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

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

22 September 2011 (22.09.2011)

PCT(51) International Patent Classification:
F02B 33122 (2006.01)(21) International Application Number:
PCT/US20ll/028278(22) International Filing Date:
14 March 2011 (14.03.2011)

WO 2011/115869 A1
West Sussex BN43 6WL (GB). GILBERT, Ian; 67
Beach Green, Shoreham-by-Sea, West Sussex BN43 5YE(GB).
(74) Agents: FILDES, Christopher, J. et al.; Fildes & Outland, P.C., 20916 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,
English(26) Publication Language:
CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO,(30) Priority Data:
DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT,
15 March 2010 (15.03.2010)
61/313,831
us
HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP,
61/363,825
13 July2010 (13.07.2010)
us
KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD,
18 July2010 (18.07.2010)61/365,343
us
ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI,NO,
NZ, OM, PE, PG, PH, PL, PT, RO, RS, RU, SC, SD,(71) Applicant (for all designated States except US): SCUDSE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR,
ERI GROUP, LLC [US/US]; 1111 Elm Street, Suite 33,
TT, TZ, VA, UG, US, UZ, VC, VN, ZA, ZM, ZW.
West Springfield, MA 01089 (US).
(25) Filing Language:

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

Shoreham-by-Sea, West Sussex BN43 6RB (GB).
BADAIN, Nicholas; 37 Rosslyn Road, Shoreham-by-Sea,(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,-::: ------------------------------------------------------------------------------------------- FIG. 1;;;;;;;;;;;;;;;[Continued on next page](54) Title: SPLIT-CYCLE AIR-HYBRID ENGINE WITH FIRING AND CHARGING MODE

(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 andcrossover expansion (XovrE) valve therein. 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 a Firing and Charging (FC) mode ofthe engine, the air reservoir valve is kept closed until the XovrE valve is substantially closed during a single rotation of the crankshaft such that the expansion cylinder is charged with compressed air before the air reservoir is charged
with compressed air.

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

12

W 0 2011/11586 9 A 1 11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ, Published:
TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, with international search report (Art. 21 (3))
EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU,
LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK,
SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ,
GW, ML, MR, NE, SN, TD, TG).

wo 2011/115869

PCT/US2011/028278

1

SPLIT-CYCLE AIR-HYBRID ENGINE WITH FIRING AND CHARGING MODETECHNICAL FIELD

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

to such an engine incorporating an air-hybrid system.

BACKGROUND OF THE INVENTION

For
10engine"aspurposes

used

in

of

the

clarity,present

theterm"conventional

applicationreferstoaninternal combustion engine wherein all four strokes of thewell- known

Otto

cycle

compression,

expansion(i.e.,

the(or power)

intake(orinlet) ,and exhaust strokes)

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

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

for

purposesofclarity,thefollowing

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

split-cycle

engineasreferredtohereincomprises:25

a crankshaft rotatable about a crankshaft axis;acompression
crankshaft

compression
cylinder
such

that

pistonslidablyreceived

withinandoperatively

connected

tothecompression

pistonathe

reciprocatesthrough an intake stroke and a compression stroke during a30

single rotation of the crankshaft;wo 2011/115869

PCT/US2011/028278

2anwithinexpansionan expansion(power)cylinderpistonslidablyreceived

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

compression and expansion cylinders,
including

at

least

a

crossoverinterconnecting

thethe crossover passage

expansion(XovrE)

valve

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

2003 to Scuderi and United States

granted October 11,
15

Patent No.

Patent No.

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

and6, 952,923

both of whichcontain an extensive

similar-type

engines.

In

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

Split-cycle
cycle

enginewithanair-hybrid
airengines

reservoir

combineand variousasplit-

controls.

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

energyreservoir.
25

in

the

form

of

compressed

air

in

the

air

The compressed air in the air reservoir is later

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

air-hybrid

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

compression
crankshaft

compression
cylinder
such

that

pistonslidablyandoperatively

thecompression

received withinconnected

pistontoathe

reciprocatesthrough an intake stroke and a compression stroke during asingle rotation of the crankshaft;wo 2011/115869

PCT/US2011/028278

3

anwithinexpansionan expansion(power)cylinderpistonslidablyreceived

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

compression and expansion cylinders,
including

at

least

a

crossoverinterconnecting

thethe crossover passage

expansion(XovrE)

valve

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

passageandoperatively

selectively

connected

operable

to

to

the
store

compressed air from the compression cylinder and to deliver
15

compressed air to the expansion cylinder.
United States
8,

20

Patent No.

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

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

air-hybrid

andsimilar-type

patent discloses details

engines.

In

addition,of prior hybrid systems

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

Enginemodes.

Firing(EF)

In the EF mode,

mode)

reservoir.

connecting

mode
and

(also commonly called
four

basic

air-hybrid

operating without the use of its

In the EF mode,

the

in a

the engine functions as a non-air

hybrid split-cycle engine,
air

(NF)

run

crossoverpassageatank valve operatively
to

the

air

reservoir

remains closed to isolate the air reservoir from the basic
30

split-cycle engine.
The

split-cycle

air-hybrid

engineoperates

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

The fourwo 2011/115869

PCT/US2011/028278

4

Air

1)

Expandercompressed

(AE)

air

mode,

energy

which

from

the

includes
air

using

reservoir

without combustion;
2)
5

Air Compressor(AC)compressedenergyairmode,which includes

into

the

air

storing

reservoir

without combustion;
3)

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

4)Firingandstoring

Charging

compressed

(FC)
air

mode,

which

includesenergy

into

the

air

AE,

AC,

reservoir with combustion.
However,further

AEF and FC,
15

optimization of these modes,EF,

is desirable to enhance efficiency and reduce

emissions.

SUMMARY OF THE INVENTION

The present invention provides a split-cycle air20

hybrid engine in which the use of the Firing and Charging(FC)mode isoptimized for potentially any vehicle in any

drive cycle for improved efficiency.
Moreparticularly,

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

invention includes a crankshaft rotatable about a crankshaft
axis.

A compression piston iscompression
crankshaft

cylinder
such

that

slidably received within aandoperatively

thecompression

connected
pistontothereciprocatesthrough an intake stroke and a compression stroke during a30

singlerotationvalve

selectively

cylinder.
an

of

the

crankshaft.

controls

air

flow

An

intake

into

the

(or

inlet)

compression

An expansion piston is slidably received within

expansion

cylinderandoperatively

connected

tothewo 2011/115869

PCT/US2011/028278

5

crankshaft

such

that

the

expansion

pistonreciprocatesthrough an expansion stroke and an exhaust stroke during asinglerotationofthecrankshaft.

A crossover

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

and

pressure10

achamber

expansion(XovrE)

therebetween.

operatively

connected

selectively

operablecompression

cylinder.

to
to

An

valve
air

definingareservoirispassageandthecrossoverstore

compressedairreservoir valve

An(XovrC)

air

from

the

selectively

controls air flow into and out of the air reservoir.

The

engine is operable in a Firing and Charging

In

the FC mode,the15

crossover

The

XovrE

(FC)

mode.

the air reservoir valve is kept closed until

valve

is

substantiallyclosedduringasinglerotation of the crankshaft such that the expansion cylinder
is charged with compressed air before the air reservoir ischarged with compressed air.
A methodofoperatingengine is also disclosed.
20asplit-cycle

air-hybrid

The split-cycle air-hybrid engine

includes a crankshaft rotatable about a crankshaft axis.

A

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

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

thecrankshaft.

Anintake valve

selectively controls

flow into the compression cylinder.
slidablyreceived

operatively
expansion
30

and

an

connected

pistonexhaustcrankshaft.

withintostrokeA

An expansion piston isanexpansionthecrankshaft

reciprocates
duringcrossoverthroughaaircylinder
such

that

and
the

an

expansion

strokesinglerotationoftheinterconnects

thepassagecompression and expansion cylinders.

The crossover passage

includes(XovrC)acrossovercompression

valve

and

a

wo 2011/115869

PCT/US2011/028278

6crossover

expansion(XovrE)

chamber

therebetween.

An

valve
air

defining

reservoiraispressure

operatively

connected to the crossover passage and selectively operable
to store compressed air from the compression cylinder.
5

air reservoir valve
out

of

the

air

FiringandCharging

with

the

drawing10

selectively controls air flow

reservoir.

present

(FC)

The
mode.

inventionin and compressing

compression

piston;engineTheisincludes

the

inlet

intake)admitting(orinto and

operablemethodininaaccordance

following

compressedAnsteps:

air with
air

from

the
the

compression cylinder into the expansion cylinder with fuel,atthebeginningofanexpansion

stroke,

the

fuel

being

ignited, burned and expanded on the same expansion stroke ofthe expansion piston,
15

transmitting power to the crankshaft,and the combustion products being discharged on the exhauststroke; and keeping the air reservoir valve closed until the
XovrE valve is substantially closed during a single rotationofthecharged20

crankshaft
with

such

that

compressed

expansion

cylinderisbeforetheairreservoirisfeaturesandadvantages

air

the

charged with compressed air.
These
invention will

and
be

other

more

fully

understood

from

the

of

the

followingdetailed description of the invention taken together with theaccompanying drawings.
25

BRIEF DESCRIPTION OF THE DRAWINGSIn the drawings:
FIG.
30

1 is a lateral sectional view of an exemplary

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

valve

2

is

closingagraphical
timingwithillustration
respect

toofintaketankair

wo 2011/115869

PCT/US2011/028278

7

pressure and tank air
revolutions

perflowrate

atan engine

(rpm)

and

engineminutespeed of 2000

load

of

2

bar

Indicated Mean Effective Pressure (IMEP);
FIG. 3 is a graphical illustration of intake valve
5

durationwithrespect

to

tank

air

pressure

and

tank

air

flowrate at an engine speed of 2000 rpm and engine load of 2
bar IMEP;
FIG.
compression
10

4

is

(XovrC)agraphical

illustrationofcrossovervalve duration with respect to tank airpressure and tank air flowrate at an engine speed of 2000 rpm
and engine load of 2 bar IMEP;
FIG.
expansion

5(XovrE)isagraphical

illustrationofcrossovervalve

duration

with

to

tank

respectairpressure and tank air flowrate at an engine speed of 2000 rpm
15

and engine load of 2 bar IMEP;
FIG.

6 is a graphical illustration of XovrC valve

opening timing with respect to tank air pressure and tank air
flowrate at an engine speed of 2000 rpm and engine load of 2
bar IMEP;
20

FIG.

7 is a graphical illustration of XovrC valve

closing timing with respect to tank air pressure and tank air
flowrate at an engine speed of 2000 rpm and engine load of 2
bar IMEP;
FIG.
25

8 is a graphical illustration of XovrE valve

opening timing with respect to tank air pressure and tank air
flowrate at an engine speed of 2000 rpm and engine load of 2
bar IMEP;
FIG.

9 is a graphical illustration of XovrE valve

closing timing with respect to tank air pressure and tank air
30

flowrate at an engine speed of 2000 rpm and engine load of 2
bar IMEP;
FIG.

10

is

a

graphical

illustration

valve opening timing with respect to

of

air

tank

tank air pressure andwo 2011/115869

PCT/US2011/028278

8tank air flowrate at an engine speed of 2000 rpm and engine
load of 2 bar IMEP;
FIG.

11

is

a

graphical

illustration

of

air

tank

valve closing timing with respect to tank air pressure and5tank air flowra te at an engine speed of 2 0 0 0 rpm and engine
load of 2 bar IMEP; and
FIG.

12

is

a

graphical

illustration

of

fuel

flowrate with respect to tank air pressure for various tank
air flowrates at an engine speed of 2000 rpm and engine load
10of 2 bar IMEP.

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

all valve opening andare measured in crank angle degrees

after

top dead center of the expansion piston (ATDCe) .
Unless20

otherwise

are in crank angle degrees
Air tank

specified,

all

valve

durations(CA) .

(or air storage tank): Storage tank for compressed

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

30

Bar: Unit of pressure, 1 barmean

10 5 N/m 2

=

BMEP:

Brake

effective

pressure.

referstotheoutputas

outputshaft),

after

frictionfor.

Brake Mean Effective PressuredeliveredtolossesThethe"Brake"crankshaft(FMEP)(BMEP)

term

are

(or

accounted

is the engine's

brake torque output expressed in terms of a mean effective
pressure(MEP)

value.

BMEP

is equal

divided by engine

displacement.

parameter

after

taken

the

This
lossestothe brake

torqueistheperformance

due

to

friction.

wo 2011/115869

PCT/US2011/028278

9
Accordingly,

BMEP=IMEP-friction.

Friction,in this case isusually

expressed

of

value

known

its

associatedits

associated

also

in

terms

Frictional Mean Effective Pressure
Compressor:
5The

compression

an MEP

as(or FMEP)

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

expansion

cylinderandexpansion piston of a split-cycle engine.
FMEP: Frictional Mean Effective Pressure.
g/s: Grams per second.
10

IMEP:

Indicated

Mean

Effective

Pressure.

The

term

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

Inlet

Also commonly referred to(or intake) :Inlet valve.

as an intake valve.
15

Inlet

air

(or

intakecylinder on an intake
Inlet valve

air):

Air drawn(or inlet)

into

the

compression

stroke.

(or intake valve):

Valve controlling intake ofgas into the compression cylinder.
RPM: Revolutions Per Minute.
20

Tank

valve:

Valve

connecting

the

Xovr

passagewith

thecompressed air storage tank.
Valve duration:

The interval in crank degrees between startof valve opening and end of valve closing.
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)

the Xovr passage.

valves:Valvesatthecompressor end of

wo 2011/115869

PCT/US2011/028278

10

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.
S

The split-

cycle air-hybrid engine 10 replaces two adjacent cylindersofaconventional

enginewithacombination

of

one

compression cylinder 12 and one expansion cylinder 14.

Acylinder head 33 is typically disposed over an open end of
the expansion and compression cylinders 12,
10

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,
15

perform the intake(or inlet)

and compression strokes,

and the expansion cylinder 14, together with its associatedexpansion piston 30,
exhaust strokes.

perform the expansion(or power)

and

The Otto cycle is therefore completed inthese two cylinders 12, 14 once per crankshaft 16 revolution(360 degrees CA) about crankshaft axis 17.
20

25

During the intake stroke, intake (or inlet) air is
drawn

into

port

19

the

compression

disposedinthecylindercylinder12through

head

33.

an

An

intakeinwardly

opening(opening inwardly into the cylinder and toward thepiston)poppetintake(orinlet)

valve

18

controls

fluidcommunication between the intake port 19 and the compression
cylinder 12.
During30

piston20

chargeinto

thepressurizes
thecompression
the

air

stroke,chargecrossover passage

and

the

drives(or port)

typically disposed in the cylinder head 33.

compression

22,

the

air

which

is

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

gas

to

the

crossoverpassage22,

which acts as the intake passage for the expansion cylinder

wo 2011/115869

PCT/US2011/028278

11

14.

In some embodiments,

two or more crossover passages 22

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

thecompression cylinder 12of split-cycle engine

10

for

split-cycle

general)commonlyreferred toengine.

asengines
the

in

is

"compression ratio"

The geometric(or volumetric)

hereinof thesplit-cycle

compression ratio of

the expansion cylinder 14 of split-cycle engine 10
10

split-cycle engines in general)(and(and foris herein commonly referred

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

The

geometric compression ratio of a cylinder is well known in
the art as the ratio of the enclosed (or trapped) volume inthe15

cylinderreciprocating

therein

is

all
at

recesses)

its

when

bottom deadapistoncenter(BDC)

position to the enclosed volume(i.e.,

clearance volume)thesaid piston

is

at

its

Specificallyfor

split-cycle

cylinder

(TDC)

when

position.

defined20(including

herein,thecompression

ratio

top

of

dead

centerenginesainascompression

cylinder is determined when the XovrC valve is closed.

Also

specifically for split-cycle engines as defined herein,

theexpansion ratio of an expansion cylinder is determined when
the XovrE valve is closed.
Due to very high compression ratios
25

1,

1,

40

to

greater)withinthecylinder12,anoutwardly opening(opening

outwardly away

from

the

cylinder)

valve

24

at

the

flow

from

control
30

crossover passage(e.g.,

20 to 1,

or

20 to

to

30

1,

(e.g.,

poppetcrossoverthe
22.

crossoverpassagecompression
Due

30 to 1,40

tocompression

compression
inlet(XovrC)

25

is

used

to

cylinder

12

into

the

very high expansion

to 1,

or greater)

ratioswithin the

expansion cylinder 14, an outwardly opening poppet crossover
expansion (XovrE) valve 26 at the outlet 27 of the crossoverwo 2011/115869

PCT/US2011/028278

12

passage 22 controls flow from the crossover passage 22 into
the expansion cylinder 14.

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

5

thecrossover

26 are timed to maintainpressureinpassage

22

at

a

high

minimumpressure(typically 20 bar or higher at full

load)

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

fuel

into

the pressurized air at the exit end of the crossover passage
22 in correspondence with the XovrE valve 26 opening, which
10

occursshortly before expansion piston 30

deadcenterposition.

The

air/fuel

reacheschargeits

topenterstheexpansion cylinder 14 when expansion piston 30 is close to
its

15

top

dead

centerposition.

descent

fromits

dead center position,

top

XovrE valve 26 is still open,aspark plug

tip

39

that

As

piston30

beginsits

and whilethespark plug 32, which includes

protrudes

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

tip

39.

Combustion

can

be

initiated

while

the

expansion piston is between 1 and 30 degrees CA past its top
20

dead center (TDC) position.

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

center(TDC)

initiatedsuchasposition.

Most

combustion can be initiated while the expansion

piston is between 10
25

(TDC)

position.

throughwithand 2 0 degrees

Additionally,

other

glow

CA past its

ignitionplugs,

combustion

devicesmicrowave

and/or

top deadmaybemethods,

ignitiondevicesor

exhaust

gases

are

through compression ignition methods.
During30

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

An inwardly opening poppet

disposed in the inlet 31 of the exhaust

controls fluid communication between the expansion

wo 2011/115869

PCT/US2011/028278

13cylinder 14 and the exhaust port 35.
and

the

exhaustpassage 22.

port

35

are

separate

from

the

crossoverThat is, exhaust valve 34 and the exhaust port

35 do not make contact with,
5

The exhaust valve 34

or are not disposed in,thecrossover passage 22.
With the split-cycle engine concept, the geometricengineparameters

length,volumetriccompression
10(i.e.,

12

and

bore,

stroke,connecting

rodcompression

ratio,

etc.)

the

expansion

14cylindersofaregenerally

independent from one another.

For example, the crank throws

36,

cylinder38forcylinder 14,

thecompression

12

and

expansionrespectively, may have different radii and may

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

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

engine10

toThis independence enables the split-

potentiallyachievehigherefficiency

levels and greater torques than typical four-stroke engines.
The geometric independence of engine parameters inthe split-cycle engine 10 is also one of the main reasons
20

why pressure can be maintained in the crossover passage 22
as discussed earlier.
reaches

its

topSpecifically, the expansion piston 30

deadcenterposition

prior

to

the

compression piston reaching its top dead center position by25

a discreet phase angle(typically between 10 and 30

crank

angle

phase

properdegrees).

This

angle,

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

engine10

tomaintainpressurecrossover passage 22 at a high minimum pressure

in

the

(typically

20 bar absolute or higher during full load operation) during
30

all four strokes of its pressure/volume cycle.

That is, thesplit-cycle engine 10 is operable to time the XovrC valve 24
and the XovrE valve 26 such that the XovrC and XovrE valves
are both open for a substantial period of time (or period of

wo 2011/115869

PCT/US2011/028278

14

crankshaft

rotation)

during whichtheexpansion piston

30

descends from its TDC position towards its BDC position andthecompression piston

2 0 simultaneously ascends

BDC position towards its TDC position.
5

time
26

(or crankshaft rotation)

are

both

transferred

open,
( 1)

a

to
10

the

period,from

expansion

equal

mass

of

(2)

cylinder

air

is

into

the

from the crossover passage 22
14.

Accordingly,

duringthisthe pressure in the crossover passage is prevented

dropping(typically15

During the period ofcompression cylinder 12crossover passage 22 anditsthat the crossover valves 24,

substantiallyfrom the

from

20,

below

a

predetermined

minimum

30,

40

bar

duringorabsolutepressure
full

load

operation).

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

24

and XovrE valve

26

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

As a result,the pressure in the crossover passage 22 is maintained at apredetermined minimum pressure
20

duringallfourstrokesofmethodofhavingthethe engine's pressure/volume cycle.
For

purposesherein,the

XovrC 24 and XovrE 26 valves open while the expansion piston
30 is descending from TDC and the compression piston 20 isascending toward TDC in order to simultaneously transfer a
25

substantially

equal

mass

of

gas

into

and

out

of

the

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

pressure

in

It

is

the

Push-Pull method thatthecrossoverpassage

22

of

the

split-cycle engine 10 to be maintained at typically 20 bar
30

or higher during all four strokes of the engine's cycle whenthe engine is operating at full load.

disposedAs

discussedintheexhaustearlier,theexhaust

port

of

the

35

valve

cylinder

34

is

head

33

wo 2011/115869

PCT/US2011/028278

15

separate

from

the

crossoverpassagearrangement of the exhaust valve 34
the crossover passage 22,

5

22.

The

structural

not being disposed inand therefore the exhaust port 35

notsharing any common portion with thecrossover passage

22,

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

large

cyclic drops

in pressure

are prevented

which may force the pressure in the crossover passage below
the predetermined minimum pressure.
10

XovrE valve 26 opens shortly before the expansion
piston30

reaches

its

time,

the

pressure

top dead center position.

ratio

of

the

pressure

At

in

this

crossoverpassage 22 to the pressure in expansion cylinder 14 is high,due to the fact that the minimum pressure in the crossover
15

passageistypically20

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

In other words,

when XovrE valve 26 opens, the pressure in crossover passage
22
20

is

substantially higher than the pressure

cylinder 14
This

high

and/or(typically in the order of 20 to 1 or greater).
pressurefuelhigh speeds.

ratio

chargetocausesflow

initial

into

flow

expansionistheadvantageous

it causes

split-cycle

pressures

the
14

air
at

These high flow speeds can reach the speed ofparticularly

becauseofcylindersound, which is referred to as sonic flow.
25in expansion

even

a

to

This sonic flow

split-cycle

rapid combustion event,engine10

tothoughignitionmaintainisengine10

which enables

highinitiatedcombustion
while

the

expansion piston 30 is descending from its top dead center30

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

40,

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

wo 2011/115869

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16

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,

or alternatively eachcrossover passage 22 may operatively connect to separate air
5reservoirs 4 0.
The tank valve 42 is typically disposed in an air
reservoir(tank)

passage 22

to

and

a

second44,whichextends

the air tank 40.

divided into a
10

port

first
air

crossover

The air tank port

air reservoir

reservoir

from(tank)(tank)

port

44

is

port section 46
section

4 8.

The

first air tank port section 46 connects the air tank valve
42 to the crossover passage 22, and the second air tank port
section 4 8 connects the air tank valve 42 to the air tank
40.
15

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.
The tank valve 42 may be any suitable valve device
or system.
20

For example, the tank valve 42 may be an active

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

pneumatic,

Additionally,

hydraulic,the tank valve

system with two

cam,electricorthelike).

42 may comprise a tank valve

or more valvesactuated with two

or moreactuation devices.
25

Air

tank

40

is

utilized to

store

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

power

the

crankshaft

16,

as

described

intheaforementioned United States Patent No. 7,353,786 to Scuderi30

et al.

This mechanical means for storing potential energy

providesnumerousstate of the art.

potential

advantages

For instance,

over

the

current

the split-cycle engine 10

can potentially provide many advantages in fuel efficiency
gains

and

NOx

emissions

reductionatrelativelylowwo 2011/115869

PCT/US2011/028278

17
manufacturing and waste disposal costs in relation to othertechnologies

on

the

market,such

asdieselengines

andelectric-hybrid systems.
By
5

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
Compressor
10

(EF)

mode,

10

is

an Air Expander

operable

(AE)

mode,

in an
an Air(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
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
15

tank

40

without

combustion

cylinder14(i.e.,

noutilizingthekinetic

occurring

fuel

in

the

expenditure) ,energyofavehicleexpansion

such

as

by

includingtheengine 10 during braking.
The
20

which

the

mode

compression

cylindermorestroke

the

of

FC

air

is

an

air-hybrid

pistonthan

expansion

is

draws

neededtooperating

into

the

power

cylinder during

mode

in

compression

theexpansion

combustion(i.e.,

the compressor draws in more air than is required to power
the expander) .
25

The excess

compressed air,combustion,is stored in the air tank 40,

than

full

engineidle,

vehicle cruising at constant speed).

load

operatingnotneeded for

typically at lessconditions(e.g.,

engineThe storage ofcompressed air in the FC mode has an energy cost(penalty)

in that additional negative work is required to be performed30

by the compressor.

Therefore,

it is desirable to have a net

gain when the compressed air is used at a later timetoutilizethecompressed air

in

the

expanderto(i.e.,
producewo 2011/115869

PCT/US2011/028278

18

more positive work than negative work required to store theexcess air during the FC mode) .
The
modes.
5

AE

and

AEF

modes

are

storedenergyusage

The AE mode is an air-hybrid operating mode in which

compressed air stored in the air tank 40 is used to drive
the expansion piston 30 without combustion occurring in the
expansion cylinder 14(i.e.,

no fuel expenditure).

The AEFmode is an air-hybrid operating mode in which compressed air
stored
10

in

the

air

tank

40

is

utilized

intheexpansion

cylinder 14 for combustion.
In the FC mode, the compression piston 20 operates
in

its

compression

mode,

in

that

the

compression

pistondraws in and compresses inlet air for use in the expansion
cylinder 14.
15

mode,

The expansion piston 30 operates in its powerin that compressed air is admitted to the expansion

cylinderstroke,

14

with

fuel,

which isat

ignited,thebeginningofanexpansion

burned and expanded on thesameexpansion stroke of the expansion piston, transmitting power
to
20

the

crankshaft

discharged

on

the

16,

and

exhaustthe

combustion

stroke.

The

FC

products

are

mode

made

is

possible because compression and expansion are split between
the compression cylinder 12

and the expansion cylinder 14.

The expansion cylinder 14 can be run at a load higher thanthe vehicle load.
25

The excess load is then absorbed by thecompression cylinder 12 which compresses more air than the
expansion cylinder
excess(or extra)

14

requiresto powerthevehicle.

Thecharge air is diverted to charging the airtank 40.
Significantly, while the engine 10 is operating in30

the FC mode,

the air tank valve 42 is kept closed until the

XovrE valve

2 6 issubstantially closed during each single

rotation of the crankshaft 16.

Accordingly,

the expansion

cylinder 14 is charged with compressed air before the air

wo 2011/115869

PCT/US2011/028278

19

tank

40

is

charged withcompressed

air.

Thus,

duringasingle rotation of the crankshaft 16, the expansion cylinder
14 and air tank 40 are charged serially (i.e., one after theother,
5ratherthanparallelcharging

provided

by

the

at

the

same

time,

sequence)The

compression

cylinder

which

would

be

air

chargecompressed
12

duringaasinglerotation of the crankshaft 16 is thereby split between the
expansion cylinder 14 and the air tank 40.
Preferably, the air tank valve 42 at least remains
10

closed from within plus or minus 5 degrees CA of when the
XovrC valve

24

opens

substantially open)
when

15

the

XovrE

(i.e.,

from when

the XovrC valve

isto within plus or minus 5 degrees CA ofvalve

2 6 closes(i.e.,

to

when

the

XovrE

valve is substantially closed)

Thus, the air tank valve 42

is

time

substantially closed from adegrees)the(or a position

in CA

at which the compressed air charge begins to entercrossover passage

22

through the XovrC valve

24

to

a

time at which the compressed air charge ceases to enter the
expansion
20cylinderpreventing the

air

14

throughtank

40

expansion cylinder.
valve

24

may

be

XovrE

valve

26,

from being charged before

In an exemplary embodiment,

openedattherebyacrankshaft

thethe XovrC

position(valvetiming) between approximately -23 and -10 CA degrees ATDCe,
and
25

the

XovrE

valve

2 6 may beclosed

at

a

valve

between approximately 11 and 23 CA degrees ATDCe,timingas shown

in FIGS. 6 and 9, respectively.
At all operating conditions of the engine 10,

theair tank valve 42 is opened only after the XovrE valve 26
has30

closed.

For

example,

the

air

tank

valve

42

may beopened at a position that is approximately 5 CA degrees orgreater after the XovrE valve has closed.

Preferably,the

air tank valve 42 may be opened at a position that is in the
range

of

5

2 0 CA degrees

after

the XovrE valve

26 haswo 2011/115869

PCT/US2011/028278

20
closed.

More

preferably,

the

air

tank

valve

42

may

be

opened at a timing that is less than 10 degrees CA after the
XovrE valve has closed.

The air tank valve 42 then may beheld open for a valve duration of 25 CA degrees or greater.
5

Preferably,
valve

the air tank valve

duration

of

50

CA

42 may be held open for

degreesorgreater.

aMore

preferably, the air tank valve 42 may be held open within arange of 25

to150 CA degrees,

during which time the airtank 40 is charged with compressed air.
10

During one complete crankshaft revolution in the
FC mode beginning with the intake stroke of the compression
piston20

andendingwith

theexhauststrokeoftheexpansion piston 30, the XovrC valve 24, the XovrE valve 26,
and
15

the

air

tank

valve

42

typically

sequence of openings and closings.

haveFirst,

thefollowing

the XovrC valve

24 opens and then the XovrE valve 26 opens.

The crossover

passage 22 is thereby pressurized with compressed air from
thecompression

cylinder

12,

and

the

compressed

air

is

transferred to the expansion cylinder 14.
20

Typically,

the

XovrC

valve

followed by the XovrE valve 26 closing.
engine operating conditions,

24

next,

However, under somethe XovrE valve

before the XovrC valve 24 closes.

closes

2 6 may close

In either case, an amountof excess compressed air is thereby trapped in the crossover
25

passage 22 between the closed XovrC and XovrE valves 24, 26.
The crossover passage 22 is over-pressurized such that thepressure

inthecrossoverpressure in the air tank 40.
opens and then later closes,
30

passage
Next,

isgreaterthanthethe air tank valve 42

allowing the excess compressed

air in the crossover passage 22 to flow into the air tank 40
due

to

the

pressuredifferential

passage and the air tank.

betweenthecrossoverwo 2011/115869

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21

However,atcertainengine(e.g., engine speed, engine load,

operatingconditions

air tank pressure,etc.),

the air tank valve 42 may open after the XovrE valve 26 has

5closed,but slightly before the XovrC valve 24 has closed.

In

case,

this

closings is:thesequential

orderof valve

XovrC valve 24 opens,

openings

andXovrE valve 26 opens,

XovrE valve 26 closes, air tank valve 42 opens, XovrC valve
24 closes,

and air tank valve 42 closes.

timing sequence,
10

are

open

the XovrC valve 24 and air tank valve 42

simultaneously

providing

fluid

Under this valveforcommunication

a

short

(i.e.,

period

of

time,

open

fluid

flow

an

path) between compression cylinder 12 and air tank 40.
Additionally,
be
15

20

controlledbyin the FC mode,varyingthetimingthe engine load may
of

the

XovrE

valve

closing to meter the needed amount of air into the expansion
cylinder required for

combustion.

exemplary embodiment,

the XovrE valve 26 may be closed at avalve

timingapproximately

ATDCe,as shown in FIG.

between

9.

As

Thus,

11

stated above,

and

23

CA

in an

degreesthe XovrE valve 2 6 only

lets into the expansion cylinder 14 the amount of compressedchargeair

neededclosing

when

the

for

the

desiredexpansion cylinder)load

requiredchargeamount(effectively
hasenteredbytheThe excess charge air remaining in the

crossover passage 22 is then stored in the air tank 40 as
25

described

above.

The

amountofcompressed

air

that

is

delivered to the air tank 40 during a single rotation of the
crankshaft 16(and thus the air flowrate into the air tank)

may be controlled by varying the timing of the intake valve
18
30

closing,whichcharge air drawn
exemplaryvalveeffectively

variesthetotalamount

of

into

the

compression cylinder 12.

In anembodiment,theintakeattiming between

valve

approximately

ATDCe as shown in FIG. 2.

103

18

is

and

140

closeda

CA degrees

wo 2011/115869

PCT/US2011/028278

22
FIGS.

2

through

11

graphicallyillustrateanexemplary embodiment of the FC mode of the split-cycle airhybrid engine

10 described above

over arange

of air tankpressures and air tank charging flowrates at an engine speed
5of 2000 rpm and an engine load of 2 bar IMEP.

In FIG. 2, theintake valve 18 is closed at a timing in the range of 103.0
to 140.0 CA degrees ATDCe.

For example,

at a tank pressureof 10 bar and an air tank flowrate of 3 g/s, the intake valve
18 is closed at approximately 122 CA degrees ATDCe.
10

3,

In FIG.

the intake valve 18 has a valve duration of between 56.5

and 93.5 CA degrees.

For example,

at a tank pressure of 10

barflowrate

3

and

an

air

tank

of

g/s,

the

intakevalve

duration is approximately 75 CA degrees.
In FIG. 4, the XovrC valve 24 has a valve duration
15

of between 3 6. 4 and 61. 8 CA degrees.

For example, at a tankpressure of 10 bar and an air tank flowrate of 3 g/s,
XovrC valve duration is approximately 45 CA degrees.
5,

20

the

In FIG.

the XovrE valve 2 6 has a valve duration of between 14.2

and 30.8 CA degrees.

For example,

at a tank pressure of 10

barflowrate

3

and

an

air

tank

of

g/s,

the

XovrE

valve

duration is approximately 26 CA degrees.
FIGS. 6 and 7 depict the XovrC valve 24 opening andclosing timings, respectively.

The XovrC valve 24 opens at atiming in the range of -23.20 to -9.79 CA degrees ATDCe and25

closes at a timing in the range of 24.6 to 38.6 CA degrees
ATDCe.
tank

For example, at a tank pressure of 10 bar and an air
flowrateapproximately

of

3

-17.5

g/s,

the

XovrC

CA

degrees

valve

ATDCe

and

24

opens

at

closesat

approximately 28 CA degrees ATDCe.
30

FIGS. 8 and 9 depict the XovrE valve 26 opening andclosing timings, respectively.

The XovrE valve 26 opens at atiming in the range of -1.62 to 14.00 CA degrees ATDCe andcloses at a timing in the range of 11.40 to 23.20 CA degrees

wo 2011/115869

PCT/US2011/028278

23

ATDCe.
tank

For example, at a tank pressure of 10 bar and an air
flowrateofapproximately

3

g/s,

-7.3

CA

the

XovrE

degrees

valve

ATDCe

26

and

opens

at

closesat

approximately 19 CA degrees ATDCe.
FIGS.

5
opening

and

10

and

closing11

depicttimings,

the

air

tank

valve

42

respectively.

The

air

tank

valve 42 opens at a timing in the range of 21.4 to 33.2 CA
degrees ATDCe and closes at a timing in the range of 131.4 to143.2 CA degrees ATDCe.
10

For example,

at a tank pressure of

10 bar and an air tank flowrate of 3 g/s, the air tank valve
42 opens at approximately 29 CA degrees ATDCe and closes atapproximately 139 CA degrees ATDCe.
As can be seen from FIGS. 9 - 11, over the range of
air tank pressures and air tank charging flowrates,

15

exemplary
degrees

embodiment

the

air

after the XovrE valve

valve closes

110 CA degrees

tankduration

valve

is

tank

valve

42

2 6 closes,

opens

10

CA

and the air tankafter it opens

substantiallyin this(i.e.,

fixed

the air

at

110

CA

degrees) .
The

20
valve

above

timingexemplary embodiment

sequenceforthe

FC modehas
ataillustrated asingleenginespeed and load (i.e., 2000 rpm at 2 bar IMEP).

However, one

skilled

FC

in

the

art

would

recognize

that

the

mode

may

operate over the entire speed and load range of the engine
25

10.

That is,the FC mode may operate from no-load to full-load and from idle speed to rated (full) speed of engine 10.
FIG.

12

graphicallyillustrates

the

fuel

(i.e.,

energy) penalty for compressing excess air in the compression30cylinder 12(for subsequently charging the air tank 40)

the

at

FC modean exemplary engine

engine load of 2 bar IMEP.

speed of 2000

inrpm and

The horizontal line at the bottomof the graph (air tank charging rate of 0 g/s) represents thefuel flowrate(in kg/hr)

when the air tank 40 is not being

wo 2011/115869

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24

charged(essentially the EF(or NF)

mode of the engine 10).

This is the zero fuel penalty baseline from which the fuelpenalty in the FC mode is calculated.

The three lines above

the horizontal baseline represent fuel expenditures in the FC
5mode at air tank charging rates of 1 g/s,

2 g/s,

and 3 g/s.

The fuel expenditures in the FC mode are,of course, greaterthan the fuel expenditure in the EF mode.

The fuel penalty

in the FC mode is calculated by subtracting the baseline fuelexpenditure from the fuel expenditure at a specific air tank10pressure and air tank charging rate.

For example, at an air

tank pressure of 5 bar and an air tank charging rate of 2g/s,

the fuel penalty

tank)

is approximately 0.09 kg/hr

g/s
15

minus

the

(extra energy spent to charge the airbaseline(1.11 kg/hr at 5 bar and 2

expenditure

of

1.02

kg/hr).

As

another example, at an air tank pressure of 10 bar and an air
tankcharging

rate

of

3

g/s,

the

fuel

penaltyisapproximately 0.35 kg/hr (1.37 kg/hr minus 1.02 kg/hr).
Althoughtheinventionreference to a specific embodiment,
20

has

been

described

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

concepts

described.

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

but that it have the full

language of the following claims.

scope defined by thewo 2011/115869

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25

CLAIMS

What is claimed is:
1.
5

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

compression
crankshaft

cylinder
such

that

pistonslidablyreceived

withinandoperatively

connected

tothecompression

pistonathe

reciprocatesthrough an intake stroke and a compression stroke during a10

single rotation of the crankshaft;anintake valve

selectively controlling air

flow

into the compression cylinder;
an

15

expansion

expansion

cylindercrankshaft

suchpistonandthat

slidablyreceived

withinanoperatively

connected

to

the

the

expansion

pistonreciprocatesthrough an expansion stroke and an exhaust stroke during asingle 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;ancrossover25

airreservoir

passageandoperatively

selectively

connected

operable

to

to

the
store

compressed air from the compression cylinder; andan air reservoir valve selectively controlling air
flow into and out of the air reservoir;
the engine being operable in a Firing and Charging
(FC)

30

mode, wherein,in the FC mode,

the air reservoir valve

is kept closed until the XovrE valve is substantially closed
duringasinglerotationofthecrankshaft

such

that

the

expansion cylinder is charged with compressed air before the
air reservoir is charged with compressed air.

wo 2011/115869

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262.
wherein,

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

in

the

FC mode,theairreservoir

valve

remains

closed in a range of from within plus or minus 5 degrees CA
of
5

when

the

XovrC

valve

opens

to

within

plus

or

minus

5

degrees CA of when the XovrE valve closes.
3.

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

wherein,in the FC mode,

position

5degreesCA

the air reservoir valve opens at aorgreater

after

the

XovrE

valve

closes.
104.
wherein,

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

in the FC mode,

position in a

range

the air reservoir valve opens at aof 5 -

2 0 degrees CA after the XovrE

valve closes.
5.
15

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

wherein,in the FC mode,

the air reservoir valve opens at a

position

less

than

degrees

6.

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

10

CA

after

the

XovrE

valve

closes.

wherein,
20

in

the

FC mode,theairreservoir valve

is

kept

open for a duration of 25 degrees CA or greater.
7.
wherein,in

The split-cycle air-hybrid engine of claim 1,
theFC mode,theairreservoir valve

is

kept

open for a duration of 50 degrees CA or greater.
8.
25

wherein,in

The split-cycle air-hybrid engine of claim 1,
theFC mode,theairreservoir valve

is

kept

open for a duration within a range of 25 degrees CA to 150
degrees CA.
9.
wherein,30

in

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

FC

mode,

engineload

iscontrolledbycontrolling the timing of XovrE valve closing.
10.
wherein,

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

in the FC mode,

an amount of excess compressed air

wo 2011/115869

PCT/US2011/028278

27
delivered to the air reservoir is controlled by controlling
the timing of intake valve closing.
11.
wherein,5

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

in the FC mode,the compression piston draws in andcompresses inlet air for use in the expansion cylinder,
compressed air
fuel,

at

the

is

admitted to

beginning

of

the

an

expansion

expansionandcylinder withstroke,which

isignited, burned and expanded on the same expansion stroke ofthe expansion piston,10

and thetransmitting power to the crankshaft,combustion products

aredischarged ontheexhauststroke.
12.

Amethodofoperatingasplit-cycle

air-hybrid engine including:a crankshaft rotatable about a crankshaft axis;
15

acompression

compression
crankshaft

cylinder
such

that

pistonslidablyreceived

withinandoperatively

connected

tothecompression

pistonathe

reciprocatesthrough an intake stroke and a compression stroke during asingle rotation of the crankshaft;20

anintake valve

selectively controlling air

flow

into the compression cylinder;
an

25

expansion

expansion

cylindercrankshaft

suchpistonandthat

slidablyreceived

withinanoperatively

connected

to

the

the

expansion

pistonreciprocatesthrough an expansion stroke and an exhaust stroke during asingle rotation of the crankshaft;a30

crossoverpassageinterconnecting

compression and expansion cylinders,theincludinga(XovrC)

crossover

expansion

crossoverchamber therebetween;compression(XovrE)

valve

the

crossover passage

defining

valve

and

a

a

pressurewo 2011/115869

PCT/US2011/028278

28ancrossoverairreservoir

passageandoperatively

selectively

connected

operable

to

to

the
store

compressed air from the compression cylinder; andan air reservoir valve selectively controlling air
5

flow into and out of the air reservoir;
the engine being operable in a Firing and Charging(FC) mode;the method including the steps of:drawing

10

andcompressing

inlet

air

with

the

compression piston;cylinder15inadmittingcompressed

intoexpansion

the

air

from

cylinder

the

with

fuel,

fuel

being ignited,

beginning of an expansion stroke,theburnedexpansion

andexpanded

expansion piston,the

combustion

on

same

the

the

transmitting power to the crankshaft,

and

being

discharged

strokeatofproducts

thecompression

on

the

exhauststroke; andkeeping the air reservoir valve closed until the
XovrE valve is substantially closed during a single rotation
20

of

the

chargedcrankshaft
with

such

compressed

that
air

the
beforeexpansion

cylinderisthereservoirisaircharged with compressed air.
13.

The method of claim 12, including the step of

keeping the air reservoir valve closed in a range of from25

within plus or minus 5 degrees CA of when the XovrC valve
opens to within plus or minus 5 degrees CA of when the XovrE
valve closes.
14.

The method of claim 12, including the step of

opening the air reservoir valve at a position 5 degrees CA
30

or greater after the XovrE valve closes.
15.

The method of claim 12, including the step of

opening the air reservoir valve at a position in a range of
5 - 20 degrees CA after the XovrE valve closes.

wo 2011/115869

PCT/US2011/028278

29
16.

The method of claim 12, including the step of

opening the air reservoir valve at a position less than 10
degrees CA after the XovrE valve closes.
17.
5

The method of claim 12, including the step of

keeping the air reservoir valve open for a duration of 25
degrees CA or greater.
18.
step

of

The method of claim 12, further including thecontrolling engine

load by varying

thetimingof

XovrE valve closing.
10

19.
step

of

delivered

The method of claim 12, further including thecontrollinganamountofexcesscompressed

air

to

reservoirbyvarying

the

of

the

air

intake valve closing.

timingwo 2011/115869

PCT/US2011/028278

1/12

FIG. 1

wo 2011/115869

PCT/US2011/028278

2/12

FIG. 2
AIR HYBRID-FIRING & CHARGING• Valve timings & durations at 2000 rpm 2 bar IMEPINLET CLOSING

5 r - - - - - - r - - - - - - r - - - - - : : : : : = : ; : ; : : ; M 1 100.0
2 105.03110.04 115.0--.
5 120.0
6 125.0.!:E.
40)
7 130.0(])
8 135.0........
9
140.0
co
I....
Max: 140.0~03~~'=-~~~;:::::;;;;~---~-r~s=:==::=l Min: 103.0
LL--I....

<(
~

c

~ 2

1

5

10
15
Tank Pressure (bar)20

wo 2011/115869

PCT/US2011/028278

3/12

FIG. 3
AIR HYBRID-FIRING & CHARGING• Valve timings & durations at 2000 rpm 2 bar IMEPINLET DURATION

5

1 55.02 60.03 65.04 70.0--.

5 75.0---8 90.04 ~=-~------~----------~--------~ 6 80.0
0)~7 85.09 95.0
Max: 93.5
Min: 56.5

I....

<(
~

c
~ 2 ~~~----~~----------~--------~

1 ~------~--~----------~--------~
10
15
20
5
Tank Pressure (bar)wo 2011/115869

PCT/US2011/028278

4/12

FIG. 4
AIR HYBRID-FIRING & CHARGING• Valve timings & durations at 2000 rpm 2 bar IMEP
XoverC DURATION

5 r - - - - - - . - - - . . , . - - - - r - - - - ; - - - - - - r - - - - - - - - , 1 35.0
2 39.03 43.04 47.05 51.0~ 4 1 - - - - - - + - - + - - - - - - + - - - - + - - - - - - ' t r - - - - - - - 1 6 55.0
0)
7 59.0
-8
63.0
(])
'§
Max: 61.8~
Min: 36.4
0

3 1----f----+-----f------+-----+-------1

LL
I....

<(
~

c

~2~-~;;;;;;;;;;;;;;;;;;::::::=-1---·-~-----~

1

5

10

15

Tank Pressure (bar)20

wo 2011/115869

PCT/US2011/028278

5/12

FIG. 5
AIR HYBRID-FIRING & CHARGING• Valve timings & durations at 2000 rpm 2 bar IMEP
XoverE DURATION

5

--.
~

4 ~----------+----+------~----------~

---

0)

(])

Max: 30.8
Min: 14.2........

coI....

~ 3 ~----------~------~~~----------~
LL
I....

<(
~

c

~

1 14.02 17.03 20.04 23.05 26.06 29.07 32.02 ~----------+-----------~-=~------~

1 ~----~----~--~----~~--~----~~
10
15
20
5
Tank Pressure (bar)wo 2011/115869

PCT/US2011/028278

6/12

FIG. 6
AIR HYBRID-FIRING & CHARGING• Valve timings & durations at 2000 rpm 2 bar IMEP
XoverC VALVE OPENING

1 -24.00
2 -22.00
3 -20.00
4-18.00
5-16.00
6 -14.00
7 -12.00
8-10.00
9 -8.00

5-----.

en

0)

4

(])

........

co

I....

Max: -9.79
Min: -23.20

~

0
LL

3

I....

<(
~

c

~

2

1

5

10
15
Tank Pressure (bar)20

wo 2011/115869

PCT/US2011/028278

7/12

FIG. 7
AIR HYBRID-FIRING & CHARGING• Valve timings & durations at 2000 rpm 2 bar IMEP
XoverC VALVE CLOSING

5
--.
~

---

0)

4 ~-----4----~----------~~~=---~

I....

<(
~

c

~ 2 r-----~~--r-----------r---------~

1 ~--~~--~~----~----~=-------~
10
15
20
5
Tank Pressure (bar)

1 24.02 26.03 28.04 30.05 32.06 34.07 36.08 38.09 40.0
Max: 38.6
Min: 24.6

wo 2011/115869

PCT/US2011/028278

8/12

FIG. 8AIR HYBRID-FIRING & CHARGING• Valve timings & durations at 2000 rpm 2 bar IMEP
XoverE VALVE OPENING

5-----.

en

0)

4

(])

........

co

Max: -1.62
Min : -14.00

I....

~

0
LL

3

I....

<(
~

c

~

1 -14.00
2 -12.00
3 -10.00
4 -8.00
5 -6.00
6 -4.00
7 -2.00
8 0.002

1 L_--------~~~~--~~~-=~~
10
15
20
5
Tank Pressure (bar)wo 2011/115869

PCT/US2011/028278

9/12

FIG. 9AIR HYBRID-FIRING & CHARGING• Valve timings & durations at 2000 rpm 2 bar IMEP
XoverE VALVE CLOSING

5

1 10.00
2 12.00
3 14.00
4 16.00
5 18.00
6 20.00
7 22.00
8 24.00
Max: 23.20
Min : 11.40

I

7
(])

~

........

~

I

~ 3

LL

•
~

I
1

5

( ( ~~~
10

15

Tank Pressure (bar)20

wo 2011/115869

PCT/US2011/028278

10/12

FIG. 10
AIR HYBRID-FIRING & CHARGING• Valve timings & durations at 2000 rpm 2 bar IMEP
• The air tank valve has the following characteristics at all conditions:0• Valve opens 10 after XoverE closing0• Duration is at 110
AIR TANK VALVE OPENING

5I

1 20.02 22.03 24.04 26.05 28.06 30.07 32.08 34.0
Max: 33.2
Min: 21.4

I

I

--.

!:E.
4
0)

---

7

(])

........

~

co

I....

~

0
LL

)

3

I....

•

<(
~

c

~ 2

I

1

5

I

~

( ~ ~~~
10
15
Tank Pressure (bar)20

wo 2011/115869

PCT/US2011/028278

11/12

FIG. 11
AIR HYBRID-FIRING & CHARGING• Valve timings & durations at 2000 rpm 2 bar IMEP
• The air tank valve has the following characteristics at all conditions:0• Valve opens 10 after XoverE closing0• Duration is at 110

5

AIR TANK VALVE CLOSING
I

I

1 130.0
2 132.0
3 134.0
4 136.0
5 138.0
6 140.0
7 142.0
8 144.0

I(])........

~
~

0
LL

Max: 143.2
Min: 131.4

3

)

I
1

5

(
10

l~~~

15
Tank Pressure (bar)20

wo 2011/115869

PCT/US2011/028278

12/12

FIG. 12
1.5

2000 RPM 2 bar,.,...~--.
I....

---..c0)~k-"""'~(]).......

co

..,.

1.4
................

...

~

t/

1.3

I....

~

0
LL
(])

1.2

:::J

LL

1.1

~~---~ ~"""........

,. ..,. .....

10

.A

~

~
5

..,.,

v

15

Tank Pressure (bar)

/I

20

•
0 g/s
............ 1 g/s--•-- 2 g/s_...__ 3 g/s

INTERNATIONAL SEARCH REPORTInternational application No.
PCT/US2011/028278

A.

CLASSIFICATION OF SUBJECT MATTER

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

FIELDS SEARCHED

Minimum documentation searched (classification system followed by classification symbols)
IPC( B)- F02B 3/00, 11100, 19/06, 33/00, 33/02, 33/06, 33/22, 41/02, 41/04, 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

--y
y

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 document

Relevant to claim No.
1-9,11-18-------10, 19

US 7,607,503 B1 (SCHECHTER) 27 October 2009 (27.10.2009) entire document

10, 19.

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

D*Special categories of cited documents:'T" later document published after the international filing date o~riority"A" document defining the general state of the art which is not considereddate and not in conflict with the ap~lication but cited to un erstandto be of particular relevancethe principle or theory underlying t e invention"E" earlier application or patent but published on or after the international "X" document of particular relevance; the claimed invention cannot be
filing dateconsidered novel or cannot be considered to involve an inventive
step when the document is taken alone"L" document which may throw doubts on priority claim(s) or which iscited to establish the publication date of another citation or other "Y"
document of particular relevance; the claimed invention cannot be
special reason (as specified)considered to involve an inventive step when the document is"0" document referring to an oral disclosure, use, exhibition or othercombined with one or more other such documents, such combination
means
being obvious to a person skilled in the art"P" document published prior to the international filing date but later than "&" document member of the same patent family
the priority date claimed
Date of the actual completion of the international search
01 May 2011
Name and mailing address of the !SAlUS
Mail Stop PCT, Attn: ISNUS, Commissioner for Patents
P.O. Box 1450, Alexandria, Virginia 22313-1450
Facsimile No. 571-273-3201
Form PCT/ISA/210 (second sheet) (July 2009)

Date of mailing of the international search report

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