(12) United States Patent
`Tyler
`
`I IIIII IIIIIIII Ill lllll lllll lllll lllll lllll lllll lllll lllll 111111111111111111
`US006601821B2
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,601,821 B2
`Aug. 5, 2003
`
`(54) PROPORTIONAL CONTROL VALVE
`ASSEMBLY FOR EXHAUST GAS
`RECIRCULATION SYSTEM
`
`(75)
`
`Inventor: Jeffrey A. Tyler, Newark, NY (US)
`
`(73) Assignee: G. W. Lisk Company, Inc., Clifton
`Springs, NY (US)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by O days.
`
`(21) Appl. No.: 10/002,586
`
`(22) Filed:
`
`Nov. 15, 2001
`
`( 65)
`
`Prior Publication Data
`
`US 2002/0066441 Al Jun. 6, 2002
`
`Related U.S. Application Data
`(60) Provisional application No. 60/249,937, filed on Nov. 17,
`2000.
`Int. Cl.7 ................................................ F16K 31/12
`(51)
`(52) U.S. Cl. ....................................... 251/30.02; 91/387
`(58) Field of Search ........................... 251/30.01, 30.02;
`137/625.67; 91/387
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`3,757,823 A * 9/1973 Knutson ................ 137/625.64
`3,783,901 A * 1/1974 Schneider et al.
`..... 137/625.64
`
`4,201,116 A * 5/1980 Martin .................. 137/625.64
`4,485,846 A * 12/1984 Neff ........................ 251/30.01
`4,596,271 A * 6/1986 Brundage ................ 251/30.01
`5,366,202 A * 11/1994 Lunzman ................. 251/30.05
`5,520,217 A * 5/1996 Grawunde ............... 251/30.01
`5,605,289 A
`2/1997 Maley et al.
`............ 239/585.1
`5,632,258 A
`5/1997 Tsuzuki et al.
`............. 123/571
`5,865,156 A
`2/1999 Feucht et al. ............... 123/446
`6,024,060 A
`2/2000 Buehrle, II et al. .. ... . 123/90.12
`6,026,791 A
`2/2000 Arnold .................. 123/568.27
`6,050,248 A
`4/2000 Arulraja et al. ........ 123/568.11
`6,173,684 Bl
`1/2001 Buehrle, II et al. .. ... . 123/90.12
`6,178,956 Bl
`1/2001 Steinmann et al.
`123/568.21
`6,182,646 Bl
`2/2001 Silberstein et al.
`. ... 123/568.26
`
`* cited by examiner
`
`Primary Examiner---Ehud Gartenberg
`Assistant Examiner-John Bastianelli
`(74) Attorney, Agent, or Firm-Eugene Stephens &
`Associates; Thomas B. Ryan
`
`(57)
`
`ABSTRACT
`
`A two-stage proportional control valve assembly regulates
`flow of a first fluid such as an engine exhaust gas using a
`second fluid such as engine oil for power. A directional valve
`under control of an electrical actuator regulates flows of the
`second fluid to operate a fluid-powered actuator. A mechani(cid:173)
`cal connection between the fluid powered actuator and a
`flow control valve for regulating flows of the first fluid
`enables the electrical actuator to indirectly control the flow
`control valve with a minimum draw.
`
`22 Claims, 3 Drawing Sheets
`
`10 ' 34
`
`---
`
`120
`
`16\ I I
`,--_LJ I
`I
`_ _J
`I
`I
`I
`
`I
`I
`I
`I
`I
`__ _J
`
`t
`
`I
`I
`I
`I
`I
`L ____ _
`
`

`

`U.S. Patent
`US. Patent
`
`Aug. 5, 2003
`
`Sheet 1 of 3
`Sheet 1 0f 3
`
`US 6,601,821 B2
`US 6,601,821 132
`
`I__%nI
`Ind-Ur“.
`“@i
`
`an
`
`F I
`
`•
`(!)
`.......
`LL
`
`V
`.....
`
`“0——
`
`~,
`
`9
`
`r 91
`
`
`

`

`d •
`S:
`r:JJ.
`y)
`•
`~
`:9
`~ .....
`~ = .....
`
`8:
`
`a
`
`~
`
`e
`rJ'J.
`-..a-..
`a-..
`Q
`i,-
`O'J
`N
`i,-
`~
`N
`
`zaIzs‘109‘9sn
`
`120
`129
`
`---
`18
`Z
`------ I 76
`g
`---
`~ ({Q
`'I[:3
`fl‘
`%
`09
`‘—'-"'
`‘ / ‘V 26
`(2‘
`“L".
`124 §=I
`I."
`‘I‘Q‘§ 74 Eli? m
`~Ul
`‘. 122
`64
`g
`i“
`1‘
`’i’" \\: lfiiiVL€i§§X
`. _
`N
`V 7 38 /7}I4 1%“A\\ 72 :94”. All‘ yum-I)";1%};9"? u
`C
`
`
`8
`
`- /’/////”‘P‘
`l""““'~t‘=‘-‘-\\‘&—l -“
`
`/// ,6,1/71/11
`.
`.
`|.,....Wam
`
`
`'JJ. =(cid:173)~
`42
`1
`i /I6*5 Wi-We.”_’lf‘5—{€—:.é—E=w_—_§~‘\le.a
`g
`\-\\
`l
`L? l
`3“
`g
`V"\-‘\\\\\\\\\\\\
`130
`
`~ ....
`I so
`I "\Imun.._
`m\\\\
`{VII M “
`H
`‘F:fi.——_________
`
`N
`60 EB"1"mlll'
`u
`0 ....,
`t
`1
`I
`‘B-------------------------------
`16\ I
`I
`l
`t :
`t I I
`16\ I I
`I L
`24
`88
`r __ _LJ
`I
`L _______________
`__¢J|
`L_----------------,
`I
`_ _J
`_ _J
`I
`I
`I
`I
`I
`I
`I
`
`I
`I
`I
`_J
`
`10
`
`\
`
`10 '
`
`34
`
`-_
`
`‘
`
`12
`
`.
`
`FIG.2
` m'5 gN
`
`I
`
`1 |
`
`L____
`
`

`

`U.S. Patent
`US. Patent
`
`Aug. 5, 2003
`Aug. 5, 2003
`
`Sheet 3 of 3
`Sheet 3 of 3
`
`US 6,601,821 B2
`US 6,601,821 B2
`
`
`
`
`
`
`“A.‘‘Jul“Q"/m:—mm
`
`7ER?»5»?“Wm“PE,
`NHmm“ill“Kw$
`
`
`..E\_E
`
`onI
`
`
`
`
` NW€N\VN.NN\IHNIDNN1NI,NBIN--.'.
`
`mdm
`
`gm4%._.t«'m5.g-wr
`
`
`NNa:VA.‘
`,3w.I“
`§m¢fl_
`
`‘
`
`hmm
`
`
`
`

`

`US 6,601,821 B2
`
`1
`PROPORTIONAL CONTROL VALVE
`ASSEMBLY FOR EXHAUST GAS
`RECIRCULATION SYSTEM
`
`This application claims the benefit of U.S. Provisional
`Application No. 60/249,937, filed on Nov. 17, 2000, which
`provisional application is incorporated by reference herein.
`
`TECHNICAL FIELD
`
`A valve assembly regulates flow of a fluid or movement
`of a device by controlling the flow of a separate working
`fluid responsive to an electrical control signal.
`
`BACKGROUND
`
`Emission control systems for internal combustion engines
`recirculate a portion of the exhaust gases emitted from the
`engines back through the combustion process to lower
`harmful emissions. Exhaust gas recirculating valves
`(EGRV) connected to exhaust manifolds divert metered
`amounts of the exhaust gas to intake manifolds for re-burn
`by the engine. The exhaust gases are mixed with fresh
`air/fuel mixtures resulting in a lowering of combustion
`temperature and a reduction in the formation of harmful
`compounds such as nitrous oxide.
`
`SUMMARY OF INVENTION
`
`The invention features a two-stage proportional flow
`control valve assembly that is particularly useful for regu(cid:173)
`lating exhaust flow rates in exhaust gas re-circulating sys(cid:173)
`tems of internal combustion engines. Electrical control sig(cid:173)
`nals from an engine control module (ECM) regulate the
`exhaust flow rates through an exhaust valve utilizing engine
`oil pressure to produce a hydraulic actuating force. Since the 35
`electrical control signals are not required to provide the
`force for opening or closing the exhaust valve, my new
`two-stage proportional flow control valve assembly con(cid:173)
`serves electrical power for other functions.
`An exemplary two-stage proportional flow control valve
`assembly adapted for use as an exhaust gas recirculating
`valve incorporates an exhaust valve that regulates exhaust
`flow rates recirculated to an engine and a directional valve
`that utilizes engine oil pressure for regulating opening and
`closing of the exhaust valve proportional to control signals
`from an engine control module (ECM). Moveable compo(cid:173)
`nents of the exhaust valve are preferably pressure balanced
`with respect to the flow of exhaust gas through the exhaust
`valve to optimize positional accuracy. A fluid-powered
`actuator movable under the influence of engine oil pressure 50
`provides the necessary force for opening and closing the
`exhaust valve. The directional valve controls flow of the
`pressurized engine oil to the fluid-powered actuator to adjust
`the position of the exhaust valve proportional to the control
`signal.
`The movable portion of the exhaust valve is preferably a
`pressure-balanced dual poppet head body with each of two
`poppet heads having an approximately equal opposing area
`exposed to exhaust gas pressures. The dual poppet heads
`translate along a central axis for opening and closing exhaust
`passages encircled by mating poppet seats. The fluid(cid:173)
`powered actuator is preferably a double-acting cylinder
`having a piston mechanically coupled to the dual poppet
`head body for effecting common movement along the cen(cid:173)
`tral axis. The directional valve is preferably a four-way
`servovalve in the form of a spool valve that regulates flows
`of pressurized engine oil to opposite faces of the piston. The
`
`2
`spool valve includes a spool also movable along the central
`axis between (a) an initial position that charges a proximal
`face of the piston with the pressurized engine oil for moving
`the piston in a direction that closes the exhaust valve and (b)
`5 an actuated position that charges a distal face of the piston
`with the pressurized engine oil for moving the piston in a
`direction that opens the exhaust valve.
`An electrical actuator preferably in the form of a propor(cid:173)
`tional solenoid under control of the electronic control mod-
`10 ule (ECM) converts the control signals of varying current
`into proportional forces imparted by an armature against the
`spool along the central axis. A feedback mechanism, pref(cid:173)
`erably in the form of a compression spring, also located
`along the central axis, applies a separating force between the
`spool and the piston proportional to its displacement. An
`15 adjustable null compression spring or other biasing mecha(cid:173)
`nism biases the solenoid armature against the spool. Thus,
`the spool and the armature are preferably biased together
`from opposite directions by two springs-the null spring
`acting on the spool in the same direction as the solenoid
`20 armature and the feedback spring acting on the spool in the
`opposite direction.
`In the absence of an actuating force from the solenoid, the
`feedback spring, which is the stronger of the two springs,
`biases the spool against an armature stop, which corresponds
`25 to the initial spool position at which the proximal face of the
`piston is pressurized for closing the exhaust valve. Com(cid:173)
`pression of the null spring can be adjusted to establish a
`proper take-off current to the solenoid at which the sum of
`the forces imparted by the null spring and the solenoid are
`30 sufficient to move the spool against the feedback spring.
`Additional current moves the spool further against the
`feedback spring to the actuated position at which the distal
`face of the piston is pressurized for opening the exhaust
`valve.
`Upon reaching the actuated position, further movement of
`the spool is limited by contact between the solenoid arma(cid:173)
`ture and the armature stop. The initial and actuated positions
`can be adjusted to set maximum flow rates through the spool
`valve in either direction. Movement of the spool to the
`40 actuated position compresses the feedback spring up to the
`limit set by the armature stop. Movement of the piston in
`response to the charging of its distal face further compresses
`the compression spring until a counteracting force exerted
`by the piston through the compression spring momentarily
`45 exceeds the sum of the forces exerted on the spool by the
`null spring and solenoid and returns the spool to a so-called
`neutral position (i.e., a position between the actuated and the
`initial positions) at which further flow to the piston is
`stopped.
`Actuating forces exerted by the solenoid above the take-
`off current temporarily move the spool beyond the neutral
`position until the counteracting force of the piston returns
`the spool to the neutral position. Although the spool returns
`to the same neutral position throughout the intended range of
`55 solenoid actuating forces above the take-off current, the
`piston's position ( and with it the position of the dual poppet
`head body of the exhaust-valve) varies directly with the
`compression of the feedback spring. Any change in the
`actuating force produces a corresponding change in the
`60 compression of the feedback spring, which exerts a force
`equal and opposite to the sum of the forces exerted on the
`spool by the null spring and the solenoid. The force exerted
`by the null spring remains the same at the neutral position,
`so the change in the force exerted by the feedback spring
`65 matches the change in the force exerted by the solenoid.
`The feedback spring is the sole mechanical connection
`between the piston and the spool. The amount that the
`
`

`

`US 6,601,821 B2
`
`3
`feedback spring is compressed is controlled by the amount
`of current that is applied to the solenoid. Movement of the
`spool to the actuated position starts the compression of the
`feedback spring, and the engine-oil powered displacement
`of the piston completes the required compression of the 5
`feedback spring while restoring the spool to the neutral
`position. The amount of compression of the feedback spring
`determines the spacing of the piston from the spool in the
`neutral position. Changes in the position of the piston are
`accompanied by corresponding changes in the position of 10
`the dual poppet head body of the exhaust valve.
`The control signal (i.e., current) to the solenoid provides
`a proportional control that modulates both opening and
`closing of the exhaust valve, while the force for actually
`operating the exhaust valve is derived from engine oil
`pressure. Neither changes in the engine oil pressure nor
`changes in the external pressure applied to the dual poppet
`head body unduly affect the exhaust valve position. The
`spool valve maintains the position of the piston indepen(cid:173)
`dently of overall oil pressure, which can affect flow rates but 20
`not ultimate positions of the valve components. The neutral
`position blocks flows to or from either side of the piston to
`maintain the exhaust valve in a desired position. Balancing
`the dual poppet head body to exhaust gas pressures also
`limits the influence of the exhaust gas pressures or flow rates 25
`on the valve position. This independence of the new two(cid:173)
`stage proportional control valve from changes in the exhaust
`and engine oil pressures, together with the linear and pro(cid:173)
`portional modulation of flow rates through the exhaust valve
`with respect to the electrical control signal, makes this new 30
`valve particularly accurate, reliable, and robust.
`The new valve is expected to contribute to reducing
`harmful engine emissions while operating more efficiently
`by utilizing engine oil pressure to move the exhaust valve.
`The valve is also expected to have a variety of other uses in
`situations where proportional movement of a valve or other
`device is modulated by low-power control signals regulating
`the flow of working fluid in an intermediate actuator.
`
`4
`Flows between the exhaust gas inlet passages 30 and 32
`and the combined exhaust gas outlet passage 34 are inter(cid:173)
`rupted by a dual poppet head body 36 that is movable along
`a central axis 38. The dual-poppet head body 36, includes (a)
`a first poppet head 40 that mates with a seat 42 encircling an
`end of the inlet passage 30 for restricting flows between the
`inlet passage 30 and the combined outlet passage 34 and (b)
`a second poppet head 44 that mates with a seat 46 encircling
`an end of the inlet passage 32 for restricting flows between
`the inlet passage 32 and the combined outlet passage 34. The
`two poppet head seats 42 and 46 have equally sized pressure
`areas, and the inlet passages 30 and 32 apply exhaust gas
`pressure to the two poppet heads 40 and 44 from opposite
`directions to balance the dual poppet head body 36 with
`15 respect to the exhaust gas pressure. The dual poppet head
`body 36 also includes a shank 48 mounted within a guide
`bore 50 of a housing flange 52. The shank 48 communicates
`motion along the central axis 38 for opening and closing the
`exhaust valve 20.
`The double-acting cylinder 24, which functions as a
`hydraulic actuator, includes a piston 60 having a head 62 that
`divides a housing bore 64 into two separately pressurizable
`chambers 66 and 68 (shown in FIG. 3). A shank 70 con(cid:173)
`nected to the piston head 62 is coupled directly to the shank
`48 of the dual poppet head body 36. A guide bore 72 formed
`within a housing flange 74 supports movement of the entire
`piston 60 along the central axis 38.
`The four-way servovalve 22 is a spool valve having a
`supply port 76 connected to source of engine oil pressure
`(not shown) and a tank port 78 connected to an engine oil
`sump (also not shown). Within the housing 12, a spool guide
`tube 80 supports a spool 82 for movement along the central
`axis 38. The supply port 76 feeds pressurized oil through the
`housing 12 to a supply passage 84 in the guide tube 80. Oil
`35 collected in a return passage 86 in the guide tube 80 returns
`through the housing 12 to the tank port 78. A working
`passage 88 also formed in the guide tube 80 and the housing
`12 directs flows of the engine oil to or from the cylinder
`chamber 66. An axial bore 90 within the spool 82 commu-
`40 nicates openly with the cylinder chamber 68.
`On its peripheral surface, the spool 82 has a pair of
`annular lands 92 and 94 that open and close alternative flow
`paths between the supply passage 84 and the return passage
`45 86. Both the supply passage 84 and the return passage 86 are
`alternately connectable to the working passage 88 and the
`axial bore 90 for charging and discharging the cylinder
`chambers 66 and 68 on opposite sides of the piston head 62.
`An annular recess 96 formed in the circumference of the
`50 spool 82 between the spool lands 92 and 94 alternately
`connects the working passage 88 to either the supply pas(cid:173)
`sage 84 or the return passage 86. Radial bores 100 and 102
`formed through the spool 82 straddling the two annular
`lands 92 and 94 alternately connect the axial bore 90 to
`55 either the supply passage 84 or the return passage 86. The
`spool 82 is balanced with respect to the engine oil pressure.
`The feedback compression spring 26 extends between the
`piston head 62 and the spool 82. One end of the compression
`spring 26 is mounted within a recess 108 in a proximal face
`60 110 of the piston head 62, and the other end of the spring 26
`is mounted in an open end face 112 of the spool 82. The
`feedback spring 26 exerts a reactionary force inversely
`proportional to the amount of separation between the piston
`head 62 and the spool 82.
`A solenoid 116, which functions as an electrical force
`motor actuator, pushes the spool 82 against the feedback
`compression spring 26 through a limited range of travel. A
`
`DRAWINGS
`
`FIG. 1 is a plan view of an exemplary exhaust gas
`re-circulation (EGR) valve in accordance with my invention.
`FIG. 2 is a side cross-sectional view through the valve.
`FIG. 3 is an enlarged cut away of the view in FIG. 2
`showing a spool valve portion in clearer detail.
`
`DETAILED DESCRIPTION
`
`The exhaust gas re-circulating valve of the three drawing
`figures is a two-stage proportional control valve assembly 10
`having a housing 12 that can be bolted or otherwise attached
`(e.g., through bolt holes 14) to an internal combustion
`engine exhaust manifold 16 shown by phantom line in FIG.
`2. Within the housing 12 are assembled an exhaust valve 20
`and a four-way servovalve 22 interconnected in succession
`by a double-acting cylinder 24 and a feedback compression
`spring 26.Aheat shield 18 protects the servovalve 22 and the
`double-acting cylinder 24 from exposure to heat from the
`exhaust manifold 16.
`The exhaust valve 20 regulates flows between two
`exhaust gas inlet passages 30 and 32 and a combined exhaust
`gas outlet passage 34 formed within the housing 12. The two
`exhaust gas inlet passages 30 and 32 admit exhaust gases
`from the engine exhaust manifold 16. The exhaust gas outlet 65
`passage 34 directs a metered flow of the exhaust gases
`toward an engine inlet manifold (not shown).
`
`

`

`US 6,601,821 B2
`
`5
`coil 118 powered by a range of electrical currents regulated
`by an electronic control module (ECM) 120 generates a
`magnetic force on an armature 122, which is moveable along
`the central axis 38 within a solenoid guide bore 124. An
`actuator rod 126 passing through an armature stop 128 5
`connects the armature 122 to the spool 82. A null compres(cid:173)
`sion spring 130 biases the armature 122 and the actuator rod
`126 against one end of the spool 82 with an initial force that
`is slightly less than the initial force exerted on the other end
`of spool 82 by the feedback spring 26.
`When no current is applied to the solenoid 116, the
`stronger feedback spring 26 biases the spool 82 to an initial
`position shown in FIGS. 2 and 3. The spool 82 is forced back
`against the armature stop 128 to the initial position that
`partially opens a passageway through the radial bore 100
`between the supply passage 84 and the axial bore 90 for
`charging the cylinder chamber 68. At the same initial
`position, a passageway through the annular recess 96 pro(cid:173)
`vides an opening between the working passage 88 and the
`return passage 86 for discharging the cylinder chamber 66. 20
`The pressure in cylinder chamber 68 produces a hydraulic
`force against the proximal face 110 of the piston head 62 and
`pushes the piston 60 in a direction that maintains the exhaust
`valve 20 in a closed position.
`Applying current to the solenoid 116 above a given 25
`take-off current moves the spool 82 away from the armature
`stop 128 and further compresses the feedback spring 26. The
`further movement of the spool is limited by contact between
`the solenoid armature 122 and the armature stop 128 at an
`actuated position that discharges the cylinder chamber 68 30
`and charges the cylinder chamber 66. At the actuated
`position, the annular recess 96 connects the supply passage
`84 to the working passage 88 for charging the cylinder
`chamber 66, and the radial bore 102 connects the axial bore
`90 to the return passage 86 for discharging the cylinder 35
`chamber 68.
`The accumulating pressure in the cylinder chamber 66
`produces a hydraulic force against a distal face 134 of the
`piston head 62 that moves the piston head 62 together with
`the dual poppet head body 36 in a direction that compresses
`the feedback spring 26 and opens the exhaust valve 20. The
`movement of the piston head 62 further compresses the
`feedback spring by an amount required to momentarily
`overcome the combined forces of the solenoid 116 and the
`null spring 130 and return the spool 82 to a neutral position
`at which further flows to and from the double-acting cylin(cid:173)
`der 24 are blocked.
`At the neutral position of the spool 82, which is located
`between the initial and actuated positions, the spool 82 locks
`fluid in the cylinder chambers 66 and 68, thus locking the
`position of the double-acting cylinder 24 and the exhaust
`valve 20. The feedback spring 26 is compressed by an
`amount that exerts a force against one end of the spool 82
`equal and opposite to the combined forces exerted by the
`solenoid 116 and the null spring 130 against the opposite end
`of the spool 82. Any movement of the piston head 68 that
`would change the compression the feedback spring 26
`reverses flow through the double-acting cylinder 24 and
`restores the piston head 26 to the position required to
`maintain the spool 82 in the neutral position.
`The minimum actuating force of the solenoid 116 (i.e., the
`takeoff current) required for opening the exhaust valve 20
`compresses the feedback spring 26 by an amount that moves
`the spool 82 just beyond the neutral position. The counter(cid:173)
`acting hydraulic force generated by the double-acting cyl(cid:173)
`inder 24 moves the piston head 62 and with it the dual
`
`6
`poppet head body 36 by an amount required to return the
`spool 82 to the neutral position. The exhaust valve 20 opens
`by the amount the feedback spring 26 is compressed by the
`movement of the spool 82 beyond the neutral position.
`Applying more current to the solenoid 116 momentarily
`moves the spool 82 to the full activated position at which
`further movement of the spool is stopped by contact between
`the solenoid armature 122 and the armature stop 128.
`Differential pressure across the piston head 62 builds until a
`10 hydraulic force against the distal face 134 of the piston
`acting through the feedback spring 26 forces the spool 82 to
`return to the neutral position. Initially, the feedback spring
`26 is compressed by movement of the spool 82 toward the
`piston head 62 until the spool 82 reaches the actuated
`15 position. In response, the piston head 62 moves toward the
`travel-limited spool 82, additionally compressing the feed(cid:173)
`back spring by an amount required to overcome the remain(cid:173)
`ing combined forces of the solenoid 116 and the null spring
`130 and thereby return the spool 82 to the neutral position.
`The change in position of the piston head 62 along with
`the dual poppet head body 36 can be far beyond the limited
`range of spool travel and is substantially proportional to the
`change in the solenoid actuating force. The travel range of
`the spool 82 is limited to control maximum flow rates to and
`from the double-acting cylinder 24 as a compromise
`between response time and valve stability. The travel range
`of the piston head 62 of the double-acting cylinder 24
`corresponds to the desired range of travel of the dual poppet
`head body 36 of the exhaust valve 20. The spring rate of the
`feedback spring 26 is set so that the change in compression
`of the feedback spring 26 in response to the range of
`actuating forces imparted by the solenoid 116 matches the
`desired range of travel of the dual poppet head body 36.
`Applying less current to the solenoid 116 momentarily
`moves the spool 82 toward the initial position, where the
`spool remains until movement of the piston head 62 in the
`opposite direction decompresses the compression spring 26
`equal to the reduced solenoid actuating force. Differential
`40 pressure across the piston head 62 is reduced or, if necessary,
`momentarily reversed to restore the spool 82 to the neutral
`position. A new equilibrium is restored at the neutral posi(cid:173)
`tion of the spool 82 with the feedback spring 26 less
`compressed and with the dual poppet head body 36 in a less
`45 open position of the exhaust valve 20.
`The maximum actuating force of the solenoid 116 is only
`required to withstand the maximum compression of the
`feedback spring 26, whose spring rate can be specifically
`tailored to the force range of the solenoid 116. The hydraulic
`50 force produced by the double-acting cylinder 24 provides
`whatever force is actually necessary to move the dual poppet
`head body 36 and to counteract the forces imparted by the
`solenoid 116. Thus, engine oil pressure provides the primary
`force for opening and closing the exhaust valve 20, while
`55 electrical current is required mainly for purposes of control
`(i.e., choosing the desired position of the exhaust valve). In
`fact, the actuating force imparted by the solenoid 116 for
`opening the exhaust valve 20 points in a direction opposite
`to the direction the double-acting cylinder 24 moves the dual
`60 poppet head body 36 for opening the exhaust valve 20.
`Although specific examples have been given of flow
`control valves or devices, directional valves, biasing
`mechanisms, and fluid-powered and electrical actuators for
`use in my new two-stage proportional flow control valve
`65 assembly, other such valves, devices, mechanisms, and
`actuators can be substituted in accordance with the overall
`teaching of this invention for regulating not only flows of
`
`

`

`US 6,601,821 B2
`
`7
`exhaust but other fluid flows or mechanical movements that
`are independent of the source of fluid pressure for operating
`the valve assembly. For example, the exhaust valve can be
`a flow control valve having the same or different seating
`action for regulating flow rates. The source of fluid pressure 5
`for operating my new valve is preferably different from both
`the fluid flows regulated by the valve and the control signals
`imparted to the valve. Instead of opening and closing a flow
`control valve, the proportional control can be arranged to
`adjust the operating positions of other hydraulic or mechani- 10
`cal devices as a function of a low-power control signal.
`I claim:
`1. A two-stage proportional control valve assembly com-
`prising:
`a flow-regulating valve that regulates a flow of a first 15
`fluid;
`a double-acting actuator powered by a second fluid for
`moving the flow-regulating valve in different open and
`closed directions for correspondingly opening and clos(cid:173)
`ing the flow-regulating valve;
`a directional valve that controls a flow of the second fluid
`to the double-acting actuator;
`an electrical actuator that converts a control signal into a
`force acting on the directional valve for adjusting a 25
`position of the double-acting actuator in accordance
`with the control signal;
`the double-acting actuator having
`(a) a first surface arranged for exposure to fluid pres(cid:173)
`sure of the second fluid for moving the flow-
`regulating valve in the open direction and
`(b) a second surface arranged for exposure to fluid
`pressure of the second fluid for moving the flow(cid:173)
`regulating valve in the closed direction; and
`the directional valve being movable under influence of the 35
`electrical actuator between
`(a) a first position that directs a flow of the second fluid
`to the first surface of the double-acting actuator and
`(b) a second position that directs a flow of the second
`fluid to the second surface of the double-acting 40
`actuator.
`2. The valve of claim 1 in which the directional valve is
`a four-way directional valve that regulates flows of fluid to
`and from the first and second faces of the double-acting
`actuator.
`3. The valve of claim 2 in which the double-acting
`actuator is a double-acting piston, and the first and second
`surfaces of the double-acting actuator are opposing surfaces
`of a piston.
`4. The valve of claim 2 in which the directional valve is 50
`a spool movable between
`(a) the first directional valve position, which
`(i) provides communication between the first surface of
`the double-acting actuator and a supply port that is
`connectable to a high-pressure side of a fluid power 55
`source and
`(ii) provides communication between the second sur(cid:173)
`face of the double-acting actuator and a tank port that
`is connectable to a low-pressure side of the fluid
`power source, and
`(b) the second directional valve position, which
`(i) provides communication between the second sur(cid:173)
`face of the double-acting actuator and the supply port
`that is connectable to the high-pressure side of the
`fluid power source and
`(ii) provides communication between the first surface
`of the double-acting actuator and the tank port that is
`
`8
`connectable to the low-pressure side of the fluid
`power source.
`5. The valve of claim 4 in which the spool is also
`moveable to a neutral position at which communication
`between both the first and second surfaces and the supply
`and tank ports is blocked.
`6. The valve of claim 5 in which a feedback spring
`connects the spool to the double-acting actuator, and move(cid:173)
`ment of the spool to the first directional valve position also
`moves the double-acting actuator in a direction that com(cid:173)
`presses the feedback spring and moves the flow-regulating
`valve in the open direction.
`7. The valve of claim 6 in which movement of the spool
`to the second directional valve position also moves the
`double-acting actuator in a direction that decompresses the
`feedback spring and moves the flow-regulating valve in the
`closed direction.
`8. The valve of claim 5 in which a feedback spring
`connects the spool to the double-acting actuator, and move-
`20 ment of the spool to one of the first and second directional
`valve positions also moves the double-acting actuator in a
`direction that restores the spool to the neutral position.
`9. The valve of claim 8 in which movement of the
`double-acting actuator adjusts compression of the feedback
`spring in relation to the force imparted by the electrical
`actuator on the directional valve.
`10. The valve of claim 9 in which the double-acting
`actuator is mechanically connected to the flow-regulating
`valve and a range of open positions occupied by the flow(cid:173)
`regulating valve correspond to different compressions of the
`feedback spring.
`11. The valve of claim 1 in which the flow-regulating
`valve includes a poppet head pressure balanced with respect
`to the first fluid and freely movable with the double-acting
`actuator.
`12. A method of controlling flow rates of a first fluid
`utilizing fluid pressure supplied by a second fluid compris(cid:173)
`ing the steps of:
`converting an electrical signal into a force imparted to a
`directional valve that controls a flow of the second fluid
`to a double-acting actuator;
`moving the directional valve in response to the force
`converted from the electrical signal between a first
`position that directs a flow of the second fluid to a first
`surface of the double-acting actuator and a second
`position that directs a flow of the second fluid to a
`second surface of the double-acting actuator;
`providing feedback between the double-acting actuator
`and the directional valve that overcomes the force
`imparted to the directional valve and restores the direc(cid:173)
`tional valve to a neutral pos