close

Вход

Забыли?

вход по аккаунту

?

код для вставки
Feb. 1, 1949.
Q_ R, ALDEN
HYDRAULIC SYSTEM
Filed oct. 11, 1943
- 2,460,440
¿aan
y Patented Feb. 1, 191,49
>UNITED STATES PATENT ' OFFlC4
2,460,440
HYDRAULIC SYSTEM
Carroii R. Alden, Detroit, Mich., assignor to Ex
Ceil-Ü Corporation, Detroit, Mich., a corpora
tion of Michigan
Applica-tion October 11, 1943, Serial No. 505,799
(El. Gil-«52)
12 Ciaims.
~ ,
l
operation, an arrangement effective at will to
The invention pertains to improvements in hy- V
condition the governor valve for use in main
taining the pump discharge pressure at a pre
draulic systems, and more particularly to a novel
control arrangement for the same.
One object of the invention is to provide in a
Si
hydraulic >system having'high and low'pressure
sides, 'a novel‘arrangement forimaintaining the
high pressure side of the system either under
a. .predetermined relatively high pressure or, al
ternatively, dropping the same to `a low value,
as may be desired.
,
'More speciiicallyy it is an object of the inven
“oir” position.
Still another object is to provide a hydraulic
system embodying a novel safety arrangement for
10, disabling the normal controls in the event an
actuator stalls and in such manner that the
tion ‘to‘provide in ahydraulic system embodying
a pumpas a source Vof pressure fluid and a main
control valve vfor controlling the flow of fluid
to a main actuator, a novel arrangement for op
tionally maintaining the pump discharge under
substantial pressureA or not, as may be desired,
when the main control valve' is shifted to its neu
tral or “oiî” position.
selected value whenever the main actuator stops,
whether such stoppage results from stalling or
from shifting of the main control valve to'its
»
The optional maintenance of pump discharge L
under predetermined'pressure or atsubstantially
low pressure when Vthe main actuator is stopped
very substantially enhances the eñiciency and
potential i’ields of use of the system under differ
ent operating conditions. In the'event that the
supply of viluid to the system must thereafter be?
stopped before the actuator can be restarted.
Further objects and advantages of the inven-tion will become Vapparent as the‘following de
scription proceeds, taken in connection with the
accompanying drawing, in which:
l Figure l is va generally schematicY representa-‘
tion of a hydraulic system embodying the present
invention.
'
Fig. 2 is similar to Fig. 1, but shows a modified>
form of hydraulic system -also embodying'the
present invention.
g'
„
'
`
ì
VWhile the invention is susceptible of various
e2 modiñcations and alternative constructions, I
have shown in the drawings and will herein de
pump is being used not only asV a source of fluid
scribe in detail certain preferred embodiments,
pressure Y’for a main actuator, 'but also as such
but it is to be understood that I do not'thereby
source for some auxiliary device or other actuator,
intend to limit the invention to the speciiic forms
it is requisite that the pump output pressure be
y disclosed, but intend to'cover all modifications
maintained if continued use of the auxiliary de
and alternative constructions falling within the
vioeis to be possible during those intervals dur
spirit and scope of the invention as expressed in
ing which the main actuator is stopped. On the
the appended claims.
`
other hand, mere maintenance of pump output
Referring more particularly to the embodiment
pressure at all times, irrespective of system de
i of the invention illustrated in Fig. l, the system
mand, is inexpedient and highly inefficient be
there shown comprises a pump lû as a source of
causeof the frequent waste of power input for
pressurefñuid, such as oil. This vpump is de
¿the pump which results.> Thepresent invention
sirably
arranged to deliver fluid at la substan
oomprehends the use of va simple selector for con
tially constant volumetric rate and may be- of
ditioning the system either for pressure main
tenance or not, just as may be desired, during the
“oit” periods of the main actuator.
I
`
` .A more specific object oi the invention is to
provide a hydraulic system in whichaï'pressure
operated diverting or governor valve is arranged
notionly to divert pump discharge in accordance
with the pressure drop -across a restricted oriñce
in the actuator exhaust line during normal oper
ation-of the actuator, but in which the governor
valve may also be conditioned at will to divert
iiuid _in the course of maintenance of a predeter
mined> discharge pressure for the pump while the
actuator is stopped.
_
vAnother object is toprovide ina system em
ploying a governor valve operable as noted vin
f either the well-known vane type or gear type.
Fluid from they pump is delivered, under- the con
trol of a main valve ll, to a main actuator l2
consisting of a cylinder I3 and lpiston Ill. Such
actuator may drive any movable element de
sired, and in the present instance it'is contem
plated that the cylinder i3 be stationary, the pis
ten lâ being shown as rigidly connected to a
movable machine tool table l5.
`The main valve li may take'> various forms. 1n
the particular construction illustrated, it serves
not only to control the stopping and starting of
the actuator l2 but also its direction of move-V
ment. The valve shown is of the sliding plunger
type `and comprises a plunger it ‘slid-able ,end
the preceding statement of object during normal ÖS wise within a suitably ported housing li. Atthe
3
2,460,440
4
center of the plunger I6 `are two lands or collars
I8, I3 separated by an annular channel 26, while
at the opposite sides of these two central collars
are two further collars 2I and 22 separated from
45 becoming less and less restricted by the gov
O-rnor
valve as the latter is shifted progressively
to the right. To subject the valve element 42 to
the pressure drop across the restricted orifice
de, connection is established from the exhaust
the adjacent central collars by respective an
nular channels 23, 24. Annular end channels 25,
26 separate the collars 2|, 22, respectively, 'from
the end portions of the plunger I6. Pressure iiuid
is delivered by the pump lll into its discharge or
line 33 on the upstream side of the oriñce 40
through conduit 43 having a restriction 49 there
in, an annular passage 5l? inV a pilot valve 5I,
whose purpose will later appear, and a passage
outlet line or conduit 21 from which it passes
52.
through branch conduits 28, 29 and 30 so that
:duid from the pump is supplied to the main valve
' With the orilice and governor valve 40, 4I ar
ranged as describedany tendency of the actuator
II through ports at the spaced termini of the
ii'. to slow down will result in a diminution in
three conduits 21, 29 and 33.
the new of iiuid through the orifice 4S and con
Opposite ends of the acuator cylinder I3 are
sequent drop in pressure across the same. This
connected to the main valve II at spaced points 15 ' l cause the governor valve element 42 to shift
through conduits 3l, 32, while a return or ex
to the left under the urge of the spring 41, there
ha-ust line 33 to the reservoir 34 is connected to
tending to diminish the amount of the fluid
the bore of the main valve through three spaced
diverted through lines 45, 46, so that the de
passages or branches 35, 36 and 31.
livery oi fluid from the pump to the actuator
When the main valve plunger I6 is in the 20 is correspondinglyincreased, thus increasing the
neutral or “off” position shown, midway in its
actuator speed. Conversely, if the actuator i2
path of travel, the flow of fluid to the actuator
tends to over-speed,l the amount of huid exhaust
I 2 is blocked by collars 2I, 22 and the fluid dis
ed >iron; it wili tend to increase so that the pres
charged from the pump ?lows through conduits
sure drop through the orifice 43 is correspond
21, 28 and 30, thence through the central chan 25 ingly increased and the governor valve element
nel 20 in the valve, and through the passage 35
thus shifted io the right to divert a cor
into the exhaust line 33, through which it re
f- iondinglyincreased amount of fluid from the
turns to the reservoir 34. The inlet 38 of the
pressure line 23. This results in a slowing down
pump I0 is also connected to this reservoir.
the actuator by reason oiA the diversion of
Upon shifting the main valve plunger i6 to the 30 ñuid which would otherwise pass through it.
right a distance substantially equal to the width
ln this manner the speed ofthe actuator is pre
of the land 22, pressure fluid discharged from
ciseìy and accurately governed with a high de
the pump I0 is supplied through conduits 2?, 23,
gree of sensitivity despite fluctuations of load
29, and thence through groove 25 and conduit
which may be encountered.
.
3I to the left end of the cylinder I3. At the same 35
time, :duid is exhausted from the opposite end
of theY cylinder through conduit 32 and groove
In the system as so far described, when the
valve li is in its neutral position shown, fluid
from the pump lll is circulated back to the reser
24, into passage 31 and exhaust line 33 so that
voir 34 with substantially no restriction to ilow
the piston I4 moves to the right. Conversely,
except that oifered by the orifice 4D and the small
40
when the valve plunger I6 is shifted to the left
amount caused by the back pressure valve 39;
from its mid position shown, pressure ñuid is
In the event that the governor valve 4i is made
supplied to the righth-and end of the cylinder I3
sensitive through the use of a light spring 41, as
(through 21, 2B and 32), while ñuid is exhausted
is desirable for maximum sensitivity in its gov
fromthe lefthand end of the cylinder'I3 (through
45 erning operation, the pressure drop across the
3|, 23, >36 and 33) so that the piston i4 moves` in
restricted oriñce ¿i0 will be quite small. In such
the opposite direction, that is, to the left. The
circumstances, the pressure at the pump outlet
collar I8 or I9, as the case may be, blocks the
passage 35 upon shifting of the valve plunger I6
1 will fall to a low value when the main valve I l
is shifted to neutral. Although such diminution
to either right or left. If desired, a back pres- 50 in pump discharge pressure is desirable from the
sure valve 39 of conventional spring loaded type
standpoint of minimizing power consumption for:
may be interposed in the exhaust line to the
the pump while the main actuator I2 is idle, it
reservoir.
'
may in some circumstances be highly undesirable
The speed of the actuator I 2 in either direction
as, for example, when a branch line 53 is led oil'>
of movement is controlled by an adjustable re 55 the pressure line 21 for supplying various auxil
stricted orifice 40 operating in conjunction with
iary devices (not shown). By way of specific
a governor valve 4I. The restricted orifice 40 is
example, there may, in a machine tool, be various
interposed in the exhaust or return line 33 from
fixtures, clamps or the like which are arranged
the actuator and meters the fluid out of the
to be actuated by. fluid pressure derived through
actuator during either forward or reverse move 60 the line 53.
In such case, it may be'requisitek
ment of the latter. The governor valve 4I, on
that iluid pressure be available in the branch
the other hand, comprises a valve plunger ‘l2
line 53. at a `predetermined fixed value at some
having an annular channel 4.4 therein and slid
times for operation of the auxiliaries, while at
able endwise within -a casing 43. A diversion or
bleed passage 45 leads to the governorïvalve Iii v65 other times when the auxiliaries are not in use
efficiency is best served by permitting the dis
from the pressure line 28 and connection to the
charge pressure of the pump to fall to a low value.
exhaust line 33 is completed through a passage
in accordance withv one aspect of the present
46. A compression spring 41 yieldably biases the
invention, provision is made for selectively con
valve element 42 toward a position in whichit
blocks connection between the passages 45, 46. 70 ditioning the system to maintain, at the option
oi the operator, either a relatively high predeter
Upon application of suñìcient pressure to the left
mined pump discharge pressiu'e or to drop such
end of the valve element 42, it is shifted to the
pressure to a negligible value when the main
right against the bias of the spring 41 for con
valvey li is in neutral. VIt is for this purpose that
nection of the passages 45, 46 through Vthe chan
nel 44, such connection between the passages 45,
ahand operated selector valve 54 and the pilot
valve 5I are included in the system. '
' '
"
'.Tlie Agenera-1' ìiun'ction. lof V4itl're selector valve' «lill-k
Y pilot Valve-is set "the latter opens, thereby in turn
i's `to ldisestablisli or'fblock. "the zsubstantially„free
ñowoi .fñuid discharged from' `the fpunip ï:bach yto
til-e> ‘reservoir’ " through only -:the 'slight vrestrictioh
of the ‘orifice All. >»0n 'the i other hand, ¿the gen
eral Liunction foi `~ the :pilot valve "5l, in the‘system
illustrated . in'l‘lig. »#1, is to fout ’ofi ¿the Avconnection
oí "the governor "valve 'flfl through `the 'passage §48
tortue' upstream side‘oí ¿the orifice-‘60, 'and :to: com f
neet theigovernor -valve_~ directly ato'fthe `disclria'rge
side foi theïpump throughlinesf'âland 28v when
tion.
~
.~
.
l
opening thegovernor'r valve to divert fluid, so that
the pump-pressure ris limited to the value prede
terminedby the spring loading of the pilot valve.
Such safe pressure, Aand no more, is thus applied
to `move the stalled actuator.
.
From the foregoing, it will be seen that by
merel-y throwing the selector valve 58, the sys
tem'can‘be Conditioned at'will either to cause the
pump» l0' to continue to deliver ilu-id at high pres
surefffor use in auxiliaries or the like when the
main valve ll is inneutral, or alternatively con
ditioned. to cause the pump voutput to be recir
.
Theëpilot’valve 5l ‘.coniprisestëaf. longer Vlil» ïhav
culated 'at lov.7 ‘pressure with consequent low
ing therein the annular "channel 250 I noted, such
power consumption in the event that there is no
occasion to use any‘output pressurev from it when
inte >>the¿position vshown' :in ~~which itlieiclianiiel.~v l251i.
interconnects the lines Miami 52, The ipurnp
discharge „pressure is applied directlyr to> the
the’main valve is in neutral. Moreover, in ~either
position ofthe selector valve 5è, safely limited
limited pressure is 'available to break loose the
jam should the actuator stall.
plunger ¿being urged byfa compressionbspringlêäâ'
righthandf end‘oi'thezplungerfäâ from’ the jlin'e '28.
AWhen thefselector valve 1554, which is :a `¿two
`position*oil-'foiî valve, Sis .shifted from its fopen
position Vïshoivri to `its î'optionally 'available closed
positiomit` blocks >the -iî'ovv‘y offrit-iid from theout
VBy way yof analysis, it Will be noted that there
are in effect ñrst and second alternatively avail
able relief passages from the outlet of the pump
~ when-the main valve il is in neutral.
One such
passage returns to the reservoir 36 by way of the
exhaust line 33 :and the other by way of the gov
ernor valve under the control of the pilot valve.
Closing the=selector valve 5d cuts off the riirst
mentioned .passage by Way of the exhaust line
and compels the fluid to go through the other
-36
ward 'shift 4of.tlf-1e¿pilot -valvesplunger :blocks ¿the
l’et'of äthepump into fthe exhaust fline :33. In
consequence, Ãlznressure-ibuilds-rup ¿on-` .the .discharge
side sof'tlie pump l0 untilitfrea'ches 'a' value suffi
ciently high to-ove'rcomeèthe-'spring 56 :and thrust
thea-pilot valve plunger ‘55Íto y.the ï’leît. . .'Suchfleft
line ‘48 vand ’ opens Wcolrin'umication'between 'lines
ZE-and 52. ’ The resultant-application fofipressure
to 'the .-leit‘end -of the governor valve-plunger 142.
shifts ~`the latter ‘tothe-right vso "that‘lfluid fis .idi
verted’from the ipump :outlet through passages
55,46. ‘In this >way duid .is‘fdiverted î'from trie
Y outlet fof‘îthe .pump through the governor valve
Vbutat> a .pressure yd«terniined -by the springiset
ting of the..pilot'valve’f5l. Byßadjustrnentfof?the
springfloading for ltheupilot »va1ve,‘discharg‘e pres- -
sure of fthe'fpump :l0 -may'thus be--maintainedat
any »desired value suitable :for actuation . of auxil
iaries orv the> like :connected :to Ilinef53.
j
It will, be observed "that-in utilizing >the 1ar
passage ‘by Way of the governor valve which is
controlled Vby 'the pilot valve to maintain the de
sired highpressure.
Y
-In Fig.' 2 >is shown a modified hydraulic system
also embodying the present invention The sys
temor Fig. -2`di?fers ‘in ‘a structural sense from
that-lof Fig-ffl primarily in that the pilot valve
5ta, corresponding Yto the pilot valve 5l, is
adapted 'to-cut oli positively the iiow oi huid to
tli'erestricted lorifice g1ML-in addition to perl-Torm
in'g i'tlriefotl-ier 'functions noted for the pilot'valve
5l'heretofore-described, »whenever the pump dis
charge î'p‘res'su're builds up suiiiciently to actuate
the pilot'valve. l»In an operational sense, this 're
may be thrown to its blocking positioniertfarit7
stilts ¿inY substantially ‘diiïerent characteristics
tlian‘ïtliose »heretofore described when the linain
time, as,»for example, while .the factuator "I2 is
in motion, without in‘a‘ny :way <-interfe`ring “with
the ¿remaining :parts of the system are identical
rangement-described above, thel selector-"valve ' 5t
the normal operationioffthe governor >`vvalve '41 vin
maintaining a‘coristant >feed .rate `for theia‘ctuator.
Whenr the i main vvalve >il ` is i either Y injits ï’n‘orinal
right'or le-i‘than'dposition:for-movement of ‘the
actuator 1l2,"the «passage V-35 is Y'b1oche‘d~fanyhovv
so :that .the opening or «closing pf ,the --selector
‘ valve 154 `rwill have `no immediate fei’fect'on "the »
operation of thesystem'so'flong ‘as ‘the'ac'tuator
adtuat'oi' -Í2 is stalled, all as detailed below. Since
Withï'those employed in the system shown in Fig,
i, ‘the 'saine reference numerals have been used
for v'theirïi'dïentiñcation, Vand a repetition of the
detailed :description ‘of f the same is unnecessary.
» 11n-this instance, the pilot valve 5in. has a slid
able Yplun-g’er V55a vwith two annular channels
therein, ‘50a ‘and-5501), the plunger being urged
tothe 'rlgh't'as ybefore by the compression spring
äâ.
this instance, the‘channel 59h is inter
posed‘in 'the exhaust 1ine3'3 on the upstream side
of 'thefres'tfricted oriñce ‘40, while the channel
liminarily condition the :system «iso >that upon ‘sub -'
sequent stopping of the actuator "l2, #either >Íby 60 lîßa‘i‘s interposed' between'a branch line 33a from
the eXhauStTlirie-ß and the passage 52 leading
stal-ling or `restoration ofthe mainivalve - 1 I . to
to ».the'ëgovernoi- _valve 4l. in consequence, when
neutral, the pilot valve 5| 'wil-l‘iminediately "be
the Apilot- >valve plunger 55a is shifted'to the left
come-effective to control ‘fthe opening' foffthe, gov
under 'the inñu'enceof pressure on Ythe discharge
ernor Avalve :for maintaining 'fa Y‘predetermined
high pressure fin k.-tl’ie-ßpuirip .discharge line. 65 side of'tliepuinp lll, it cuts oil vany Vflow of Vex
hai-'ist ‘ïñuid ‘from the line 33 into the restricted
_Should Ithe :actuator >l2 Vstall whilevîthe'selector
‘ continues to :move normally.
Closing îoi? 'the
selector "vali/‘eat such time'does, however, pre
va1ve~54 is closed, the-.governor'valve-llfl 'will-‘tend
to close «since-there is no lfurther pressure 'drop
across the orifice 4-0, >and pressure Will-build ‘up
in :the vpump discharge ëline. "Such »pressurek tends
i to shovethe V7actuator »aheadt'o 'overcome what=
ever‘obstruction caused it '-to’stall.> The pump
dischargepressure is,.however, limited toa safe
value by thespilot valve-5I l-for as soonifas the idis
chargepressure Vreaches the-'value for> which"V the
orifice '46, as -Well as interrupting the flow of fluid
from tlieflihe-SSïto the governor valve and con
necting "theïlatter lto the pump discharge pres
sure.
`
v When `the actuator ’I2 is moving normally, the
restricted orifice 4U and governor 'valve 4! coact
to govern its speed. in precisely the saine inan
ii’er-Iasdescr‘ihed ‘with reference to Fig. l, irre
spective >oflïtlie position :oi-thc kselector valve 54.
7
2,460,[email protected]
Similarly, when theactuator l2 'is'stopped by
shift of the mainY valve il to neutral', fluid'vvill
be circulated from the outlet of the pump back
to the reservoir'tt‘ with only the small restric
tion of the orifice ¿ii? in the event that the selector
valve 5d is in the open position shown. On the
other handit the selector 5t is closed,.when the
main valve is shifted to neutral, the pilot valve
51a will subject 'the governor vaivev tl to the pump
discharge pressure and maintain such discharge
pressure at the value determined by the setting
of the spring 56 of the pilot valve, also just as in
the case of the system shown in Fig. I.
The difieren-ce in operation between the sys
tems of Figs. l and 2 occurs when the ‘actuator
l2 is stalled with the selector valve 5e closed.
As has heretofore been described in connection
with Fig. l, stalling of the actuator l2 when em
ploying the latter system causes the pilotA valve
81?
tuator having an inlet' and an outlet, means'for
directing‘ñuid from .the pump to said actuator
inlet, a restricted oriñce interposed in the path
of ñuid exhausting `from the actuator outlet.
means deñning a iluid diversion passage from the
discharge side of the pump, a movable governor
valve member interposed in said diversion pas
sage'and'spring biased into a position to block
the same, means for applying to said governor
valve member the pressure acrosssaid orifice in a
direction to oppose said spring bias, and means
including a pilot valve for interrupting the ap
plication to saidgovernor valve member of the
pressure across said oriñceand applying to .said
Vgovernor valve member Vthe discharge pressure of
said pump, saidpilot. valve including a spring
loaded valve member subjected to the discharge
pressure of said pump.
‘
2. In a hydraulic system, the combination of
5l to render the governor valve d! operative to 20 a substantially constant volume pump, an ac
divert ñuid from the pump outlet in such man
tuator having an inlet and an outlet, means in
ner as to maintain the pump discharge pressure
cluding a main valve having on'and off positions
at a safe value determined by the setting of the
in which it respectively directs fluid from the
bias spring 5t oi the pilot valve. In contrast, the
pump to said actuator inlet and to exhaust, a
arrangement in Fig. “lis such‘that when the ac 25 restricted
orifice interposed in the path of iiuid
tuator l2 is stalled with theselector valve 54
exhausting
from the actuator outlet, means denn
closed, the pressure on the actuator piston I4 will
ing a iluid diversion passage from the discharge
be equalized and the actuator cannot be restarted
side of the pump, a movable governor valve mem
until the pump ill has been stopped and the pilot
ber interposed in said diversion passage and
valve 5in permitted to return to its , position 30
spring biased into a position to block the same,
shown in the drawings. Since the operator is
means for applying to said governor valve mem
thus compelled to give special attention to the
ber the pressure across said oriñce in a direc
machine by stopping the pump in the event that
tion to oppose'said spring bias, means including
the actuator becomes stalled, the safety of the
a pilot valve operable upon shifting thereof from
system is obviously enhanced.
35 a ñrst to a second position to interrupt the ap
Choice of the arrangement of Fig. 1 or Fig. 2
plication to said governor valve member of the
will depend upon Whether the particular machine
pressure across said orifice and to apply to said
in which the system is installed makes it more
governor valve member the-discharge pressure of
desirable to provide the safety stoppage arrange
said pump, said pilot valve being spring urged
ment of Fig. 2 when the actuator stalls, or the
to said Viirst position, means for applying the
continued application of limited pressure as in
discharge pressure of the pump to said pilot valve
Fig. l to free the actuator under like condition.
in a direction urging it toward said second posi
As to just what takes place in the system of
tion, and a selector valve for optionally blocking
Fig. 2 when the actuator l2 stalls while the se
or opening the flow of fluid from the main valve
lector 54 is closed, it Will be observed that in such 45 to
exhaust when the latter is in said off position
case the pressure will build up in the pump dis
therefor.
'
’
charge lines 21, 28 due to the immobility of the
3.
In
a
hydraulic
system,
the
combination
of a
actuator piston le. In consequence, the pilot
substantially constant volume pump, an actuator
valve plunger 55a is shifted to the left, thereby
blocking the 110W of ñuid from the exhaust line 50 having an inlet and an outlet, means for direct
ing fluid from the pump to said actuator inlet, a
33 to the restricted oriñce 4B, as well as to the gov
restricted oriñce interposed in the 'path of ñuid
ernor valve lil, and at the same time subjecting
exhausting from the actuator outlet„means defin
the governor valve 4l to the pump discharge pres
ing a fluid diversion passage from the discharge
sure. Under such circumstances, the pressure
on opposite sides of the actuator piston I4 is very 55 side of the pump,a movable valve member inter
posed in said diversion passage and spring biased
quickly equalized and the pump discharge pres
into a position to block the same, means for ap
sure is limited toI and maintained at, a value
plying to said valve the pressure across said orifice
determined by the setting of the pilot valve spring
in a direction to oppose said spring bias, and
5E. Once the pilot valve 51a has thus shifted, any
subsequent shift of either the main valve ll or 60 means for interrupting the application to said
valve member of the pressure across said oriñce
Aselector valve 5d will be ineffective to change the
and applying to said valve member the discharge
pressure conditions within the system, wherefore
pressure of said pump.
the actuator l2 remains at rest. To again set the ,
_ »
`
4. In a hydraulic system, the combination of
system in operation, it is necessary that the oper
ator stop the pump lil and thereby drop the 65 a iluid delivery pump and an actuator, a main
valve for cutting off the flow of iiuid from said
pump discharge pressure to a value such that
pump to said actuator when the 'valve isin an
the pilot valve 5Ia is restored to its initial posi
off
position therefor, means including a pressure
tion shown in Fig. 2. The operator is thus com
operated valve for maintaining the discharge pres,
pelled to give his attention to the machine and
is apprised of the fact that the actuator has been 70 sure of the pump at a predetermined value, and
selector means operable only when said main valve
stalled so that he may clear the obstruction which
is in its oil.’ position to render said Vfirst men
caused the stalling.
tioned means operative or inoperative at will.
v I claim as my invention:
- Y
' `5'. In a hydraulic system,` the combination of
1. In a hydraulic system, the combination of
a substantially constant volume pump, an ac 75 a iiuid delivery pump and an actuator, a main
valve for cutting off the new ci duid from said
2,460,440
position therefor, and means operable only when
the main valve is in said ofi position to retain the
pump discharge pressure either high or low.
6. In a hydraulic system, the combination of
a substantially constant volume pump, an actu
ator having an inlet and an outlet, means for
directing iluid from the pump to said actuator in
let, an exhaust line leading from said actuator
outlet and having a restricted oriiice interposed
therein, means defining a fluid diversion passage
leading from the discharge side oi said pump, a
movable governor valve member interposed in
said diversion passage and >spring biased into
position to restrict the same, and ,means includ
an actuator and means including a pump for Sup
plying pressure fluid thereto, of means operable
automatically upon stalling of the actuator for
not only preventing the supply of further ñuid to
the actuator from said pump but for also there
after retaining said actuator at rest until the
pump has been stopped and restarted.
10. In a hydraulic system, the combination
with an actuator and means including a pump for
suppiying pressure fluid thereto, of means in-cluding a valve operable in response to discharge
, pressure of the pump for effecting the diversion of
fluid from the pump outlet to disable the actu
ing a pilot valve operable in alternate first and
ator against further movement when the pump
discharge pressure reaches a predetermined max
imum value and for simultaneously blocking the
discharge oi fluid from said actuator.
11. In a hydraulic system, the combination
second positions thereof to apply respectively
the pressure across said orifice and the pumpdis
charge pressure to said governor valve member in
a direction such as to urge the same in each case
toward open position against said spring bias, said
pilot valve being adapted when'in said second
position thereof to block said exhaust line on the
upstream side of said oriñce.
7. In a hydraulic system, the combination of a
substantially constant volume pump, an actuator
with an actuator and a source of pressure'?luid
therefor, of means operable in response to the
,
having an inlet and an outlet, an exhaust line ‘
leading from said actuator outlet and having a
restricted orifice interposed therein, means in~
cluding a main valve operable in alternate posi» ~
tions thereof to direct the now of ñuid from the
pump to said actuator inlet or to block such in
let and direct the pump discharge to said ex
haust line, means deñning a fluid diversion pas as
Sage leading from the discharge side of said pump,
a movable governor valve member interposed in
said diversion passage and spring biased into
position to restrict the same, means including
a pilot valve operable in alternate first and sec
ond positions thereof to apply respectively the
pressure across said orifice and the pump dis
charge pressure to said governor valve member
and in each case in a direction to urge said gov
ernor Valve member toward open position against
said spring bias, said pilot valve being adapted
when in said second position thereof to block said
exhaust line on the upstream side of said ori
fice, and means including a selector valve oper
y able at will to prevent the diversion of ñuid by
said main valve into `said exhaust line.
8. In a hydraulic system, the combination of a
substantially constant volume pump, an actuator
having an inlet and an outlet, means for direct
ing fluid from the pump to said actuator inlet,
a restricted oriñce interposed in the path of fluid
exhausting from the actuator outlet, means de
ñning a fluid diversion passage leading from the
discharge side of said pump, a movable valve
member interposed in said diversion passage and
spring biased into a position to restrict the same,
means for applying to said valve the pressure
across said orifice in a direction to oppose said
spring bias, and means for substantially simul
taneously interrupting not only the exhaust of
fluid from said actuator to said oriñce, but also
the application to said valve member of the pres
sure across said orifice and for applying to said
10
valve member the discharge pressure of said
pump.
9. In a hydraulic system, the combination with
pump to said actuator when the valve is in an oiï
application of a predetermined maximum pres
sure to said actuator for thereafter automatically
maintaining a substantially equalized pressure
across the actuator to prevent its further move
ment until the delivery of pressure ñuid from said
source is stopped.
`
12. In a hydraulic system, the combination of
a fluid delivery pump and a reversible actuator,
a conduit having branches, an exhaust line hav
ing branches, a main valve shiftable to at least
three selectively available positions therefor in
two or” which said pump is connected to said ac
tuator for movement of the latter in correspond
ing opposite directions and in the third of which
said positions said pump is disconnected from said
actuator and connected to a .branch of said ex
‘ haust line through a branch of said conduit,
means including a pressure operated valve for
maintaining the discharge pressure of said pump
at a predetermined value, means for utilizing
pressure in said conduit for rendering said pres
sure operated valve eiîective to maintain the pump
discharge pressure at said predetermined value
when sufûcient pressure is made available in said
conduit by shift of said main valve to said third
position, and a selector Valve located in said
branch of said exhaust line and connected when
said main valve is in said third position to a
branch of said conduit for optionally rendering
said pressure operated valve effective or ineiïec
tive by retaining pressure in or releasing pres
sure from said conduit.
`
CARROLL R. ALDEN.
REFERENCES CITED
The following references are of record in the
fue of this patent:
UNITED STATES PATENTS
Number
2,004,638
2,028,766
2,085,303
12,102,865
Name
Date
Smith ___________ __ June 11, 1935
Ernst ____________ __ Jan. 28, 1936
Ernst ____________ __ June 29, 1937
Vickers __________ __ Dec. 21, 1937
Документ
Категория
Без категории
Просмотров
0
Размер файла
1 011 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа