(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/028286(22) International Filing Date:
14 March 2011 (14.03.2011)

WO 2011/115874 A1
West Sussex BN43 6WL (GB). GILBERT, Ian; 67
Beach Green, Shoreham-by-Sea, West Sussex BN43 5YE(GB).
(74) Agents: GAJEWSKI, Jeremy, 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,(8 4) Designated States (unless otherwise indicated, for every
kind of regional protection available): ARIPO (BW, GH,
GM, KE, LR, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG,
ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ,-- ------------------------------------------------------------------------------------------[Continued on next page](54) Title: SPLIT-CYCLE AIR-HYBRID ENGINE WITH MINIMIZED CROSSOVER PORT VOLUME

FIG. 1--;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;(57) Abstract: A split-cycle air-hybrid engine includes a rotatablecrankshaft. A compression piston is slidably received within a compression cylinder and operatively connected to the crankshaft. An expansion
piston is slidably received within an expansion cylinder and operatively
connected to the crankshaft. A crossover passage interconnects the compression and expansion cylinders. The crossover passage includes acrossover compression (XovrC) valve and a crossover expansion (XovrE)
valve defining a pressure chamber therebetween. An air reservoir is operatively connected to the crossover passage. An air reservoir port connects
the crossover passage to the air reservoir. An air reservoir valve is disposed in the air reservoir port. The air reservoir port includes a first air
reservoir port section between the crossover passage and the air reservoir
valve. The first air reservoir port section has a volume that is less than orequal to a volume of the crossover passage.

W 0 2011/11587 4 A1 11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK,
EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU,
LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK,
SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ,
GW, ML, MR, NE, SN, TD, TG).

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

wo 2011/115874

PCT/US2011/028286

1

SPLIT-CYCLE AIR-HYBRID ENGINE WITH MINIMIZED CROSSOVER PORT
VOLUMETECHNICAL FIELD

This invention relates to split-cycle engines and,more particularly,
5

tosuch 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 2011/115874

PCT/US2011/028286

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 2011/115874

PCT/US2011/028286

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 2011/115874

PCT/US2011/028286

4

Air

1)

Expandercompressed

(AE)

air

mode,

energy

which

from

includes

the

air

using

reservoir

without combustion;
2)
5

Air Compressor(AC)compressedenergyairmode,which includes

into

the

air

storing

reservoir

without combustion;
3)

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

4)Firingandstoring

Charging

compressed

(FC)
air

mode,

which

includesenergy

into

the

air

AE,

AC,

reservoir with combustion.
However,further

AEF and FC,
15

optimization of these modes,EF,

is desirable to enhance efficiency and reduce

emissions.

SUMMARY OF THE INVENTION

The present invention provides a split-cycle air20

hybrid engine

in which the

use

of

the

EngineFiring(EF)mode is optimized for potentially any vehicle in any drive
cycle for improved efficiency.
Moreparticularly,

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

invention includes a crankshaft rotatable about a crankshaft
axis.

A compression piston iscompression
crankshaft

cylinder
such

that

slidably received within aandoperatively

thecompression

connected
pistontothereciprocatesthrough an intake stroke and a compression stroke during a30

single rotation of the crankshaft.
slidablyreceived

operatively
expansion

withinconnected

pistonto

An expansion piston isanexpansionthecrankshaft

reciprocatesthroughancylinder
such

that

expansionandthestrokewo 2011/115874

PCT/US2011/028286

5

and

an

exhaustcrankshaft.

5

strokeAduringacrossoversinglepassagerotationoftheinterconnects

thecompression and expansion cylinders.

The crossover passage

includes(XovrC)acrossovercompression

crossover

expansion(XovrE)

chamber

therebetween.

An

valve
air

and

a

pressuredefining

reservoirconnected to the crossover passage.

valve

is

operatively

An air reservoir port

connects the crossover passage to the air reservoir.

10aAn airreservoir valve is disposed in the air reservoir port.

The

air

port

reservoir

portincludes

a

first

air

reservoir

section between the crossover passage and the air reservoir
valve.

The first

air reservoir port section has a volume

that

less

or

is

than

equal

to

a

volumeofthecrossoverpassage.
15

These

and

other

invention will be morefeaturesandadvantages

fully understood from the

of

the

followingdetailed description of the invention taken together with theaccompanying drawings.

20

BRIEF DESCRIPTION OF THE DRAWINGSIn the drawings:
FIG. 1 is a lateral sectional view of an exemplary
split-cycle air-hybrid engine in accordance with the present
25

invention.

DETAILED DESCRIPTION OF THE INVENTION

The following glossary of acronyms and definitions
30of terms used herein is provided for reference.

wo 2011/115874

PCT/US2011/028286

6

In General
Unless otherwise specified,closing timings

all valve opening andare measured in crank angle degrees

after

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

are in crank angle degrees
Air tank

specified,

all

valve

durations(CA) .

(or air storage tank): Storage tank for compressed

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

Bar: Unit of pressure, 1 bar

10 5 N/m 2

Compressor:

cylinderThe

compression

and

its

associatedits

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

expansion

cylinderandexpansion piston of a split-cycle engine.
15

Tank

valve:

Valve

connecting

the

Xovr

passagewith

thecompressed air storage tank.
Xovr

(or

Xover)

valve,

passage

or

port:

The

crossovervalves, passages, and/or ports which connect the compression
and20

expansion

cylindersthrough

which

gas

flows

from

compression to expansion cylinder.
XovrC(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.
25

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

The split-

cycle air-hybrid engine 10 replaces two adjacent cylindersofaconventional

enginewithacombinationofcompression cylinder 12 and one expansion cylinder 14.
30

one
A

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

14 to cover andwo 2011/115874

PCT/US2011/028286

7
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,
5

perform theintake(or inlet)

and the expansion cylinder 14,

and compression strokes,

together with its associatedexpansion piston30,

perform the

expansion(or power)

andexhaust strokes.

The Otto cycle is therefore completed inthese two cylinders 12, 14 once per crankshaft 16 revolution(360 degrees CA)
10

15

about crankshaft axis 17.

During the intake stroke,
drawn

into

port

19

the

compression

disposedintheintakecylindercylinder12(or inlet)
throughhead

33.

air isanAnintakeinwardly

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.
During20

piston20

chargeintothecompression

pressurizes
the

the

crossoverairstroke,chargepassage

the

and

(or

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 asourceofhigh-pressure

gas

to

the

crossoverpassage22,

which acts as the intake passage for the expansion cylinder
14.
25

In some embodiments,

interconnect thetwo or more crossover passages 22

compression cylinder

12

and theexpansion

cylinder 14.
The geometric30(or volumetric)

thecompression

cylinder

12

of

for

split-cycle

enginesingeneral)referred

to

as

the

"compression

engine.

The geometriccompression ratio ofsplit-cycle

ratio"(or volumetric)

engineisherein

of

the

(and

commonly

split-cycle

compression ratio of

the expansion cylinder 14 of split-cycle engine 10
split-cycle engines in general)

10(and foris herein commonly referredwo 2011/115874

PCT/US2011/028286

8

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 inthe5cylinderreciprocating

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.

defined10(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
15

1,

1,

40

to

greater)withinthecylinder12,anoutwardly opening(opening

outwardly away

from

the

cylinder)

valve

24

at

the

flow

from

control
20

crossover passage(e.g.,

20 to 1,

or

20 to

to

30

1,

(e.g.,

poppetcrossovercrossoverthe22.

passagecompression
Due

30 to 1,

to40

compression

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
passage 22 controls flow from the crossover passage 22 into
25

the expansion cylinder 14.

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

30

least 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
occursshortly before expansion piston 30

reachesits

topwo 2011/115874

PCT/US2011/028286

9

dead

centerposition.

The

air/fuel

chargeenterstheexpansion cylinder 14 when expansion piston 30 is close to
its

5

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
10

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
15

(TDC)

and 2 0 degrees

position.

throughwithAdditionally,

other

glow

CA past its

ignitionplugs,

combustion

devicesmicrowave

top deadand/ormaybemethods,

ignitiondevicesor

exhaust

gases

are

through compression ignition methods.
During20

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

cylinder 14 and the exhaust port 35.
25

and

the

exhaustpassage 22.
35 do

port

35

are

separate

The exhaust valve 34
from

the

crossoverThat is, exhaust valve 34 and the exhaust port

not makecontact with,or are not disposed in,thecrossover passage 22.
With the split-cycle engine concept, the geometric
30

enginelength,parametersvolumetriccompression

12

and

(i.e.,

bore,

stroke,connecting

rodcompression

ratio,

etc.)

the

expansion

independent from one another.

14cylindersareofgenerally

For example, the crank throws

wo 2011/115874

PCT/US2011/028286

10

36,

38

for

cylinder 14,

thecompression

cylinder12andexpansionrespectively, may have different radii and may

be phased apart from one another such that top dead center(TDC)
5of 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 reasons10

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 by

15

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
20

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
crankshaft
25

rotation)

during which

the

30

descends from its TDC position towards its BDC position andthecompression piston

2 0 simultaneously ascends

BDC position towards its TDC position.
time
26
30

expansion piston(or crankshaft rotation)

are

both

transferred

open,
( 1)

a

crossover passage 22 andtotheperiod,expansion

During the period of

equal

mass

of

compression cylinder 12(2)cylinderitsthat the crossover valves 24,

substantiallyfrom the

from

air

is

into

the

from the crossover passage 22
14.

Accordingly,

duringthisthe pressure in the crossover passage is prevented

wo 2011/115874

PCT/US2011/028286

11

from

dropping(typically

5

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
10

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 a15

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
20

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

25

As

discussed

disposedintheseparatefromearlier,theexhaust

port

of

the

cylinderpassage

22.

The

exhaustthecrossover35

arrangement of the exhaust valve 34
the crossover passage 22,

valve

34

is

head

33

structural

not being disposed inand therefore the exhaust port 35

notsharing any common portion with thecrossover passage

22,

is preferred in order to maintain the trapped mass ofgas in the crossover passage 22 during the exhaust stroke.
30

Accordingly,

large

cyclic drops

in pressure

are prevented

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

wo 2011/115874

PCT/US2011/028286

12
XovrE valve 26 opens shortly before the expansion
piston30

reaches

its

time,

the

pressure

topdead center position.

ratio

of

the

pressure

At

in

this

crossoverpassage 22 to the pressure in expansion cylinder 14 is high,5

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.

In other words,

when XovrE valve 26 opens, the pressure in crossover passage
10

22

is

substantially higher

cylinder 14
This

high

and/orpressurepressure

fuel

ratio

chargetocausesflow

initialinto

expansiontheitadvantageouscausessplit-cycle

pressuresofthecylinder

14

air
at

These high flow speeds can reach the speed ofparticularly

becausein expansion

flow

sound, which is referred to as sonic flow.
is

20

the

(typically in the order of 20 to 1 or greater).

high speeds.
15

than

even

a

to

This sonic flow

split-cycle

rapid combustion event,engine10

tothoughignitionmaintainisengine10

which enables

highcombustion

initiated

while

the

expansion piston 30 is descending from its top dead center
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
25

42.

(tank) valve

Embodiments with two or more crossover passages 22 may

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

or alternatively eachcrossover passage 22 may operatively connect to separate air
reservoirs 40.
30

The tank valve 42 is typically disposed in an air
reservoir(tank)

port

44,

which

passage

to

air

tank

40.

22

divided into a

the

first

extendsThe

air reservoir

air(tank)

fromcrossovertank port
port

44

is

section 46

wo 2011/115874

PCT/US2011/028286

13

and

a

secondair

reservoir(tank)

port

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
5

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.
The tank valve 42 may be any suitable valve device
10

or system.

For example, the tank valve 42 may be an active

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

pneumatic,

Additionally,

the tank valve

system with two
15

hydraulic,cam,electricorthelike).

42 may comprise a tank valve

or more valvesactuated with two

or moreactuation devices.
Air

tank

40

is

utilized to

store

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

power

the

crankshaft

16,

as

described

intheaforementioned United States Patent No. 7,353,786 to Scuderi
20

et al.

This mechanical means for storing potential energy

providesnumerous

potential

state of the art.

advantages

For instance,

over

the

current

the split-cycle engine 10

can potentially provide many advantages in fuel efficiency
gains
25

and

NOx

emissions

reductionatrelatively

lowmanufacturing and waste disposal costs in relation to othertechnologies

on

the

market,such

asdieselengines

andelectric-hybrid systems.
Byclosing30

ofselectively
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 10 is operable in an

Engine Firing

(EF)

mode,

an Air Expander

(AE)

mode,

an AirCompressor (AC) mode, an Air Expander and Firing (AEF) mode,wo 2011/115874

PCT/US2011/028286

14

and a Firing and Charging (FC) mode.

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

5

without the use of the air tank 40.

The AC and FC modes areenergymode

modes.

40

without

AC

combustion

cylinder14(i.e.,

utilizingthekinetic

engineduring braking.

10

is

an

air-hybridnooccurring

fuel

in

the

expenditure) ,energyexpansion

such

as

by
the

of

a

vehicleincluding

The

FC

mode

an

is

air-hybrid

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

than full engine load
at constant speed) .
mode
15

The

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

10

storagehas

an(e.g.,

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.

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 occurring
20

in the expansion cylinder 14
The

AEF

mode

is

an

(i.e.,

air-hybrid

no

fuel

operatingexpenditure).
mode

in

which

compressed air stored in the air tank 40 is utilized in the
expansion cylinder 14 for combustion.
In
25

order

to

avoid

significant

engine efficiency during the EF mode
which the air tank valve 42 isdeteriorationof the engine

kept closed,

in

10,

in

the first

airtank port section 46 has a volume that is less than or equal
to the volume of the crossover passage 22.

The volume of

the first air tank port section 46 includes the volume of30

all additional ports and recesses which connect the air tankvalve 42 to the crossover passage 22 when the air tank valve
is closed.

More specifically,

the volume of the first air

wo 2011/115874

PCT/US2011/028286

15

reservoir port section 46 may be less than or equal to 50%,
25%, or 10% of the volume of the crossover passage 22.
Althoughtheinventionreference to a specific embodiment,
5

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 2011/115874

PCT/US2011/028286

16
CLAIMS

What is claimed is:1.

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

5acompression

compression

cylindercrankshaft

such

that

pistonslidablyreceived

withinandoperatively

connected

tothecompression

through an intake stroke and a
10

pistonathe

reciprocatescompression stroke during asingle 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;acompression

20

crossoverpassageinterconnecting

and expansion

cylinders,theincludingacrossovercrossover

expansion

compression(XovrE)

valve

the

crossover passage(XovrC)

valve

and

a

pressuredefiningachamber therebetween;anairreservoir

operatively

reservoir

portconnected

tothecrossover passage;anairconnecting

thecrossoverpassage to the air reservoir; and
25

an

air

reservoir

valve

disposed

in

the

air

reservoir

portincluding

a

first

air

reservoir port;
the

air

reservoir port section between the crossover passage and the
air30

reservoir

valve,

thehaving a volume that is

first
less

air

reservoir port

sectionthan or equal to a volume of

the crossover passage.
2.

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

wherein the volume of the first

air reservoir port section

wo 2011/115874

PCT/US2011/028286

17

is less than or equal to 50% of the volume of the crossover
passage.
3.

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

wherein the volume of the first air reservoir port section
5is less than or equal to 25% of the volume of the crossover
passage.
4.

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

wherein the volume of the first air reservoir port sectionis less than or equal to 10% of the volume of the crossover
10

passage.
5.

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

wherein the volume of the first air reservoir port section
includes
which
15

the

volumeofconnect

the

air

all

additional

reservoir

valve

ports
to

and
the

passage when the air reservoir valve is closed.

recessescrossoverwo 2011/115874

PCT/US2011/028286

1/1

FIG. 1SUBSTITUTE SHEET (RULE 26)

INTERNATIONAL SEARCH REPORTInternational application No.
PCT/US2011/028286

A.

CLASSIFICATION OF SUBJECT MATTER

IPC(8)- F02B 33/22 (2011.01)
USPC- 123/70R
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{8) - F02B 33120, 33/22, 41/06 (2011.01)
USPC - 60/628; 123/62, 68, 70R, 70V
Documentation searched other than minimum documentation to the extent that such documents are included in the fields searchedElectronic data base consulted during the international search (name of data base and, where practicable, search terms used)
Pat Basec.

DOCUMENTS CONSIDERED TO BE RELEVANT

Category*

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

Relevant to claim No.

X

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

1-5

A

US 6,311,486 B1 (NEGREet al) 06 November 2001 (06.11.2001) entire document

1-5

D

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

Special categories of cited documents:"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
filing date"L" document which may throw doubts on priority claim(s) or which iscited to establish the publication date of another citation or otherspecial 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 thanthe priority date claimed"T'

Date of the actual completion of the international search

Date of mailing of the international search report

28 April 2011
Name and mailing address of the !SAlUS
Mail Stop PCT, Attn: ISAIUS, Commissioner for Patents
P.O. Box 1450, Alexandria, Virginia 22313-1450
Facsimile No. 571-273-3201
Form PCTIISN210 (second sheet) (July 2009)

later document published after the international filing date o7eriority
date and not in conflict with the apglication but cited to un erstandthe principle or theory underlying t e invention"X" document of particular relevance; the claimed invention cannot be
considered novel or cannot be considered to involve an inventive
step when the document is taken alone"Y" document of particular relevance; the claimed invention cannot be

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

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