

reservoir(tank)

fromcrossover

tank

port

44

is

(tank)

port

section46

port

section48.

The

first air tank port section 46 connects the air tank valve
42 to the crossover passage 22, and the second air tank port
section 48 connects the air tank valve 42 to the air tank
30

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
when the tank valve 42 is closed.

SUBSTITUTE SHEET (RULE 26)

wo 2011/115873

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15

The tank valve 42 may be any suitable valve device
For example,

or system.

the tank valve 42 may be an active

valve which is activated by various valve actuation devices(e.g.,
5pneumatic,

Additionally,

hydraulic,cam,

the tank valve

system with twoelectricorthe

42 may comprise aor more valvesactuated withlike).

tank valve
two or moreactuation devices.
Air

tank

40

is

utilized

to

store

energyintheform of compressed air and to later use that compressed air
10

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

state of the art.
15

advantages

For instance,

over

the

the split -cycle engine 10

can potentially provide many advantages

in fuel

gains

at

and

NOx

emissionscurrent

reduction

efficiency

relatively

lowmanufacturing and waste disposal costs in relation to othertechnologies

on

the

market,such

asdieselengines

andelectric-hybrid systems.
20

By
closingofselectively
the

air

tank

controlling

the

valve

thereby42

andopening

and/orcontrolling

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

the

split-cycle air-hybrid engine

Engine Firing
25

(EF)

mode,

10 is operable

an Air Expander

(AE)

mode,

in an
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

30

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

40

without

combustion

cylinder14(i.e.,

utilizingthekineticnofuelenergyoccurringin

expenditure),ofavehicleSUBSTITUTE SHEET (RULE 26)

theexpansion

such

as

by

includingthewo 2011/115873

PCT/US2011/028285

16

engine10duringThe

braking.

FC

mode

is

an

air-hybrid

operating mode in which excess compressed air not needed for5

combustion

is stored inthan fullengine load

at constant speed) .
mode

has

an

the air(e.g.,

tank

40,such asengine idle,

at

less

vehicle 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.
10

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 occurringinThe

the expansion cylinder
AEF

mode

is

an

14

(i.e.,

air-hybrid

no

fuel

operatingexpenditure).
mode

in

which

compressed air stored in the air tank 40 is utilized in the15

expansion cylinder 14 for combustion.
The air tank valve 42 may be a fully controllable
variably actuated valve that can be kept closed,

held open,

or selectively opened and closed at any desired timing.
the
20

EF

mode,

the

air

reservoir

valve

42

is

kept

In

closedduring the entire rotation of the crankshaft 16 to isolate
the air reservoir 40 from the rest of the engine.

In the AE

and AEF modes, the air reservoir valve 42 is kept open for aduration(inCA

degrees)

that

is

at

least

duration of the XovrE valve 26 opening event,
25

use

in

the

expansion

compressed air.
modes,

30cylinder

14

of

as

long

as

a

to allow forpreviously

storedIn a specific embodiment, in the AE and AEF

the air reservoir valve

42 may be

kept open during

the entire rotation of the crankshaft 16.

In the AC and FC

modes,

the air reservoir valve 42 is selectively opened andclosedduringasinglerotationofthecrankshaft

16

toallow for flow of compressed air into the air reservoir 40
in order to store the compressed air for later use.

SUBSTITUTE SHEET (RULE 26)

wo 2011/115873

PCT/US2011/028285

17

In the EF mode, the compression piston 20 draws inand compresses inlet air for use in the expansion cylinder
14.

The compressed air from the compression cylinder 12 isadmitted
5

to

the

expansion

cylinderbeginning of an expansion stroke,

14

with

fuel,

at

which is ignited,theburnedand expanded on the same expansion stroke of the expansion
piston 30,

transmitting power to the crankshaft 16, and the

combustion

products

aredischarged ontheexhauststroke.

Since compressed air is neither stored in nor released from10

the air tank 40

in the EF mode,

the air tank valve

42

isclosed.
In the AE mode,tank

4 0 isadmit ted tocompressed air stored in the air

the expansion

beginning of an expansion stroke.
15

cy 1 inder

at

the

Since in this mode the

air tank valve 42 is kept open at least as long as the XovrE
valve

26,

air

flow

into

the

expansion

controlled by the XovrE valve.
same

expansion

strokeofcylinder14is

The air is expanded on thetheexpansiontransmitting power to the crankshaft 16,
20

14,

pistonand the30,(expanded)

air is discharged on the exhaust stroke.
In the AEF mode,

compressed air stored in the airtank 40 is admitted to the expansion cylinder 14 with fuel,at the beginning of an expansion stroke.

Since in this mode

the air tank valve 42 is kept open at least as long as the
25

XovrE

valve

26,

flow

of

the

air/fuel

mixtureintotheexpansion cylinder 14 is controlled by the XovrE valve 26.
The air/fuel mixture is ignited,same

expansion

strokeofburned and expanded on thetheexpansiontransmitting power to the crankshaft 16,
30

piston30,

and the combustion

products are discharged on the exhaust stroke.
In the AC mode, the compression piston 20 draws inand compresses inlet air.

The compressed air is then stored

SUBSTITUTE SHEET (RULE 26)

wo 2011/115873

PCT/US2011/028285

18
in the air tank 40 by selectively opening and then closing
the air tank valve 42.
In the FC mode,the compression piston 20 draws inand compresses inlet air for use in the expansion cylinder

5

14 during a single rotation of the crankshaft 16.
the

air

compressed

admit ted

to

from

the

expansion

thecompression

cylinderbeginning of an expansion stroke,

14cylinder

with

which

Some offuel,is ignited,

12

is

at

the

burnedand expanded on the same expansion stroke of the expansion
10

piston,transmitting

combustion

products

power
are

to

the

discharged

crankshaft,

on

the

and

exhaustthe

stroke.

The air tank 40 is also charged with compressed air during
the same single rotation of the crankshaft 16 by selectively
opening and then closing the air tank valve 42.

15

In an exemplary embodiment shown in FIGS.
the air tank valve

42

disposed in the air

reservoir port

crossover passage 22.
bend
20(i.e.,

elbow)

2 and 3,is an outwardly opening poppet valve
44

and connected to the

The air tank port 4 4 has an angularallowing the stem 4 3 of the valve 4 2 toextend vertically from the valve head.

The angular bend isshown as a generally right-angle bend,

but may be an S-curve

or

other

similarly

shapedelbow.

A pneumatic,

hydraulic,electric or mechanical valve actuation device 45 or the likemay be disposed at the distal end of the stem 43.
25

air

tank

valve

42

is

exemplified

asan

While theoutwardly

opening

poppet valve, one of ordinary skill in the art would realize
that

the

air

tank

valve

combination thereof,

30

may

poppetvalve,

apintlevalve,

or

like,

check

one

or

more

the following valve types:

opening

activated

be

the
valve

rotary(such

valve,

and

may

as

a

a

combination.

SUBSTITUTE SHEET (RULE 26)ora

an inwardly

sleeveinclude
reed

of,

a

valve)

valve,

apressure
inthewo 2011/115873

PCT/US2011/028285

19

Althoughreferencetothespecific

invention

has

been

embodiments,

itshoulddescribed
bebyunderstoodthat numerous changes may be made within the spirit and scope
of
5

the

inventive

concepts

described.

Accordingly,itisintended that the invent ion not be limited to the describedembodiments,

but that it have the fullscope defined by thelanguage of the following claims.

SUBSTITUTE SHEET (RULE 26)

wo 2011/115873

PCT/US2011/028285

20

CLAIMS

What is claimed is:
1.
5

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

compression

cylindercrankshaft

such

that

pistonslidablyreceived

withinandoperatively

connected

tothecompression

pistonathe

reciprocatesthrough an intake stroke and a compression stroke during a10

single rotation of the crankshaft;anexpansion

expansion

cylindercrankshaft

suchpistonandthat

slidablyreceived

withinanoperatively

connected

to

the

the

expansion

pistonreciprocatesthrough an expansion stroke and an exhaust stroke during a15

single rotation of the crankshaft;a20

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 delivercompressed air to the expansion cylinder; and25

an air reservoir valve selectively controlling air
flow into and out of the air reservoir;
theEngine Firing

engine(EF)

mode,

Compressor (AC) mode,
30

being

operableinan Air Expander

one

or

(AE)

more
mode,

of

an

an Airan Air Expander and Firing (AEF) mode,

and a Firing and Charging (FC) mode, wherein:inthe

EF mode,the air

reservoir valve

closed during the entire rotation of the crankshaft;

SUBSTITUTE SHEET (RULE 26)

is

kept

wo 2011/115873

PCT/US2011/028285

21

in the AE and AEF modes,

the air reservoir valve

is kept open for a duration that is at least as long as aduration of the XovrE valve opening event; andin the AC and FC modes,
5

selectively opened andthe air reservoir valve isclosed during asinglerotation of

the crankshaft.
2.
whereinthe

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

valve

is

an

outwardly

opening

poppet valve.
The split-cycle air-hybrid engine of claim 1,

3.

10
whereintheairreservoir

valve

is

a

fully

controllable

variably actuated valve.
4.

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

wherein the air reservoir valve is
15

kept open for an entire

rotation of the crankshaft.

wherein,5.

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

in

the

AE

and

AEF

modes,

air

flow

into

the

expansion cylinder is controlled by the XovrE valve.
6.
20

wherein,

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

in the EF mode,the compression piston draws in andcompresses inlet air for use in the expansion cylinder,

andcompressed air

with

fuel,

at

the

is

admitted

beginning

of

to

the

expansionanexpansion

cylinderstroke,which

isignited, burned and expanded on the same expansion stroke of25

the expansion piston,
and

the

combustiontransmitting power to the crankshaft,products

are discharged ontheexhauststroke.

30

7.

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

wherein,inthereservoirisadmitted

AE

mode,
to

compressedtheexpansion

air

from

cylinder,

the

air

at

the

beginning of an expansion stroke, the air is expanded on thesame expansion stroke of the expansion piston,

SUBSTITUTE SHEET (RULE 26)

transmitting

wo 2011/115873

PCT/US2011/028285

22
power to the crankshaft,and the air

is discharged on theexhaust stroke.
8.
wherein,5

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

in

the

AEF

mode,

compressed

air

the

reservoir is admit ted to the expansion cylinder withat the beginning of an expansion st!='oke,burnedandexpanded

expansion piston,
the
10

from

combustion

on

the

fuel,

which is ignited,ofthetransmitting power to the crankshaft,andproducts

same

air

are

expansiondischarged

strokeontheexhauststroke.
9.
wherein,

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

in the AC mode, the compression piston draws in andcompresses inlet air, which is stored in the air reservoir.
10.
15

wherein,in the FC mode, the compression piston draws in andcompresses
during a

20

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

inlet

air

for

use

in

the

expansion

single rotation of the crankshaft,cylinderand compressed

air is admitted to the expansion cylinder with fuel,at thebeginning of an expansion stroke,burnedwhich is ignited,and expanded on the same expansion stroke of the expansion
piston,transmitting

combustion

products

power
are

to

the

discharged

crankshaft,

on

the

exhaustandthestroke,and the air reservoir is charged with compressed air during
the same single rotation of the crankshaft.
25

11.

A

methodofoperatingasplit-cycle

air-hybrid engine including:a crankshaft rotatable about a crankshaft axis;acompression
30

crankshaft

compression
cylinder
such

that

pistonslidablyreceived

withinandoperatively

connected

tothecompression

through an intake stroke and apistonathe

reciprocatescompression stroke during asingle rotation of the crankshaft;

SUBSTITUTE SHEET (RULE 26)

wo 2011/115873

PCT/US2011/028285

23
anexpansion

expansion

cylindercrankshaft

suchpistonandthat

slidablyreceived

withinanoperatively

connected

to

the

the

expansion

pistonreciprocatesthrough an expansion stroke and an exhaust stroke during a5single rotation of the crankshaft;a10interconnecting

passagecrossovercompression and expansion cylinders,theincludinga(XovrC)

crossover

expansion

crossovercompression(XovrE)crossover passage
valve

and

a

pressuredefining

valve

the

a

chamber therebetween;ancrossoverairreservoir

passageandoperatively

selectively

connected

operable

to

to

the
store

compressed air from the compression cylinder and to delivercompressed air to the expansion cylinder; and15

an air reservoir valve selectively controlling air
flow into and out of the air reservoir;
theengineEngine Firing

(EF)

being

mode,

Compressor (AC) mode,
20

operableinone

an Air Expanderor more

(AE)

mode,

of

an

an Airan Air Expander and Firing (AEF) mode,

and a Firing and Charging(FC) mode;the method including the steps of:in theclosedduring

EF mode,thekeeping

entiretherotation

airofreservoir

the

valve

crankshaft

toisolate the air reservoir;
25in the AE and AEF modes,
valve

open

for

a

durationthatkeeping the air reservoir
is

at

least

as

long

as

a

duration of the XovrE valve opening event; and
in

the

AC

and

FC modes,selectively opening

andclosing the air reservoir valve during a single rotation of30

the crankshaft to allow for flow of compressed air into the
air reservoir for storage of compressed air.
12.

The method of claim 11,

further including thestep of:

SUBSTITUTE SHEET (RULE 26)

wo 2011/115873

PCT/US2011/028285

24
in the AE and AEF modes,

keeping the air reservoir

valve open for an entire rotation of the crankshaft.
13.

The method of claim 11,

further including thesteps of:selecting one of the AE mode and the AEF mode; and5controlling air

flow

into

the

expansion cylinder

by opening and closing the XovrE valve.
14.

The method of claim 11,

further including thesteps of:selecting the EF mode;

10

drawinginandcompressing

inlet

air

with

the

compression piston; and15

admittingcompressedcylinderintoexpansion

beginningofburned

and

the
an

expansion

expanded

expansion piston,

on

air

cylinderstroke,

the

from

same

the

the

compression

with

fuel,

fuel

being

expansion

attheignited,strokeofthetransmitting power to the crankshaft,anddischarging the combustion products on the exhaust stroke.
15.
20

The method of claim 11,

further including thesteps of:selecting the AE mode; andadmitting
into

25

the

expansion

expansion

stroke,stroketheofcompressed

air

from

cylinder,

at

the

air

on

expandingtheexpansion piston,

the

air

reservoir

beginningthetransmittingofansame expansion
power

to

the

crankshaft, and discharging the air on the exhaust stroke.
16.

The method of claim 11,

further including thesteps of:selecting the AEF mode; and30

admittingcompressed

air

from

the

air

reservoir

into the expansion cylinder with fuel,at the beginning ofan expansion stroke,burned and expanded

on

the

same

which is ignited,

expansion

strokeoftheexpansion

SUBSTITUTE SHEET (RUL~ 26)

piston,wo 2011/115873

PCT/US2011/028285

25transmitting

power

to

the

crankshaft,anddischarging

thecombustion products on the exhaust stroke.
17.

The method of claim 11,

further including thesteps of:selecting the AC mode;

5

drawinginandcompressing

inlet

air

with

the

compression piston; andstoring the compressed air in the air reservoir.
18.
10

The method of claim 11,

further including thesteps of:selecting the FC mode;
drawingcompressioninpistonandcompressing

duringa

inletsingle

air

with

the

rotationofthecrankshaft;15

admittingcylinder with fuel,
the

fuel

being

compressed

air

into

burnedandexpanded

expansion stroke of the expansion piston,

20

expansionat the beginning of an expansion stroke,

ignited,to the crankshaft,

the

on

the

same

transmitting powerand discharging the combustion productson the exhaust stroke; andchargingtheairreservoir

withcompressed

during the said single rotation of the crankshaft.

SUBSTITUTE SHEET (RULE 26)

airwo 2011/115873

PCT/US2011/028285

1/2

FIG. 1

wo 2011/115873

PCT/US2011/028285

2/2

45

FIG. 2
43

44

FIG. 344

INTERNATIONAL SEARCH REPORTInternational application No.
PCT/US2011/028285

A.

CLASSIFICATION OF SUBJECT MATTER

IPC(8) - F02B 33/22 (2011.01)
USPC- 123/?0R
According to International Patent Classification (IPC) or to both national classification and IPC
B.

FIELDS SEARCHED

Minimum documentation searched (classification system followed by classification symbols)
IPC(8). F02B 3/00, 11100, 19/06, 33/00, 33/02, 33/06, 33/22, 41/02, 41104, 41/06 (2011.01)
USPC • 60/620, 712; 123/26, 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)
PatBaseC.

DOCUMENTS CONSIDERED TO BE RELEVANT

Category*X-

Citation of document, with indication, where appropriate, of the relevant passages
US 2007/0157894 A1 (SCUDERI et al) 12 July 2007 (12.07.2007) entire documentyyRelevant to claim No.
1,3-18------2

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

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

DSpecial categories of cited documents:"T'"A" document defining the general state of the art which is not considered
to be of particular relevance"E" earlier application or patent but published on or after the international "X"
filing date"L" document which may throw doubts on priority claim(s) or which iscited to establish the publication date of another citation or other "Y"
special reason (as specified)"0" document referring to an oral disclosure, use, exhibition or othermeans"P" document published prior to the international filing date but later than "&"the priority date claimed
Date of the actual completion of the international search
05 May 2011
Name and mailing address of the ISA!US
Mail Stop PCT, Attn: ISA/US, Commissioner for Patents
P.O. Box 1450, Alexandria, Virginia 22313-1450
Facsimile No. 571-273-3201
Form PCTnSA/210 (second sheet) (July 2009)2

later document published after the international filing date orcferiority
date and not in conflict with the ap~lication but cited to un erstandthe principle or theory underlying e invention
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
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

20 MAY Inn
Authorized officer:
Blaine R. Copenheaver
PCT Helpdesk: 571-272-4300
PCT OSP: 571-272-7774