IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIUS007536984B2(12~
United States Patent(Io) PatentNo.:(45)Date of Patent:

Lou

(54)

VARIABLE VALVE ACTUATOR WITH A
PNEUMATIC BOOSTER(75)

Inventor:(73)

Assignee: LGD Technology,LLC, Plymouth, MI(US)( * ) Notice:

Zheng Lou, Plymouth, MI (US)

Subject to any disclaimer, the term of thispatent is extended or adjusted under 35
U.S.C. 154(b) by 0 days.

(21)

Appl. No.: 11/787,295(22)

Filed:

Prior Publication Data
US 2008/0251041 Al

(52)
(58)

Oct. 16, 2008

Int. Cl.
F01L 1/34(2006.01)
U.S. Cl................
123/90.16; 123/90.15; 123/90.12
Field of ClassiTicationSearch .............. 123/90.11,
123/90.12, 90.16, 90.15; 137/906; 251/25;
91/356, 392, 508
See application file for complete search history.
References Cited(56)

U.S. PATENT DOCUMENTS
5,988,124A *6,543,225 B2
2005/0132987Al*

11/1999 Duesmann..
4/2003 Scuderi
6/2005 Chang ........

123/90.11
123/90.12

OTHER PUBLICATIONSSchuderi Group, L.L.C., Plaint' vs. LGD Technology,LLC and
Zheng(Davidl Lou, Ph.D., Defendents,Civil Complaint,U.S. District Court, District of Massachusetts.

* cited by examiner
Pri mary Examiner

Zelalem Eshete
ABSTRACT

Actuators, and corresponding methods and systems for controlling such actuators, provide independent valve control
with a large initial or opening force. In an exemplary embodiment, an actuator includes a driver further including a housing
defining a longitudinal axis and first and second directions, an
actuation mechanism capable of generating actuation force atleast in the first direction, and a rod with one end operablyconnected with at least one part of the actuation mechanism
and with the other end available for an operable connection
with a load such as an engine valve; at least one return spring
operably connected with the rod through a spring retainer
assembly and biasing the rod in the second direction; and apneumatic booster further including a pneumatic cylinder, apneumatic piston operably connected with the rod throughthe spring retainer assembly and biasing the rod in the first
direction, a charge mechanism providing a controlled fluid
communication between the pneumatic cylinder and a highpressure gas source, and a bleed mechanism providing acontrolled fluid communication between the pneumatic cylinder to a low-pressure gas sink.
15 Claims, 5 Drawing Sheets

116~i

90

L1

May 26, 2009

SchuderiGroup,LLC Plai ntig v. LGD Technology,
LLC and Zheng(DavidI Lou, Ph.D., Defendents,Answerto Complaint,Atfrrmative
Defenses,CounterclaimsandJury Demand.
Schuderi Group, LLC Plaint' v. LGD Technology,LLC and
Zheng(DavidI Lou, Ph.D., Defendents,Answer to Defendent's
CounterclaimandA15rmativeDefenses.

(57)

Apr. 16, 2007

(65)

(51)

US 7,536,984 B2

U.S.

PatentMay 26, 2009

Sheet

116

1 of

US 7,536,984 B2

5

30

90

FIGURE

1

U.S.

PatentMay 26, 2009

Sheet

US 7,536,984 B2

5

~ 30

116~~

Li

FlGURE

2 of

2

U.S.

PatentMay 26, 2009

Sheet

116

3 of

IJS 7,536,984 B2

5

30

90c

72
7
74

26

FlGURE

3

U.S.

PatentMay 26, 2009

Sheet

4 of

5

US 7,536,984 B2

~ 90d
72
7
74

26

FtGURE

4

U.S.

PatentMay 26, 2009

Sheet

5 of 5

US 7,536,984 B2

116

87

86b

82

26

FIGURE5

US 7,536,984 B2
1
VARIABLE VALVE ACTUATOR WITH A
PNEUMATIC BOOSTER

engine valves, the seating velocity of the cross-over valve has
to be kept under a certain limit to reduce noise and maintainadequate durability.

FIELD OF THE INVENTION
This invention relates generally to actuators and corresponding methods and systemsfor controlling such actuators,
and in particular, to actuators offering efficient, fast, flexible
control with large opening forces.
10

In summary, a cross-overvalve actuator has to offer a large
initial opening force, a substantial seating force, a reasonably
low seating velocity, a high actuation speed, and timing flexibility while consuming minimum energy by itself. Most, if
not all, conventional engine valve actuation systems are notable to meet these demands.

BACKGROUND OF THE INVENTION
SUMMARY OF THE INVENTION
A split four-stroke cycle internal combustion engine is
described in U.S. Pat. No. 6,543,225. It includes at least one
Briefly stated, in one aspect of the invention, one preferred
power piston and a corresponding first or power cylinder, and 15 embodiment of an actuator includes a driver further including
at least one compression piston and a corresponding second
a housing defining a longitudinal axis and first and secondor compression cylinder. The power piston reciprocatesdirections, an actuation mechanism capable of generating
through a power stroke and an exhaust stroke of a four-stroke
actuation force at least in the first direction, and a rod with one
cycle, while the compression piston reciprocates through an
end operably connected with at least one part of the actuation
intake stroke and a compression stroke. A pressure chamber 20 mechanism and with the other end available for an operable
or cross-over passage interconnects the compression andconnection with a load such as an engine valve; at least one
power cylinders, with an inlet check valve providing substanreturn spring operably connected with the rod through atially one-way gas flow from the compression cylinder to thespring retainer assembly and biasing the rod in the second
cross-over passage,and an outlet or cross-over valve providdirection; and a pneumatic booster further including a pneuing gas flow communication between the cross-over passage 25 matic cylinder, a pneumatic piston operably connected withand the power cylinder. The engine further includes an intake
the rod through the spring retainer assembly and biasing theand an exhaust valve on the compression and power cylinders,rod in the first direction, a charge mechanism providing a
respectively. The split-cycle engine according to the refercontrolled fluid communication between the pneumatic cylenced patent and other related developments potentiallyinder and a high-pressure gas source, and a bleed mechanism
offers many advantages in fuel efficiency, especially when 30 providing a controlled fluid communication between the
integrated with an additional air storage tank interconnectedpneumatic cylinder and a low-pressure gas sink.
with the cross-over passage,which makes it possible to operIn operation, the actuator holds the load to a second-direcate the engine as an air hybrid engine. Relative to an electricaltion end position with the force from the at-least-one return
hybrid engine, an air hybrid engine can potentially offer as
spring biasing in the second direction and overcoming themuch, if not more, fuel economy benefits at much lower 35 sum of the rest of the forces including those from the pneumanufacturing and waste disposal costs.
matic booster and the load, without generating the actuation
To achieve the potential benefits, the air or air-fuel mixture
force in the first direction from the actuation mechanism, andin the cross-over passagehas to be maintained at a predeterwith the pneumatic booster being charged through the charge
mined firing condition pressure, e.g. approximately 270 psi ormechanism to yield a substantial force in the first direction to18.6 bar gage-pressure, for the entire four stroke cycle. The 40 oppose a substantial load force in the second direction.
pressure may go much higher to achieve better combustion
The actuator initiates the travel of the load in the firstefficiency. Also, the opening window of the cross-over valve
direction by generating the actuation force in the first direchas to be extremely narrow, especially at medium and hightion from the actuation mechanism, with the combination ofengine speeds. The cross-over valve opens when the power
the actuation force and the force from the pneumatic booster
piston is at or near the top dead center (TDC) and closes 45 being able to overcome the sum of the rest of the forces
shortly after that. The total opening window in a split cycle
including those from the at-least-one return spring and theengine may be as short as one to two milliseconds, comparedload and accelerate the load in the first direction.
with a minimum period of six to eight milliseconds in a
The actuator keeps the travel in the first direction with theconventional engine. To seal against a persistently high presactuation force in the first direction until reaching the target
sure in the cross-over passage,a practical cross-over valve is 50
stroke, and keeping the actuation force in the first direction if
most likely a poppet or disk valve with an outward (Le. away
the load needs to be held at the target stroke. The actuatorfrom the power cylinder, instead of into it) opening motion.
initiates the return travel of the load in the second direction at
When closed, the valve disk or head is pressured against theleast by turning off the actuation force in the first direction sovalve seat under the cross-over passagepressure. To open thethat the load is accelerated in the second direction at least by
valve, an actuator has to provide an extremely large initial 55
the return spring.
opening force to overcome the pressure force on the head as
The actuator bleeds off excess air in the booster cylinderwell asthe inertia. The pressure force drops dramatically once
through the bleed mechanism during at least part of the time
the cross-over valve is open becauseof a substantialpressureperiod described in the above paragraph to reduce the force
equalization between the cross-over passage and the powercylinder. Once the combustion is initiated, the valve should be 60 from the pneumatic booster, which is otherwise too excessively resistant to the return travel of the load. It completes theclosed as soon as desired to prevent the spread of the comreturn travel with a decreasing force from the return spring
bustion into the cross-over passage,which also entails, during
and an increasing force from the pneumatic booster, whicha certain period of combustion, a needto keep the valve seatedhelp slow down the load.
against a power cylinder pressure that is higher than the
In another embodiment, the driver is a fluid driver, thecross-over passagepressure. In addition, the cross-over valve 65
needs to be deactivated when the power stroke is not active in
actuation mechanism comprising an actuation piston, an
actuation cylinder, first and second fluid spacesin fluid comcertain phases of the air hybrid operation. Like conventionalUS 7,536,984 B2
actuation 3-way valve 90, an return spring 72, and a pneumunication with first and second ports, respectively; and thematic booster S5. The load or control target of the actuator isrod being a piston rod operably connected with the actuation
piston and the load.
an engine valve 20.
The actuation 3-way valve 90 supplies the fluid driver 30
In another embodiment, the driver is an electromagnetic
driver; the actuation mechanism comprising an armature dis- 5 through a second port 62 of the fluid driver 30. The 3-way
valve 90 has two of its three ways connected with a lowposed in an armature chamber, and at least a first electromagpressureP Lfluidlineandahigh-pressureP
Hfluidline,andnet on the first direction side of the armature chamber,the third way connected with the second port 62. A first port
whereby being able to pull the armature in the first direction
60 of the fluid driver 30 is in fluid communication directly
when energized; and the rod being an armature rod operably
10 with the low-pressure P L fluid line.
connected with the armature and the load.
The actuation 3-way valve 90 is switched either to a left
In another embodiment, the charge mechanism includes a
position 92 or a right position 94. At the left and right posicharge orifice, whereby substantially restricting the charge
tions 92 and 94, the second port 62 is in fluid communication
flow rate. It may also includes a control mechanism thatwith the P H and P L lines, respectively.
substantially closes off charge flow at least when the bleed
15 The pressure P H can be either constant or continuously
mechanism is actively bleeding off excess air.
variable. When variable, it is to accommodate variability in
The present invention provides significant advantagesover
system friction, engine valve opening, air pressure, the engine
the prevailing fluid actuators and their control, especiallyvalve seating velocity requirement, etc., and/or to save operthose needed for the cross-over passage engine valve thatating energy when possible. The pressure P L can be simply
needs a large initial opening force, a substantial seating force,a reasonably low seating velocity, a high actuation speed,and 20 the fluid tank pressure, the atmosphere pressure, or a fluid
system backup pressure. The fluid system backup pressure
timing flexibility while consuming minimum energy by itself.
can be simply supported or controlled, for example, by a
The pneumatic booster is able to provide that large initialspring-loaded check valve, with or without an accumulator.
force, without adding too much construction complexity or
The P L value is preferred to be as low as possible to increasedemanding too much energy consumption or stretching thecapacity and functional limits of the fluid or electromagnetic 25 the system efficiency, and yet high enough to help prevent
fluid cavitation. When necessary,The P L can be more tightly
actuators, by tapping directly into the cross-over passage orcontrolled as well. When necessary and/or allowed, the two
the air storage tank. With the charge mechanism, the boost
P L lines connected with the two ports 60 and 62 may mainforce can be directly adjusted to the varying operating prestain two pressure values. For example, the first port 60 may be
sure in the cross-over passage, without sophisticated active
control. With the bleed mechanism, the engine valve return 30 simply used to dump some leakage flow to the fluid tank (notshown in FIG. 1). In this case, much of the first fluid spaceforce can be greatly reduced by making the boost force to be
may be simply filled with air, instead of the working fluid
substantially lower during the return stroke.
(assuming the working fluid is not air).
With the pneumatic booster, the driver, be it a fluid or
The engine valve 20 includes an engine valve head 22 andelectromagnetic one, is able to concentrate on more or lessconventional valve actuation, without the design, function 35 an engine valve stem 24. The engine-valve head 22 includes
a first surface 2S and a secondsurface 29, which in the caseof
and cost burden associated with the large initial opening
a split-cycle engine, are exposed to a cross-over passage 110
force, which conventionally entails large flow rate and packand the engine cylinder 102, respectively. The engine valve 20
age size for fluid drivers and high, if not impossible, magnetic
is operably connected with the fluid driver 30 along a longiforce and electrical power for electromagnetic drivers.
40 tudinal axis 116 through the engine valve stem 24, which is
The present invention, together with further objects andslideably disposed in an engine valve guide 120. For ease ofadvantages, will be best understood by reference to the foldescription, the assembly and the longitudinal axis 116 havelowing detailed description taken in conjunction with thefirst and second directions, which are the same as the top andaccompanying drawings.
bottom directions, respectively, in FIG. 1. The engine valve
45 guide 120 as illustrated in FIG. 1 does not look like a tradiBRIEF DESCRIPTION OF THE DRAWINGS
tional engine valve guide, which normally is a sleeve with amuch limited wall thickness. The guide 120 is designed to be
FIG. 1 is a schematic illustration of one preferred embodisituated in the cylinder head S2, over a valve assembly openment of the engine valve actuator, which is at a closed state;ing S3, which is large enough to slide through the engine
FIG. 2 is a schematic illustration of another preferred
50 valve head 22 during assembly. This is just one of many
embodiment, which includes design variations in the fluid
potential assembly options. This does not exclude the possidriver, the spring retainer assembly, and the pneumatic
bility of adding a traditional-looking sleeve inside the guidebooster;
120. The guide 120 may contain necessary engine coolant and
FIG. 3 is a schematic illustration of another preferredlubricant passages(not shown in FIG. 1).
embodiment, which includes a 3-way proportional valve and 55
When the engine valve 20 is fully closed, the engine valvea charge valve;head 22 is in contact with an engine valve seat 26, sealing off
FIG. 4 is a schematic illustration of another preferred
the fluid communication between the cross-over passage110
embodiment, which includes a 4-way proportional valve, aand the engine cylinder 102.
fluid driver with a double-ended piston rod, and a pneumatic
The fluid driver 30 comprises an actuator housing 70, an
booster without a bleed mechanism; and60 actuation piston 40, and an actuation cylinder 50. The actuaFIG. 5 is a schematic illustration of another preferredtion piston 40 is slideably disposed in the actuation cylinder
embodiment, which includes an electromagnetic driver.
50. The actuation piston 40 is fixed on to a piston rod 46
between a fastening element 45 and a shoulder 49. The actuaDETAILED DESCRIPTION OF THE INVENTION
tion piston 40 includes a first surface 42 and a secondsurface
65 44, and longitudinally divides the actuation cylinder 50 into afirst fluid space52 (between an actuation-cylinder first end 56
Referring now to FIG. 1, a preferred embodiment of theand an actuation-piston first surface 42) and a second fluid
invention provides an actuator including a fluid driver 30, an

US 7,536,984 B2
space54 (between the actuation-piston second surface 44 andtight seal between the first retainer 7S and the pneumaticthe actuation-cylinder second end 5S). The radial clearancescylinder S4 is kept only when the engine valve 20 is seated
and within a predefined distance L1 of the engine valve travel
around the actuation piston 40 and the piston rod 46 arein the first direction, beyond which there is a substantial
substantially tight, provide substantial fluid seal, and yet offer
tolerable resistance to relative motions.
5 clearance or bleed passage between the pneumatic cylinder
The second fluid space 54 is in fluid communication with
S4 and the first retainer 7S, and the pneumatic cylinder S4 isin substantial fluid communication with the atmosphere or athe second port 62 through a second flow passage 64 aroundlower-pressure gas sink and yet is in a restrictive fluid coma neck feature 4S on the piston rod. The second flow passage
64 becomes substantially more restrictive when the actuation
munication with the cross-over passage 110.
piston 40 is close to the actuation-cylinder second end 5S, 10 The actuation cylinder 50 offers substantial room longitudinally such that the actuation piston 40 does not touch thewith the shoulder 49 longitudinally approaching and/or overfirst and second ends 56 and 5S of the cylinder 50 when thelapping the second flow passage64. If a second flow mechaload or engine valve 20 is at its first-direction and secondnism is defined to include the second flow passage 64, theneck 4S, and the shoulder 49, then the second flow mechadirection end positions, respectively. When the engine valve
nism provides substantially open fluid communication 15 20 is seatedor at its second-direction end position as shown in
FIG. 1, there is still a distance between the actuation-piston
between the second; fluid space and the second port. It prosecond surface 44 and the actuation-cylinder second end 5S tovides a snubbing function when the actuation piston 40 isclose to the actuation-cylinder second end 5S. When desired,accommodate the engine valve lash adjustment. When thethe second flow mechanism may also include a one-way orengine valve 20 is fully open or at its first-direction end
check valve (not shown in FIG. 1), providing a parallel, sub- 20 position, there is enough force from the return spring 72
stantially-open fluid communication from the second port 62
and/or enough longitudinal spacein the cylinder 50 to preventa direct contact between the actuation-piston first surface 42
to the second fluid space 54.
and the actuation-cylinder first end 56.
The first fluid space 52 is in fluid communication with thefirst port 60 without much flow restriction.
Alternatively, one may design for the engine valve opening
The piston rod 46 is operably connected with the engine 25 travel to be limited or defined by the physical contact between
the actuation-piston first surface 42 and the actuation cylinder
valve stem 24, and in this embodiment (as illustrated in FIG.
first end 56, or between their equivalent surfaces, with nec1) the rod 46 and stem 24 are structurally the samepart, whichessary snubbing or control measures,like those shown later in
is not the only design option.
FIGS. 2 and 5.
A spring retainer assembly 74 is designed to help hold thereturn spring 72 and transfer its force on to the engine valve 30
The engine valve head 22 is generally exposed to the pressure of the cross-over passage 110 on the first surface 2S andstem 24. The return spring 72 as illustrated in FIG. 1 is a single
mechanical compression spring. This does not exclude otherthe pressure of the engine cylinder 102 on the second surface
29.
design options, such as a pair of compression springs in
The cross-section area of the first spring retainer or theparallel. The spring 72 may also be in the form of the
35 pneumatic: piston 7S is to be substantially equal to that of theBelleville type or pneumatic nature.
engine-valve head so that the pneumatic pressure force on the
The spring retainer assembly 74 includes a first and second
spring retainers 7S and SOand a set of valve keepers 76. The
pneumatic piston 7S substantially cancels the pressure force
on the engine-valve first surface 2S when the pressure in thefirst spring retainer 7S also functions or doubles as a pneupneumatic cylinder S4 is substantially equal to that in thematic piston, which is slideably disposed inside a pneumatic
cylinder S4, a cavity at the top of the engine valve guide 120, 40 cross-over passage, due to fluid communication through the
charge orifice S6. Alternatively, the cross-section area of theto form the pneumatic booster S5. The side, sliding walls of
the first spring retainer 7S and the pneumatic cylinder S4pneumatic piston 7S is to be appreciably, but not necessarily
maintain an air-tight seal and yet reasonable level of friction
substantially, different from, either larger or smaller than, thatwith necessary lubrication and sealing mechanism (detailsof the engine valve head 22. A larger pneumatic piston crossnot in FIG. 1). The return spring 72 and the pneumatic booster 45 section area, for example, offers an extra engine valve opening force so that a relatively more compact fluid driver 30 is
S5 apply forces to the first retainer 7S, and thus the engine
sufficient.
valve stem 24, in the second and first directions, respectively.
The system also experiences various friction forces,
The spring retainer assembly 74 is thus designed to sustain
steady-state flow forces, transient flow forces, and other inerforces in both directions. The force from the return spring 72
is applied to the first spring retainer 7S, and is transferred, 50 tia forces. Steady-state flow forces are caused by the hydrostatic pressure redistribution due to flow-induced velocity
through the valve keepers 76, to the engine valve stem 24. The
variation, i.e. the Bernoulli effect. Transient flow forces arepneumatic force from the pneumatic cylinder S4 is primarily
fluid inertial forces. Other inertial forces result from theapplied to the first spring retainer 7S, and is transferred to thevalve stem 24 through spring-retainer fastening means S1
acceleration of objects, excluding fluid here, with inertia, and(details of which are not illustrated in FIG. 1), the second 55 they are substantial in an engine valve assembly because of
the large magnitude of the acceleration or the fast timing.
spring retainer SO,and the valve keepers 76.
The pneumatic cylinder S4 is charged or supplied with thePower-Off State
pressurized gas or air from the cross-over passage 110, ahigh-pressure gas source, through a charge mechanism
including a charge passage 112 and a charge orifice S6. The 60 At power-off state, all fluid supply sources P H and P L
charge orifice S6 is designed to be more restrictive than theare at low or zero gage pressure. The total fluid force on theactuation piston 40 is substantially equal to zero. The engine
charge passage 112. The passage 112 and orifice S6 may be
combined into a single restrictive long orifice (not shown invalve can be seated or closed by the return spring 72 alone.
FIG. 1). The separate construction or existence of the charge
The seating is even more secureif the pneumatic piston 7S has
orifice S6 may ease the manufacturing process. The pneu- 65 a smaller diameter than the engine valve head 22, and thematic cylinder S4 is also intentionally designed to have ancross-over passage 110 is still sufficiently pressurized, espeexpansion 11S in its top portion so that a substantially aircially for an air-hybrid application with an air storage tank.

US 7,536,984 B2
At the power-off, the default position of the actuation
The engine valve 20 remains open as long as the actuation
3-way valve 90 is preferably, but not necessarily, to be in its
3-way valve 90 remains at its left position 92. During thisright position 94 as shown in FIG. 1 so that the second fluid
period, the pneumatic cylinder S4 keeps receiving a small
space54 is in fluid communication with the low pressure P L
stream of air flow from the charge orifice S6 and keeps bleedfluid line and is surely at a low or zero gagepressure i f a secure 5 ing the air out through the substantial gap between the pneuengine valve seating is important or critical. Immediately
matic piston 7S and its top, expanded cylinder wall 11S. This
after engine off, the high pressure P H fluid line may be stillenergy loss will continue until the pneumatic piston 7S is backpressurized. At the engine start, the engine valve 20 can beat the lower portion of the pneumatic cylinder S4. However,
kept at the closed position without actively switching thethe energy loss is minimized by the restrictive nature of the10valve 90.
charge orifice S6 and the limited engine valve opening period
Start-Uprelative to the entire thermal cycle.
To start closing the engine valve, the actuation 3-way valve
To start-up the system from the power-off state, all fluid
90 is switched to its right position 94, and the second fluid
supply sources are pressurized, and the actuation 3-way valve
15 space 54 is open back to the low pressure P L fluid supply,
90 is secured, either by default or active control, at its right
resulting in a substantially zero pressure differential acrossposition 94 as shown in FIG. 1. The engine valve 20 is
the actuation piston 40. The return spring 72 is able to drive
secured, at least by the return spring 72, at the closed or seatedthe engine valve 20 downward. When the pneumatic piston 7S
position as shown in FIG. 1.
passesthe expanded part 11S of the pneumatic cylinder S4, a
20 substantially air-tight seal is established again between the
Valve Opening and Closing
pneumatic piston 7S and the wall of the pneumatic cylinder
To open the engine valve 20, the actuation 3-way valve 90
S4, and the pressure in the pneumatic cylinder starts building
is switched to its left position 92. The second fluid space54 is
up primarily because of a shrinking cylinder volume as theopento the highpressure P H supply throughthe second flo
engine valve 20 and thus the pneumatic piston 7S move downmechanism, while the first fluid space 52 remains to be 25 ward. The pressure build-up is also assisted by the flow fromexposed to the low pressure P L supply. The resulting differthe charge orifice S6. The pneumatic cylinder S4 functions
ential pressure force on the actuation piston 40 is in the first
like a pneumatic spring, slowing down the advancement of
direction (or upward in FIG. 1) to overcome primarily thethe engine valve 20 and eventually helping achieve a softspring force, driving open the engine valve 20. At the same
seating when the engine valve 20 reaches the engine-valvetime, the downward differential air pressure force on the 30
seat 26.
engine valve 20 is substantially balanced by the upward difAround the engine valve seating or landing and shortly
ferential air pressure force on the pneumatic piston 7S, conafter that, the pressure in the engine cylinder momentarilysidering that the pneumatic cylinder S4 is under the same
exceedsthe cross-over passagepressure because of the effectpressure as the cross-over passage 110. In a split-cycle
engine, the dominant force on an engine valve is the air 35 of the combustion, resulting in a transient differential pressure force in the first direction or upward. The preload of thepressure force from the cross-over passage110. The incorporeturn spring 72 should be designed to be able to hold theration of the pneumatic piston 7S helps balance out andengine valve 20 in seated position against this transientcounter this large force, which otherwise demands an
upward differential force on the engine valve and also against
extremely large and energy-intensive actuator.
As soon as the engine valve 20 cracks open, the engine 40 the pressure force from the pneumatic cylinder S4. The pneumatic cylinder pressure, at this moment, is however not equal
cylinder 102 is filled rapidly, and its pressure reaches theto the full cross-over pressure. It is purposely so by earlier
cross-over passage pressure within a short period of time,
bleeding off through the expanded portion 11S of the pneuwell before the engine valve 20 passesthe middle point of thematic cylinder S4 and the restrictive nature of the charge
opening stroke, resulting in a rapid disappearance of the diforifice S6.
ferential pressure on the engine valve surfaces 2S and 29. 45
Thereafter, the engine cylinder pressure drops below theDuring the same short period of time, the pressure in the
cross-over passage pressure as the volume expands further.
pneumatic cylinder S4 and the differential pressure on the
The pneumatic cylinder pressure rises up further through thepneumatic piston 7S drop rapidly as well because of its limrestricted flow from the charge orifice S6 during the rest of theited, predefined initial volume, its rapid volume expansion
associatedwith the engine valve movement, a limited amount 50 engine thermal cycle, which is slow but sure enough to beready for the next engine valve opening event.
of air inflow through the charge orifice S6, and the bleeding
FIG. 2 depicts an alternative embodiment of the inventiono ff of the air asthe pneumatic piston 7S moves up a predefinedthat features some variations in the design of the fluid driver
distance L1, as shown in FIG. 1, to the expanded top portion
30. The first flow mechanism, which is the means of the fluid
11S of the pneumatic cylinder S4.
For the rest of the opening stroke or beyond the distance 55 communication between the first port 60 and the first fluid
space 52, includes a first undercut 32 and at least one first
L1, the air pressure forces on the pneumatic piston 7S and thesnubbing groove 33. When the actuation-piston first surface
engine valve 20 are minimum, and the actuation piston 40
continues to drive the engine valve 20 in the first direction (or42 passes the first undercut 32 longitudinally in the first
direction during an opening stroke, the working fluid is subupward in FIG. 1) against an increasing spring force from thereturn spring 72 until the engine valve reaches its full open 60 stantially trapped in the first fluid space 52, with only alimited outlet through the at-least-one first snubbing groove
position, when the spring force and the fluid differential force
acrossthe actuation piston 40 are balanced, which is expected
33, resulting in a snubbing action to help slow down the travel
speed and reduce potential oscillation. When so desired, theto be dynamic with certain overshoot and damped oscillation,
considering the spring-mass nature of the construction. Thereactuation-cylinder first end can be longitudinally arranged toare however measures, as shown in other preferred embodi- 65 provide a solid stop to the actuation-piston first surface 42,thus a well defined engine valve lift. If so desired, a checkments (FIGS. 2 and 4), to have a more definitive lift or fullvalve (not shown in FIG. 2) can be arranged to allow one-way
open position.

US 7,536,984 B2
10flow from the first port 60 into the end of the first fluid space
the fluid supply to the second fluid space54. The engine valve
or actuator position signal can be collected via a position
52 during the starting phase of the engine valve closing stroke
to avoid cavitation.
sensor (not shown in FIG. 3). The feedback control will help
achieve more precise control over the engine valve lift and
Similarly, the second flow mechanism, which is the meansof fluid communication between the second port 62 and the 5 seating velocity. The proportional or servo valve 90c itself cansecond fluid space 5S, includes a second undercut 34 and at
be actuated directly via various means (not shown in FIG. 3),
least one second snubbing groove 35. When the actuationincluding solenoids or other electromagnetic means, electropiston second surface 44 passesthe second undercut 34 lonhydraulic pilot valves, and piezoelectric actuators.
This embodiment further features a charge valve 10S, as a
gitudinally in the second direction during an closing stroke,
the working fluid is substantially trapped in the second fluid 10 control mechanism, along the charge passage 112 to help
space 5S, with only a limited outlet through the at-least-one
achieve better control over the charging process for the pneumatic cylinder S4. The charge valve 10Shas at least one of two
second snubbing groove 35, resulting in a snubbing action to
help slow down the travel speed and achieve soft-seating for
major functions: (I) to open the charge passage112, allowing
the engine valve 20. It is desired to leave a predefined longithe pneumatic cylinder S4 to be charged, before the engine
tudinal distance between the actuation-cylinder second end 15 valve opening stroke, and close the charge passage112 espeand the actuation-piston second surface 44 to ensure a solid
cially if the restrictive charge orifice S6 is not used, eliminatcontact and tight seal between the engine valve head 22 anding or reducing leak flow when the pneumatic cylinder S4 isthe valve seat 26 when the engine valve 20 is seated, whichbeing bled; (2) to completely close off the charge passage112
has to be accommodated at all engine operating conditions
when the engine or that particular engine cylinder is powerand throughout the engine's service life. When necessary, 20 off, as in an air hybrid vehicle, minimizing leakage and preadditional engine valve lash adjustment device (not shown inserving the pressurized air in the cross-over passage and/or
FIG. 2) is to be integrated in this and other embodiments.
the air storage tank. For the first function, one charge valve
The embodiment in FIG. 2 further features variations in the
10S is needed for each power cylinder of the split four-stroke
cycle engine because each power cylinder has its uniquedesign of the spring retainer assembly 74. The second spring
retainer SO,instead of the first spring retainer 7S, functions or 25 timing. If only the secondfunction is needed, one may optiondoubles as the pneumatic piston SO.It also includes two sets
ally use only one charge valve 10S for an entire engine, withof valve keepers 76b and 76c. This embodiment allows thethe valve 10S controlling a common charge passage (notshown in FIG. 3) that eventually branches into tributaryengine valve stem 24 and the piston rod 46 to be physicallycharge passages (not shown in FIG. 3) for individual power
two separate pieces, united operably by the spring retainer
assembly 74 with necessary fastening means 106 or the 30 cylinders (not shown in FIG. 3). Further for the first function,equivalent.
the charge valve 10S may be optionally a proportional valve,This embodiment also shows variations in the charging andinstead of an on/off valve. By being a proportional valve, thebleeding mechanisms for the pneumatic booster S5. It adopts
charge valve 10S is able to actively control, for example, theair pressure in the pneumatic cylinder S4 for various funcat least one bleed hole S7 as the bleed passage,instead of an
expanded wall 11S in FIG. 1, for the pneumatic cylinder S4 to 35 tional, durability and NVH needs.
discharge its extra gas when the pneumatic piston SObtravels
At this and other figures, the charge passage 112 is conup a predefined distance L1 as shown in FIG. 2. The bleed
nected to the cross-over passage 110. Optionally, it can beconnected to the air storage tank (in the case of an air hybrid
holes S7 may be fitted with porous materials or filters (notshown) to reduce noise associated the bleeding process. To
vehicle) or a separatereservoir (not shown in the figures). The
save the effort and cost of drilling or casting the bleed holes 40 separatereservoir may have its own pressure, which may beregulated to help achieve optimum charging process for the
S7, one may also simply design the engine valve guide 120,
pneumatic cylinder S4.
and thus the pneumatic cylinder S4, up to that height, causing
Refer now to FIG. 4, which is a drawing of yet anotherthe pneumatic piston SObto be disengaged from the pneualternative embodiment of the invention. In this case, a promatic cylinder S4 once it travels up to that point, resulting in
45 portional or servo 4-way valve 90d is used to control the fluid
a wide open bleeding process.
One can also use some predefined variation (not shown insupply both to the first and secondfluid spaces52 and 54. This
embodiment is able to provide actively-controlled actuation
FIG. 2) in the radial clearance between the pneumatic piston
forces both in the first and second directions. Optionally, theSOb and the pneumatic cylinder S4. Adopting an opposite
piston rod 46 extends longitudinally through the first fluid
approach, some diaphragm (not shown in FIG. 2) may be used
to completely seal off leakage through the radial clearance, 50 space 52, becoming a double-ended piston rod. To have a
totally depending on the at-least-one bleed hole S7 or its
biased or asymmetric differential fluid force, the two ends ofequivalent for the control of the air or gas mass discharge.
the piston rod may possesstwo different diameters, with theside with a smaller rod diameter having a larger effective fluid
Also, when desired, one may use a control valve (not shownin FIG. 2) to control its on/off state.
pressure surface area.
Still another variation or option is its lack of a bleedmechaThe charge orifice S6b in FIG. 2 is regulated by a control 55
nism. The actuation force in the second direction will easily
mechanism including an orifice gate S9 and a stem undercut
104, which are not open to each other when the engine valve
help overcome the high air pressure force from the pneumatic
booster S5 during the engine valve closing. The elimination of
20 travels up a predefined distance L2 (as shown in FIG. 2).
the bleed mechanism will help simplify the construction of
The distance L2 is preferably to be equal or shorter than the
distance L1 so that the flow through the charge orifice S6b and 60 the pneumatic booster S5. Without a bleed mechanism orthus the charging process are substantially blocked when thesubstantial leakage, the charge mechanism, including thecharge orifice S6, is still needed to compensate for potential
discharging process, through the bleed hole S7 or its equivalent, is active. This variation in the charge mechanism will
minor leakages, and adjust the pressure and air mass level inthe pneumatic booster S5 to accommodate the pressure level
help reduce unnecessary,however small, energy loss.
Refer now to FIG. 3, which is a drawing of yet another 65 variation in the cross-over passage or air storage tank. The
alternative embodiment of the invention. In this fluid driver
actuator needs a lower boost force, for example, when the
30, a proportional or servo 3-way valve 90c is used to control
cross-over passagepressure is lower. In this sense,the charge

US 7,536,984 B2
12mechanism also has a balancefunction, which is even true forfrom the pneumatic booster during the engine valve closing,
the pneumatic boosters with a bleed mechanism.
when there is no high differential air pressure force on theengine valve to balance the force from the pneumatic booster.
Depending on the application, the rest of the embodiment
In FIGS. 1-5, various embodiments of the pneumaticin FIG. 4 may still be integrated with one of the bleed mechanisms featured in earlier embodiments (illustrated in FIGS. 5 booster S5 are specially developed to overcome the initialpressure force on the engine-valve first surface 2S to crack
1-3) if a lower air pressure force is ideal for the engine valve
open the engine valve. Yet, through its bleed mechanism, theseating process.
pneumatic booster S5 is able to scale down its pressure force
Refer now to FIG. 5, which is a drawing of yet anotheralternative embodiment of the invention. In this embodiment,
for the valve closing when the differential pressure force
an electromagnetic driver 130 replaces the fluid drivers 30 in 10 acrossthe engine valve head is substantially smaller. With thispneumatic booster S5, the fluid drivers 30 in FIGS. 1-4 and the
FIGS. 1-4. The electromagnetic driver 130 includes a housing
electromagnetic driver 130 in FIG. 5 are able to handle the132, within which from the top to the bottom are a firstelectromagnet 134, an armature chamber 146, and a second
less forceful part of the engine valve opening and closing. The
effective integration of the various embodiments of the pneuelectromagnet 136. The first and second electromagnets 134
and 136 further include their electrical windings and lamina- 15 matic booster S5 is not limited to those fluid and electromagtion stacks, details of which are not shown in FIG. 5. An
netic drivers 30 and 130 discussed above. In fact, any driverwith sufficient force and control for the engine valve accelarmature 13S is disposed inside the armature chamber 146
and between the first and second electromagnets 134 and 136
eration, deceleration, and seating control will do, with theand is rigidly connected to an armature rod 140. The armaturelarge initial opening force being taken care of by the pneurod 140 is slideably disposed through the second electromag- 20 matic booster S5.
net 136 and the housing 132, and is operably connected withIn all the above descriptions, each of the switch and/or
the engine valve stem 24.
control valves may be either a single-stagetype or a multipleWhen powered, the first and second electromagnets 134
stage type. Each valve can be either a linear type (such as aand 136 attract the armature 13S in the first (top) and second
spool valve) or a rotary type. Each valve can be driven or(bottom) directions, respectively. The first electromagnet 134 25 piloted by an electric, electromagnetic, mechanic, piezoelecis able to catch the armature 13S and keep the engine valve 20
tric, or fluid means.
open at the full lift. To crack open the engine valve 20 when
In some illustrations and descriptions, the fluid medium
the air pressure forces on the engine valve 20 and the pneumay be assumed or implied to be in hydraulic or in liquid
matic piston SOare substantially balanced, the first electroform. In most cases,the same concepts can be applied, withmagnet 134 only needs to overcome the preload from the 30 proper scaling, to pneumatic boosters and systems. As such,
return spring 72, which is achievable despite the highly nonthe term "fluid" asused herein is meant to include both liquids
linear nature of the electromagnetic force becausethe overall
and gases.Also, in many illustrations and descriptions so far,lift for the cross-over engine valve and thus the air gap
the application of the invention is defaulted to be in split
between the armature 13S and the electromagnet 134 are
four-stroke cycle internal combustion engine valve control,
small. This can be further assisted, if necessary,by designing 35 and it is not limited so. The invention can be applied to otherthe pneumatic piston SO to be appreciably larger than thesituations where a fast and/or high-initial-force control of theengine valve head 22 and thus introducing a differential air
motion is needed.
pressure force in the first direction.
Although the present invention has been described with
To close the engine valve 20 from the full open position, thereference to the preferred embodiments, those skilled in thefirst electromagnet 134 is de-energized, and the engine valve 40 art will recognize that changes may be made in form and
20 is pushed down by the returning force of the return springdetail without departing from the spirit and scope of the72, with the pulling assistance, if necessary, from an enerinvention. As such, it is intended that the foregoing detailed
gized second electromagnet 136. During the later phase of thedescription be regarded as illustrative rather than limiting andclosing, the pneumatic cylinder S6 is pressurized by volumetthat it is the appended claims, including all equivalents
ric contraction and optional charging action through the 45 thereof, which are intended to define the scope of this invencharge orifice S6b, and it helps slow down the engine valve 20
tion.
to achieve soft-seating. A further retarding action can be
I claim:achieved by re-energizing the first electromagnet 134 in a
1. An actuator, comprising
controlled way, resulting in a desired pulling force in the firsta fluid driver including a housing defining a longitudinal
direction depending on the operational needs or feedback 50
axis and first and second directions, an actuation mechasignal.
nism comprising an actuation cylinder and an actuation
The pulling force in the second direction from the second
piston slideably disposed in the actuation cylinder, withelectromagnet 136 may also assist the return spring 72, if a
the actuation mechanism generating actuation force at
low spring preload is desired otherwise, in keeping the engine
least in the first direction;
valve 20 seated during at least part of combustion, when the 55
at least one return spring operably connected with thepressure in the power cylinder 102 appreciably exceeds that
actuation mechanism and biasing the actuation mechain the cross-over passage110.
nism in the second direction; andIf the pneumatic booster S5 includes a bleed mechanism
a pneumatic booster operably connected with the actuation
like the bleed holes S7 in FIG. 5, the second electromagnet
mechanism and biasing the actuation mechanism in the
136 is an optional component, which can be eliminated if the 60
first direction, whereby giving the driver a boost force inreturn spring 72 and other related components are sufficientthe first direction; and wherein:
for various functions.
the pneumatic booster further including a pneumatic cylThe second electromagnet 136 is indispensable, however,
if one is to adopt a pneumatic booster design without, as
inder; a pneumatic piston, slideably disposed in theshown in FIG. 4, a bleed mechanism. In this case, the second 65
pneumatic cylinder for at least part of its travel range;electromagnet 136 needs to generate an actuation force in theand a charge mechanism, whereby charging the pneusecond direction to help overcome a high air pressure force
matic cylinder and balancing its pressure with pressur-US 7,536,984 B2
13
ized air from a high-pressure gas source during at least
part of an actuation cycle of the actuator;
the charge mechanism including a control mechanism,
whereby substantially closing off the charge flow duringa substantial portion of a period when the pneumatic 6
cylinder is not at its minimum volume;
the actuation mechanism being operably connected with aload of the actuator through a stem;
the control mechanism of the charge mechanism including
an orifice gate and an undercut on the stem; and10
the charge flow being open and closed when the orifice gate
and the undercut longitudinally overlap and underlap
respectively.
2. An actuator, comprisinga fluid driver including a housing defining a longitudinal t6
axis and first and second directions, an actuation mechanism comprising an actuation cylinder and an actuation
piston slideably disposed in the actuation cylinder, withthe actuation mechanism generating actuation force atleast in the first direction;
20
at least one return spring operably connected with theactuation mechanism and biasing the actuation mechanism in the second direction; anda pneumatic booster operably connected with the actuation
mechanism and biasing the actuation mechanism in the 26
first direction, whereby giving the driver a boost force inthe first direction; and wherein:
the pneumatic booster further including a pneumatic cylinder; a pneumatic piston, slideably disposed in thepneumatic cylinder for at least part of its travel range; 30
and a charge mechanism, whereby charging the pneumatic cylinder and balancing its pressure with pressurized air from a high-pressure gas source during at least
part of an actuation cycle of the actuator;
the pneumatic booster further including a bleed mecha- 36
nism, whereby bleeding off excess air from the pneumatic cylinder to a low-pressure gas sink during at least
part of an actuation cycle of the actuator; andthe bleed mechanism being at least one bleed passage,
which becomes substantially exposed to the pressurized 40
air in the pneumatic cylinder when the pneumatic piston
travels beyond a predefineddistance from an initial position, whereby bleeding off excess air.
3. An actuator, comprisinga fluid driver including a housing defining a longitudinal 46
axis and first and second directions, an actuation mechanism comprising an actuation cylinder and an actuation
piston slideably disposed in the actuation cylinder, withthe actuation mechanism generating actuation force atleast in the first direction;60
at least one return spring operably connected with theactuation mechanism and biasing the actuation mechanism in the second direction; anda pneumatic booster operably connected with the actuation
mechanism and biasing the actuation mechanism in the 66
first direction, whereby giving the driver a boost force inthe first direction; and wherein:
the actuation piston dividing the inner volume of the actuation cylinder into first and second fluid spacesand being
operably connected with a piston rod; and60
the actuation mechanism further comprising first and second ports in fluid communication with the first and second fluid spaces,respectively.
4. The actuator of claim 3, wherein
the second port being alternately supplied with high-pres- 66
sure and low-pressure fluid lines, through an actuation
3-way valve.

14
5. The actuator of claim 3, wherein
the second port being supplied through a proportional
3-way valve.
6. The actuator of claim 3, wherein
the first and second ports being supplied through a 4-way
valve.
7. A method of controlling an actuator comprising:(a) providing an actuator including the following components:a driver further including
a housing defining a longitudinal axis and first and second directions,an actuation mechanism capable of generating actuation
force at least in the first direction, anda rod with one end operably connected with at least one
part of the actuation mechanism and with the otherend available for an operable connection with a loadof the actuator;
at least one return spring operably connected with the rod
and biasing the rod in the second direction; anda pneumatic booster further including
a pneumatic cylinder,a pneumatic piston operably connected with the rod andbiasing the rod in the first direction, anda charge mechanism, whereby providing a controlled
fluid communication between the pneumatic cylinderand a high-pressure gas source;(b) holding the load of the actuator to a second-direction
end position
with the force from the at-least-one return spring biasing inthe second direction and overcoming the sum of the restof the forces including those from the pneumatic booster
and the load,
without generating the actuation force in the first direction
from the actuation mechanism, andwith the pneumatic booster being charged through the
charge mechanism to yield a substantial force in the first
direction to oppose a substantial load force in the second
direction;(c) initiating the travel o fthe load o fthe actuator in the first
direction by generating the actuation force in the first
direction from the actuation mechanism, with the combination of the actuation force and the force from thepneumatic booster being able to overcome the sum of therest of the forces including those from the at-least-one
return spring and the load and accelerate the load in thefirst direction;(d) continuing the travel in the first direction with theactuation force in the first direction at least until reaching the target stroke;(e) initiating the return travel of the load of the actuator in
the second direction at least by turning off the actuation
force in the first direction so that the load is accelerated
in the second direction at least by the return spring;(fI completing the return travel with a decreasing force
from the return spring and an increasing force from thepneumatic booster, whereby slowing down the load.
S. The method of claim 7, wherein:
the pneumatic booster further including a bleed mechanism, whereby providing a controlled fluid communication between the pneumatic cylinder and a low-pressure
gas sink.
9. The method of claim S, further comprising
bleeding off excess air in the booster cylinder through the
bleed mechanism, during at least part of the time period
after the initial travel in the first direction and before nearUS 7,536,984 B2
1516
the close of the travel in the second direction, to reduce
cylinder and dividing the inner volume of the actuation
the force from the pneumatic booster.
cylinder into first and second fluid spaces, and first andsecond ports in fluid communication with the first and10. The method of claim 7, wherein:second fluid spaces,respectively; andthe charge mechanism including a charge orifice, whereby
5
the rod being a piston rod operably connected with thesubstantially restricting the charge flow rate.
actuation piston.
11. The method of claim 7, wherein:
14. The method of claim 7, wherein
the charge mechanism including a control mechanism,
the driver being an electromagnetic driver;whereby substantially closing off the charge flow during
the actuation mechanism comprising an armature chamber,a substantial portion of a period when the pneumatic
10
an armature disposed in the armature chamber, and at
cylinder is not at its minimum volume.
least a first electromagnet on the first direction side of the
12. The method of claim S, wherein:
armature chamber, whereby being able to pull the armathe bleed mechanism being at least one passage, which
ture in the first direction when energized; andbecomes exposed to the pressurized air in the pneumaticthe rod being an armature rod operably connected with thecylinder when the pneumatic piston travels beyond aarmature.
predefined distance from an initial position, whereby
15. The method of claim 14, further including a second
bleeding off excess air.
electromagnet on the second direction side of the armature
13. The method of claim 7, whereinchamber, whereby being able to pull the armature in thethe driver being a fluid driver;second direction when energized.
the actuation mechanism comprising an actuation cylinder,an actuation piston slideably disposed in the actuation