Note: Descriptions are shown in the official language in which they were submitted.
L631~ ~ l
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BACK(~7ROUND AND SUL~IARY OF THE PRESENT INVENTIo~
The presen~ invention relates to a Elow control
mechanism for providing a variable fluid flow ana, in
particular, relates t~ a mechanism which operates to
control flow in response to a~ electrical signal~ -
Obviouslyl ~luid flow from a pump can be contr~lle~
by a variable orifice, and a valve which main~ain~ a
constant pressure dro~ across the orifice~
In some applications the valve ~or maintaining the
constant pressure drop across the orifice can be a bypass
valve. Commonly a bypass valve ports fluid from the pump
outlet directl~ to the pump inlet. Whe~ the ori~ice area
is varie~, the change in pressure drop across the ori~Lce
is sensed and the b~pa5s valve moves to b~pass more or
less ~luid to thereb~ maintain the constant pressur~ ~rop
,. ,. . - ,,
across the orifice.
C~man, U.S. patent 4,099,893 also as~igned to TRW
Inc. discloses a flow contr~l mecha~ism as reEerrea to
above. It includes a pintle member and a ~alve seat which
to~ether define a variable ~rifice. The pressu~e arop
across the ori~ice controls a bypass valve. The pintle
member is positioned by an electrically actua~ed rack and
pinion gear arrangement. Obviously, the position of the
pintle member depen~s upon ~he time interval during which
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.
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~he motor is energized, the inertia of the motor and ~r
arrangement, etc. Thus acc~ate c~ntrol of fluid flo~ is
delayed because o the amount of time required to position
the pintle mem~er. ~lso, it is difficult to accurately
position the pintle. This iS due to the pintle position
being dependent up~n the time interYal of operation o~ the
motor, whic~ time interval îs cumbersome to control.
Furthermore, the position of the pintle mem~er may not be
known when an aajustment is initiated, since the pin~le
member does not inherently return t~ a predetermined
position either upon start-up or shutdown.
The flow control mechanism of the present invention
is particularly use~ul for regulating the flow from a
constant displacement pump, such as a ~ear pump~ The flow
control mechanism may be constructed together with t~e
pump in a single integral unit or may ~e a separate unit.
Basically, the flow control mechanism comprises a variable
orifice and a bypass valve which is operated by a pressure
- differential across the variable orifice. The bypass
valve allows a pintle Yalve to malntain a cons~ant ~
pressure dr~p across an ori~ice in the outlet of the pump
and thus a desired cons~ant flow to the system~ If the
orifice size is changed, the rate of flow to the system is
changed.
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The present invention provides an apparatus for controll-
ing fluid flow comprising a housing, a variable orifice located in
said housing, a valve adjacent to said variable orifice and
directly responsive to the pressure drop across said orifice and
maintaining the pressure drop across said orifice substantially
constant as the size of said orifice is varied and if the pressure
downstream of said orifice varies, said variable orifice being
defined by a surface of a valve seat and a first surface of a
pintle valve member, said pintle valve member being movable relative
to said valve seat between. differen~ open positions in which said
first surface of said pintle.valve member is spaced from said valve
seat to thereby vary the size of said orifice, means in said
housing for supporting said pintle valve member for movement
relative to said housing, said pintle valve member having a second
surface which is oppositely directed and axially spaced from said
first surface, said pintle valve member being positioned by fluid
pressure acting on said first and second surfaces, means for apply-
ing a fluid pressure to said second surface of said pintle valve
member, a fluid passage communicatin~ the fluid pressure acting on
said second surface with the fluid pressure acting on at least a
portion of said first surface, means for varying the fluid pressure
- acting on said second surface of.said pintle valve member to cause
said pintle valve member to move between open positions with respect
to said valve seat, said means comprising a pilot member movable
relative to said fluid passage and restri~ti~g flow through said
passage to a degree depending upon the position thereof, and an
electrical solenoid for moving said pilot member relative to said
fluid passage to vary the fluid pressure acting on said second
surface of said pintle valve member, whereby variation of the
--4--
~ ~3:~5
amplitude of said electrical signal results in a corresponding
variation in the fluid flow through said variable orifice. Since
the magnitude of the electrical signal will depend upon the
amplitude of the electrical signal which controls the solenoid,
the position of the pilot member with respect to the discharge
passage will be directly dependent upon the amplitude of this
electrical signal.
The means for applying the aforementioned fluid pressure
to said second surface of said pintle valve is provided by a
pressure chamber adjacent the second end of the pintle which is
supplied with fluid. The pressure in the chamber acts against the
area of the second end of the pi~tle to create a force opposing the
force acting against the first end of the pintle. A fluid dis-
charge passage allows fluid to flow from the pressure chamber.
The present invention is an improvement in the structure
disclosed in United States Patent 4,099,893. The pintle member in
the present invention is positioned immediately upon the solenoid
being energized. Thus, positioning of the pintle is not time
dependent, as when the pintle is moved by a motor as in 4,099,893.
Further, in the present invention, the pintle returns to a pre-
determined position when the solenoid is deenergized. Accordingly,
the position of the pintle is known when adjustment is initiated by
energization of the solenoid.
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~ 1 ~.63165 ~ ~
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:
IBRIEF D~SCR:i.PT:~ON OF THE D~A~INt'5
The foregoing and other objects ~nd advantages Q~ the
present invention will become more reaaily apparent ~rom
the following description of preferred embodiments o~ ~he
invention, taken in conjunction with the accompanyin~
drawings wherein: .
Fi~. 1 is an elevational view, p~r~ly in section, o
a unit embo~ying ~he present inven~ion;
Fig. 2 is a sectional view,ta~en approximatel~ along
lines 2-2 of ~ig. 1;
Fi~. 3 is a sectional view of a bypass valve
structure,which is incorporated in the pump unit of Fig. l;
Fig. 4 is a sectional view of the flow oontrol ' ~ .
solenoid of Fi~, l; ' - , .
~ ig. S is a sectional view of a second embodimen~ of
~ ..
the present invention;
, Fi~. ~ is a sectional view of still another : . .
embodiment of the present invention, and
' Fig, 7 is a sec~ional view of s~ill a ~urt~er .
: embo~imen~ o~ the present invention. . ~-
. _ESCRIP~IO~ OF T~IE PREFERRED EMBOD~ENT
' , Fi~s. 1 ana 2 show a variable flow pump assembl~ A. --
,The assembly A incl~des a cons~nt displaoement pump B and
-~ a 10w control mechanism associated with the pump B. The
flow control mechanism includes a bypass valve struct~rc C . .
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3 ~ 6 5
-7
and a pilot controlled ~echanism D. The byp~s~ val~
structure C and the pilot controlled mechanism D coopera~
to control flow to ~he ~luid system suppl;ed b~ th~ pu,~p B,
~ he pilo~ controlled mechanism D includes a v~riable
orifice F. Flow Erom the pump B is c~ntrolled by varying
the size o the orifice ~`- The b~pass valve structure C
regulates the pressure drop across variable oriEice ~ by -
shun~ing controlled amounts o~ fluid from ~he pump outlet
bact~ to the pump inlet. .
As shown in ~igure 2~ the constant displacement pump
B includes a housing 11 which defines a pumpin~ chamber
12. A gear pump mechanism is located in pumping chamber .
12 and comprises a pair of gear members 13, 14~ The gear
member 13 is drivingly connected t~ an input shaft 15
which is supported by suitable bearings 16, 17 located in .
the housing ll.- The gear member 14 meshe5 with the ~ear .
member 13 and is likewise supported in suitable bearin~s
18, 19 for rotation ~elative to the hDusing 11. The
specific structure of the gear pump ana bearings an~ seals
may take a variety of differen~ forms, and will not be
described in de~ail since these elements are not importan~
tc) the presen~ inventionO
The pumping chamber 12 communicates with a p~mp inlet
3~ by passages which are no~ shown. As the gear members
13, ~4 Fotate at a constant velocity, ~luid is drawn from
.
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--8--
the inlet 30 and is pumped at a constant Elow rate to the
bypass valve C through a transver~e passage 32. The
passage 32 communicates with a pump outlet chamber 33.
The fluid flows from outlet chamber 33 through the
variable orifice F to the system supplied by the pump.
The bypass valve structure C bypasses fluid from pump
outlet chamber 33 to the pump inlet 30.
~ he variable orifice F is defined by a bore 34 of a
valve seat 35 which is threadedly received in the housing
11 and by the tapered nose 37 of a pintle member 36.
Pintle member 36 has a generally circular cross-section,
and is slidably received within a sleeve 51. The orifice
F is varied in size by movement of the pintle member 36
relative to the valve seat 35. Pintle member 36 is freely
movable relative to valve seat 35, i.e. is unrestrained by
a spring bias or the like~ By varying the si~e of the
orifice F, the amount of fluid flow from the pump outlet
chamber 33 to outlet chamber 31 is varied. The outlet
chamber 31, of course, is connected with the fluid system
supplied by the pump.
The shape oE the tapered nose 37 of pintle 36 will, in
a preferred embodiment, be of a generally paraboloid
configuration. When configured in this manner, the flow
area of orifice F will be substantially linearly related
to the positon of pintle 36. The shape of nose 37 may,
I lB3165 ~ ~
g I
however, alternatively be ~elected to he other-
configurations i~ different functional relationships
between the position o pintle 36 and the resl~lting f10-
~area of o~ifice ~ are desired.
The pintle 36 is moved by fluid pressures actLng
thereon. The right end o~ the pintle member 36 r as vî~w~
in the drawings, is acted on by difEerent pressures. ~-lore
specifically, due to the tapered ~hape o~ nose 37~
different sections of the nose will be locatea di~erent
distances from the valve seat 35. Beca~se o ~his, the
fluid pressure acting upon nose.37 will no~ be const~nt
over the entire surface of the nose. The tip of the nose
37 will be exposed to the greater pressure in the pump
~u~let chamber 33, with other sections experiencing lesser
pressuresO The.opposite.end ~3 of the pintle member 36 iS
acted upon by fluid pressure in a control chamber 4~. -
Infinite positioning of pintle member 36 is effec~e~
by infinitely varying.the fluia pressure in the con~rol
chamber 42. When the fluid pressure in control chamber 42
is changed, pintl~ member 36 will be forced~ by the
resulting differential in the forces acting across it, to
a new position wherein the forces acting on the opposite
ends thereof are a~ain equ~l, The pressure in chamber 42
is controllea by means of a pilot member 40 which opera~es
in conjunction with a passage 41. The passage 41 is
through the plntle ember 36 itself.
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1631
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The pa~sa~e 4L in pintle Inember 36 pro~ide~ ~luid
flo~ commun;cation ~rom chamber 42 to outlet 31. ~luid i5
sllppli ed f rom chamber 33 to chamber 42 b~ means of a .
pa~ssage 44 in the housin~. The passaye 4~ is partially
indicated by the dotted line 46. The passage 44 has a
flo~ restriction 4~ therein. The flow area of the
restriction 4~ is selected to be smaller than the
unrestricted flow area of fluid discharge passage 41 in
the pintle ~ember 36. In a preferred embodiment, passa9e
44 is drilled into housing 11 parallel to pintle member
36, and behind it ~as seen in Fig. 1)~ ~or convenience o~
description, this passage is instead shown rotated 9~ out
of position so that it lies within the plane o~ the -
section of Fig~ 1.
When the pintle 36 is in a given steaay sta~e
: -;
p~sitlon~ the pressure ~rop from chamber 33 to chamber 31
across the variable ori~ice F equals the sum o~ the
prçssure drops across the restriction 45 ana pintle 36.
Thus, the pressure in~chamber 42 is slightly higher than
the pressure in chamber 31. The pintle îs balanced by the
,
fluid ~orces actin~ thereon because~ as n~ted above, the
tip of the nose 37 of the pintle projects c~ose to the
valve seat 3~ and has a higher pressure actin~ thereon ~
than the pressure down stream thereof. Thus, the pressure
gradient acting on the xight èna of the pintle 36 provides
,
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... .. ~.. . . ...... _.. ~.. ..... .. . ..... _ .
.
- ~ 1 1631~ ~ ~
a tot~:l force acti.n~ on the right end of the pin~le ~ ic~
is bal~3ncecl by the Eorce act.ing on the lef~ end of ~le
pintle in a steady state con~ition~
~ ovement of the pin~le member 36 is effected by
movement of the pilot member 40. When the pilot member ~:0 -
moves to~ard the pintle member 36, flui~ fl3w ~hro~h
passage 41 is restricted. Pressure in chamber 42
increases and the p;ntle member 36 moves toward ~he riqht
in Fig. 1 to restrict flow throug~ orifice F~ ~lovemen~ o~
the pil ot 40 toward the le~t relative to the pintle 36
results in the pressure in charnber 42 decreasing due to
the fact that passage 41 direc~s more ~luid therefrom.
The pin~le 36, of course, moves to the left or to the
ri~ht un~il the fluid pressures acting thereon are
balanced.
From the above, it should be apparent that the pilot .
member 40 need not be capable vf ac~ing against the ful~ -
fl~id force applied to the tapered nose 37 of the pintle
Thus, the pintle member 36 is positioned, not by a air~ct .
force appliea to it by t~e pilot member 4~ bu~ rather ~y
the change in pressure in control chamber 4~ which results
from a change in position of pilot member 4Q. Pilot
member 40 will generally be pressure balanced so that only
a relatively small force is required to reposition it.
Control elements ma~ therefore be em~loyea to control the
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3 1 ~ 5 ~ ;~
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pilot member, and thus flui~ ~low, whose use ~o~lld ha.
been imposs;ble witho~t t~is force arnplification ~eatt2re.
The pilot member 40 can, for ex~mple, be positioned ~y a
small solenoid or by ot~1er mode~e sized control elemen~s.
In Figure l, a solenoid 47 is included for
positioning pilot member 4~ relative to pin~le member 36
The position o the pilot member 40 is directly related ~o
the ma~ni~ude of the electrical current which is supplied
to the solenoid 47. If solenoid 47 is fully eneryized,
then the pilot member 40 will be pul~ed into a fully
retracted posi'c.ion (lef tward, as viewed in :Fig_ 1) . In
this event, the pilot member 40 wil- provide little
restriction of the fIow of fl~id rom chamber ~2 into
chamber 31 via passage 41. Consequentlyr fluid will flow
from chamber 33 through passage 44 and flow restriction 45
.
into chamber 42. From chamber 42, the fluia will flow
through ~lui~ disch~rye passage 41 in pintle member 36 ana
thus into the outlet.por~ ~1. Because flow throwgh
passage 41 i5 now unrestricted by pilot member 40, the
pressure in chamber 42 will decrease. A force
differential will therefore exist across pintle member 36 .
which will cause it to move to a le~tward posîtion so tha~
orifice ~ will be fully open. Ori~ice ~ is shown in this
full~ open position in F~.~l.
As the ~mount of current whi~h is supplied to
solenoid 47 is decreased, pil~t valve. 4n will emerge from
~163:1~5
solenoi~ 47 (move to the r ic~ht as viewed in ~ig. 1) .~r~d
~ill r~st~ict ~he flow of ~luid from chamber 42 into
chamber 31 by increasin~ amounts. At a given positiO
pilot valve 90, a given pressure will be buil~ up wi~hin
chamber 42 due to the flow restriction provided by the
pilot valve. Thus, -as the pressure within chamber 42
incre~ses, a ~orce differential will ~uild up across
pin~le member 36 which will cause it ~o mov~ ~oward the
valve seat 35. ~s the tapered nose approaches and enters
the valve seat, however~ it will be subject to increasing
fluid pressure due to the higher pressure levels within
chamber 33 and ~he valve seat 35. The pintle member 36
will therefore come to xest at a new position where the
forces on opposite ends thereof are e~alized.
Likewise, if the pintle 36 is in a steady state
,: , .
condition and the pilot member 40 is moved a small
distance to the let, the pressur~ in chamber 42 will be
reduced. The pintle 36 will then move to the left and
follow the pilot member 40.
This will result in a positioning of pintle member 36
which is depenaent upon the pressure build up in chamber
42. ~his, in turn, is dependen~ upon ~he position of
pilot member 40. Consequently, by in~initely varying ~he
amount of curren~ supplied to solenoid ~7, the p~sition o~
pintle member 36 may also be inEinitely variea, thus ¦~
1 ~3 l6~ g
providin~ infinite variation of the amo-lnt of fluid flo~
being provided at the outlet. port 31.
As stated previously, a bypass valve structure C i~
associated with the pilot controlled mechanism ~. ~he
bypass valve C regulates the pressure differential acrosS
variable orifice valve ~ If this bypass valve ~ere not
included, a change in the size of orifice ~-would be
accompanied by a change in the pressure dlfferential
across it. This change in the pressure di~ferential.
ac~oss the orifice would at least partially counter the
change in flow which would have resulted, had the pressure
aifferential remained fixed. This is particularl~ true i~
the embodiment presently being aescribed, since pump 1~ has
a ixed aisplacement output at any given pump speed. The
pump would therefore try to force the samP amou~t o fluid
f~ow through the variable orifice ~, regardless cf the
size of the orifice F, unless some other pa~h were .
- ,
p~ovided t~ shun~ excess fluid ~low away from the variab-e
ori~ice F. Bypass valve C serves this func~ion.
Fig. 3 is a cross sectional illustra~ion ~f the
bypass v~lve C. The hypass valve includes a cartridye 38a
which is threadedly received in the-housing 11 The.
:
~ ~ : cartridge 3Ba has threads 6~ thereon which coopera~e with .
:: .
corresponding threads in the housing 11~ A spGol valve
~ : member 61 is located in a bore 62 in the cartridge 3Ba~
:. ~ , ' :
~ ;~ , ' '
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... .... .. .. . . . . ... .,, _. , . _. ,. _ ., . . , . .... ... , . , . . .. _ ._ _ ._ _ _ . , ., . _ _
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I~S shot~1n irl ~i~. 1, the l~f~t end o~ the cartrid~3e 3~ n~l
therefore the lef-t end face 63 of the spool 6:L,
comnnunicates ~it~- the outlet charnber 33 and accor~linsl~
outlet pressure acts on this face 63 o~ the spool va~vc~ -
61. A spr ing 64 is located in a chamber 65 a~: the r ight
end o~ the spool valve ~2, as viewed in the arawings, and
biases the spool valve 61 toward the lef t~ When the pump
is not operating, s~?rlng 64 ~iases spool valve 61 againSt
a snap ring 66 located in an interior annular groove
within the bore 62 of cartridge 38a.
As the pump be~ins operating~ fluiæ pressure in the
chamber 33 will act c:n the face 63 t>f the sp~ol valve
member 61. Further, a pressure tap, which is .in~ic~ed by
~he dotted line 67 in Fig. 1, and which is shown in cross
section at 68 in ~ig. 2, communicates ~he pressure from
down5tream of ~he variable orifice (i.e. the pressure in
the outlet port 31) to the chamber 65. T~e passage 6
communicates with an annulus 69 forme~ in the outer
periphery of the cartridge 38a. Restricted passages 70
com~unicate the annulus 69 w;th the chamb~r 65.
From the above, it shouXd be apparent ~hat the
pressure drop across the variable orifice ~ is
communicated to, and acts across the spool valve 61.
Speci~ically, the pressure in chamber 33 ~upstream of
ori~ice F) acts directly on the face 63 c~ the spool .
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,
1 ~3~
-16-
valve, whereas the pressure on the downstream side of
orifice F is communicated to the chamber 65 and acts on
the right end surfaces as viewed in the drawings of the
spool valve. Accordingly, the spool valve 61 will move in
bore 62 to a position wherein the pressure drop which
occurs across the variable orifice F balances the force
generated by the compressi~n of spring 64.
The position of spool valve 61 within bore 62 controls
the amount of fluid which is bypassed from chamber 33 to
the inlet port 30 of the pump. Thus, cartridge 38a
includes passages 71 which communicate with the inlet to
the pump by passages 39 (Fig. 1). In Fig. 3, the spool
valve is illustrated as occupying a typical control
position, wherein the spool valve has partly exposed the
passages 71 in the cartridge 38a so that a portion oE the
fluid flow may be bypassed from chamber 33 to the pump
inlet 30 via the passages 39. Because of the operation of
this bypass valve, the pressure drop across the variable
orifice F will not undergo a major change as the size of
the orifice is varied.
The bypass valve structure C also includes a ball
check relief valve which is shown in the drawing. The
structure, and operation of this valve will not be
described herein in detail since it is fully described in
the aforementioned U.S. Patent No. 4,099,893 and forms
~ ~ 5 ~ ~
-17-
no part o~ the pr~s~nt applicat;on. When ~he pre~S~r~ in
chamber 65 increases to a point where the balL moves ~f~-
its seat, chamber 65 is vented~ When chamber 65 is v~,~te~
the spool 61 moves to its full bypass position bypassing a
maximum amount of fluid.
There is illustrated in Fig~ 4 a cross sec~ional
illustration vf the solenoid 47 which positions ~he pilot
40. As seen in Fig. 4, s~len~;d ~7 includes a coil farm
8~ upon which a coil 81 is wound. An outer casing ~2 is
secured over the coil windin~s 81, A washer 83 and a-nut
~4 which is threadedly received onto the pole piece formea
by one end 8Sa of the coil Eorm 8Q hold the casing 82 from
m~vement in one airection (the left in E'ig. 4) relative to
the coil ~orm 80. The casing is restrained from movement
in the opposite direction (the right in Fig. 4) by
, . ~
engagement with a flange 80a on the coil form.
Coil ~orm 80 includes a cylindrical passage-85 which i
receives a correspondingly shaped armature 86~ Pilot
member 40 is attached to armature 86, and is thus movable ,
therewith. Armature 86 is resiliently biased against a
seat 87 located at the rightward end thereof, as shown in
the drawinys, by a spring 88. This results in creation of
an air gap 89 be~ween an end surface 8~a of the coil fo~m
and surface 90 o~ armature 86. The passage as is partially
defined by a sleeve 85b of nonmagnetic material located to
... _ . _.. .......... ..... .
31~5 ~
deine the air gap ~. The otl-er parts of the coi~ fo~r~
are magnetic. The slee~re 85a function5 to force the
magnetic lines of flux to f.low across the air gap r~th~
than around it.
The arm~ture 86 is pressure balancea ~y prov ia ing .
longitudinal grooves 31 which communicate with cham~er 89
and an annular groove 92 in seat ~7- This annular groove
g2 communicates with chamber 42 (~ig. 1~ ~ means oE
passages 93 formed in seat 87. Consequently, when the
armature 86 is o~ seat 87, the pressures on opposite ends
o~ the armature 86 will be equal and will thus have
substantially no effect on the positioning o the
armature. The positioning o~ armature 86, and thus of
pilot valve 40, will there~ore be entirel~ determined by
the electromagne~tic action of coil 81 acting in OppOSition
-to the resilience of spring 88.
Variable positioning of armature 86 is achieved by
connecting the leads 95 of coil 81 to a suitable variable
current source 96, illustrated in Fig. 4 as a voltage
source 97 connected in series- to a potentiometer 98. When
no current is supplied to coil 81, spring 88 will bias
,
armature 86 against the seat 87, which is restrained
against movement (rightwardly in Fig. 4~ by a snap ring
94. As current is supplied to coil 81, the
electromagnetic ~ield produced thereby will araw the
.
.
- -19- ~
;~
arma~ure ~6 back witllin t~le cy]indrical passag~ ~S a~ ;t
the res;].ience of spring 8~, until the force o~ the spri~3
88 just bal~nces the electromagnetic ~orces on the
arma~ure. By vary;ng the setting oE potentiometer 9~ so
as to chan~e the amount of current supplied to coil B-,
armature 86 (and conse~uen~ly pilot valve 40) can be
infi~itely pos;tioned over a pxedetermined range o~
pos;tions. Since the position of pilot valve 40 controls
fluid flow, the fluid flow will be ~irectly related to the
magnitude o~ the current signal. In other words, for each
set~in~ of potentiometer 98, pilot valve 40 and pintle 36
will assume known corresponding positions, ~nd a known
fluid flo~ rate will result. The flow rate may thus be
selected simply by placing potentiometer 98 at an
appropriate setting.
. -:. . .. .
There is illustrated in Fig~ 5 an embodiment o~ the
present invention, wherein the variable ori~ice.ana the
bypass valve are constructea in an assembly 1~0 which may '
be located remote rom the pump~ As shown in this figure,
the assembly 100 includes a housing having an inlet port
110, a work port 112, ana a bypass p~rt 114 in
communication with the pump inlet. The fluid passes rom
the inlet port llO to a passage 115 which communic~tes
with a second passage 116. Passage 11~ communica~es with
a variable orifice 117 defined by a valve seat 11~ and a
_ . , . . .. .. . ., .,, . _, _ _ _ _ .,, ~ _ _ _
16 3 l ~
-20-
pintle Inemher 119. The openin~ of the variable o~ c~ is .
controlled by v~rying the position of pintle member 1~3.
As in the embodiment of ~i~. 1, pin~le mem~er 11~ is
positioned by means of pilot member 120 coacting wit~ a
passage 121 in the pintle member 119- Pas5age 121 serves
to communicate f~uid pressure from chamber 122 bac~c to the
work port 112. Chamber 122 is 5upplied with fluid by
means of a passage 123 containin~ a flow restriction 124
therein. Pilot mem~er 120 is positioned rela~ive to
passage 121 by varying the current su~plied to a solenoia
12 This alte~s ~he pressure w.ithin chamber 1~2j thus
effec~ing the infinite positionin~ oE the pin~le mem~er
113. Also, the pressure drop across ori~ice 117 is again
maintained substantially constant by means of a bypass
! valve, indicated at 126.. This bypass valve may be
essentially identical to that shown in ~ig. 3, Thusr
pressure at the inlet side of orifice 117 is communicatea .
to one end o~ the spool valve of ~he bypass valve 126 by
means of passage 115~ w~ereas fluid pressure at the o~tle~
side o~ variable orifice 117 is communicated to annulus
127 ~ means of a passa~e 128. This pressure is
communicated to one end oE a valve spool as in the
embodiment o~ Fig. 1. This pressure diEferen~ial con~rols
the position oE the spool member, and thus also controls .
the selective bypassing of fluid from the inlet port 1l0
to the bypass port 114.
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. .. .... _ .. _ .. _, .. ~.. ,.. ..... _ .. , .. .. ... _ . _ . ____.~.~ .~__ . _. -
3 1 ~ 5 ~ ~ ~,
It sho~.lld thus be appr~ci~t~d t~at a ~lo~ control
mechanism has been tlesc~ibed wherein the ~lot~ throug~ ~n
ori~ice is in~initely varied by chan~ing the posi~iOn of
pintle member, and wherein the position o ~he pîn~l~
member is varied by varying the fluid pressure applied ~o -.
one end thereof~ ~urthermore, this ~luid pressure is
varied by means of an electromagnetlc solenoid which
infinitely varies the position of a pilot valve Jith
respect to a pressure discharge passa~e carried in the
: pintle member.
Figure 6 shows a further modifica~ion o~ the present
invention~ Fig. 6 illustrates schema~icall~ a valve stack
having individually actuatable valve assemblies 200, 20~ ~
etc. or controlling flow from a single fixed aisplacement .
pump 20~ to respective working mo~ors ~no~ shown).
'', ~
Flow ~rom the pump 204 to the valve stack is ~rough
a single unloading valve 206. Flow from ~he unloa~ing
valve 206 is direted to the inlet 2D7 of valve assembl~
200 through conduit 208. A branch condui-t 210 direc s
~low rom ~he unloading valve to the inl~t of valve
assembly 202. Thus, the valve assemblies.~00, 202 are in
parallel.
Each valve assembly has the construc~ion o~ ~he valve
assembly 200. The valve assembly 200 includes a
directional control valve 212 which directs fluid ~rom a
; 3 ~ ~
-22-
conduit 213 t~ and frorn a p~ir of ~rkin~ ports 214, 215
connec~ed to opposite chambers of a fluid motor ~not
shown) . In the pos it ion of the v~lve 21~ shown in ~i~. 6,
flo~ is directed frorn conduit 213 to ~orking port 21t;, and
flow from the other working port 214 is directed to ~he
reserv~ir 21~ by a passage not shown4
A flo~ control mechanism 220 ;s located upstream o~
the directional control valve 212. The ~low con~rol
mechanism 220 comprises a fixed opening 222 formed in ~he .
valve housing 223 and a pintle member 224 m~vable ~owara
and away from the ~ixed opening.222. The pintle member
224 includes a conically shaped end portion 225 which is
movable wi~h respect to the fixed opening 222 to form a
variable flow con~rol vrifice.
A-pressure compensating flow control valve 228
upstream of the flow co~trol mechanis~ maintains a ixed
pressure drop across ~he flow control orifice. ~alve 228.
comprises an axiall~ movable valve element 23~ which is l
biased by a spring 229 to an ~pen posi~ion directing flui~. i
; from the inlet 207 to the ~ain 10w control orifice~
Fluid pressures upstream and downs~ream of the flow
control orifice act across the valve 228 to prvduce a ,
fluid pressure force in opposition to bias o~ spring ~29,
Thus, the valve compensates for fluid pressure variations
at the valve inlet 207 to maintain a fixed pressure drop
across `he flow control orifice~
.
I ll S31~5 ~ ~
-23-
~ s with the previou~s e~bodiment, a flu~d preSsu~-e
di~ferential acts across the p;ntle member 224r and a
solenoi.d 227 ;s opera~ive to infinitely vary the pOSiti~n
of the pintle 224 relative to the opening 222 to vary the
size of the flow control orifice. Flow upstream o~ the
flow control orifice acts on the conical end 225 of the
pintle 224. A conduit 226 directs a ~ow o fluid th~ough
a fixed restriction 219 and into a fluid chamber 240
formed at the other end of the pintle 224. Further, a
passage 2~2 is formed in the pintle valve and extends from
chamber 240 to the downstream side of the flow control
orifice. In a manner similar to the previous emboaiment,
the solenoid armature includes a small pintle 241 which is
movable with respect to the passage 242 to vary the
pressure in chamber 240. This varies the pressure
differential across ~he lar~e pintle 224 and effec~s .
movement o~ the large pintle relative to the f ixed opening
222 to control the amount of ~luid which flows to conduit
~13, and which is directed to one of the working ports ~y
the directional control valve 212~
The position o the directional control valve 212 is
also controlled by a solenoid 245. When the solenoid 245
is in a de-ener~ized condition a fluid chamber 248 on one
s;de of the directional control valve 212 communicates
with fluid at system pressure (by me~ns not shown). When
'
l G ~
-2A-
c~amber 2~8 is at system pressuce th~ :Eluid pressure Tn
the val.ve element against the bias oE a sprin(~ 250
upward.ly as shown in Fi~ure 6 and fluid is direoted feo~
conduit 213 to working port 216, and working port 214 is
communicated with thQ reservoir 218 When so~enoid ~45 is
energized it operates to vent chamber 248 to the reservoir
218 thereby allowing spring 250 to move the directional `
control valve 212 to the other operating position in which - :
it directs fluid from conduit 213 to working port 214, and
communicates working port 216 with reservoir 218,
In the position shown in Figure 6, t~e solenoid 227
is in a de-energized condition~ Small pin~le 241 is in a
position in which it closes ofE orifice 232, and the
resulting pressure build-up in chamber 240 results in the
pintle member 224 closing the fixed opening 222. This
,: . . ....
results in all system flow being directed to the other
valve assemblies 202, et~. When solenoia 227 is energized
fluid pressure in chamber 240 is reduced and the pressure
-
dif~erentia~ across the lar~e pint~e valve 224 moves the
valve to a position allowing a controlled amount of fluia
to flow thereby. The valve 228 operates ~o maintain a
fixed pressure drop across the 10w control orifice .
despit~ pressure variations at ~he inlet 207. The
direction o~ flow to one working port is c~ntrolled by
either de-energiz;ng or energizing the solenoid 245.
- . .
~ ~ 1831~5 ~ I
-~25-
~ n a s;milar m~nller, each valv~ assembly 200, 202,
etc. is controlled by a pair of s~le~ ds to control tile
amount and direction of fluid flo~ therethr~ugh. o~
co~rse, while two valve assemblies 200, 202 are 5hown~ the
invention can be practiced with differen~ nurnber5 of valve
assemblies.
The unloading valve 206, which control5 the flow to
the ~alve system, also operates to divert some fluid to
reservoir in proportion to an unloading pressure. In the
disclosed embodiment, the unloading pressure is set in
part by the highest working port pressure. System
pressure co~nunicates with a chamber 25~ on one Siae o~
the unloading valve element 254 to urge the valve element
in ~he one direction. A ~luid pressure in a con~uit 260
co~nunicates with a chaTnber 262 on the other side o~ the
:
valve element 254. ~ spring 256 disposed in chamber 262
also acts on the valve element 25~r ThusJ the difference
between the pressure in chamber 250 and the c~mbined fluid
pressure in chamber 262 and the force of spring 256 sets
the unloading pre~sure.
The fluid pressure in conduit 260 communica~es the
hi~hest working port pressure in the system to chamber
262. A pilot flow of fluid from the do~nstream side of
the ~low control orifice of each valve assembly
co~nunicates with conduit 260 through a respective check
.
;3l6~ ~
-26- .
valve 2~4. The hi~hest working port pressure coTnmuni
with concluit 260, while maintainin~ all other check valvcs
264 closed. Thus, the ~nloac1ing pressure app~ied to valve
element 254 is in proportion to the hi~hest working port
pressure of the system. .
A further embodiment oE the present invention is
shown in Figure 7. ~he embodiment of ~igure 7 functions .
in the same manner as the embodiment o~ Figure 1.
~owever, the flow control va].ve in the embo~i.ment of
Figure 7 is in a compact cartridge form.
The embodiment sho~n in Figure 7 inclu~es a pin~le
member 3D0 and a pilot member 301. The pilot member 301
is.press ~it into an armature 31~3 which is moved by a
solenoid 302~ The pilot member 301 is biased ~ a spring
303 into engagement with the pintle 300, as shown in ~ig.
7, when the solenoid 302 is not energized. ~hen the
solenoid 302 is energized, the pilot member 301 will move
awa~ from pintle 300. This provides for ~luid . l
communication between the chamber 305 and the outlet - :
chamber 306 through the passageway 307 in the pintle
member 300. As shown in Figure 7, a suitable fluid Elow
passageway 310 ~shown in Fiy 7 out o~ position to
simplify the drawing) is provided for directing the pump
output pressure into the chamber ~05 An orifice 311 is
located in that passageway The orifice 311, of course,
functions in the same manner as ~he ori~ice 45 in the
embodiment of Figure 1.
., . .. .. .. . , ,, , , ~
3 ~ ~
27 -
s~litable g~lide m.ernbe~ 31S is connected witll a c~;l
~o~rn 316 and extends int~ a p~;sa~e~ay 317 in the armature
318. Suitable bearin~s 321 are provided between the ~uicle
member 315 ancl the armature 318 so as to guide movement OL
the armature.
When the coil 302 is energized~ lines of flux are
directed through the air gap 320 and attract ~he armature
318 toward the surface 323 of the c~il form. A sleeve of
nonmagnetic material 32~ is interposed in the coil form,
which is otherwise magnetic, so as to concentrate ~he
lines of flux so that the~ extend throu~h the air ~ap 320.
The spring 303 which biases the armature 318 and the
pilot member 301 towara the pintle member 300 acts between
a wear disc 330 which is mounted in place on the coil form
by a snap ring 331 and a spider 340 whicn is mounted in
place on ~he pintle by a snap ring 341~ The spi~er 34~ -
has openings which provide for ~luid-communication be~ween !
the opposîte sides thereo~.
The pintle member 300 in the embodiment of ~igure 7
is a ~omewhat dif~erent construction than the pintle
member of the other embodiments. ~owever, detai~s o~ i~
will~not be described, since they are readily apparent
from the drawing. The pintle mem~er 300 is provided with
a series of stiction grooves 343 on the outer peripher~
thereof which minimi7.e the possibility that the pintle
........... , _
ilB3165 0 . ' ~
-2B-
member ~ill stic~:. Tilese (~rooves 3~i3 enable the pin~
member to m~ve easi~y.
As note~ above, the Fi9ure 7 embodiment primarily
di~ers from the o~h~r embo~iments in ~hat the assembly is
a cartrid~e-t~pe assembly that can be readil~ secured in
the housin~ o the pump or unit in which it is located and
thus can be easily replaced or assembled i~ the housing.
Specifically, all of the elements described are Suppor~ed
on a common member 350. At the left e~d of the member 350
is the solenoid 302 which is suitably securea thereto.
The coil form 316 projects into the member 350 and is
suitably secured therein as by means of a threaded
c~nnection therewith, designa~ed at 352. The righ~ end of
the member 35~ is threade~ at 355. This threa~ed
projection 355 screws into the pump housing 360.
Accordingly, b~unthreading the member 35Q from the
housing 360 the entire assembly of the solenoid and the
control valve can be removed for either repair, or
replacement.
. Although the invention has been aescribed with
respect to a preferred embodiment, it will be apprecia~ed
that various rearrangements and alterations of parts may
.
be made without departing ~rom the spirit ana scope of the
inveAtlon, as defined h~rein.
.
~ .
