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Патент USA US2409350

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o@ 15;'1946. -
N. s. FOCHT
A2,409,349
HYDRAULIC- SHOCK ABSORBER
Filed Oct. 22, 1945A
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Patented Oct. 15, 1946
2,409,349
UNITED STATES PATENT 'OFFICE
2,409,349 4
HYDRAULIC SHOCKVABSORBER
Nevin S. Focht, Syracuse, N. Y.
Application October 22, 1945, Serial No. 623,762
6 Claims. (Cl. 1881-88)
2
movable elements such, for example, as the axle
This invention relates to shock absorbers, and
has particular reference to improvements in hy'
draulic shock absorbers of. the cylinder and pis
ton,- or strut type as disclosed, for example, in
my prior U. S. Patent No. 2,342,729 of February
29,. 1944, and in my copending application, Serial
No. 575,881.
A 'shock absorber of the type disclosed in ‘my
saidprior patent and application, includes a valve
and the chassis of a motor vehicle.
Concentric with and surrounding the cylinder
Ill in spaced relationship thereto is a tube I2,
while closing the ends of said cylinder and said
tube are heads designated generally as I3 and
i4, respectively. These heads may be of any suit
able construction and may be mounted in clos
ing relationship to the ends of said cylinder and
which is operable, under compression loads im
posed upon the shock absorber, to regulate flow
said tube in any suitable manner. For example,
of liquid from the cylinder to a reservoir and thus
I5 welded, threaded or otherwise suitably fas
tened to the related end of the tube I2, and a
separate valve seat element I6 superimposed upon
said main body element and having the related
end of the cylinder I0 seated thereon. Likewise, ‘
the head I3 may comprise a main body element
I'I welded, threaded or otherwise suitably fas
tened to the related end of the tube I2, and a
the head Ilmay comprise a main body element
regulate movement of'the piston in the cylinder,
thereby to cause the shock absorber smoothlyto
resist and absorb such loads.
.
The present invention relates more particularly
to improvements in such valves and has for its
object, generally speaking, to provide a compres
sion control valve which does not lock under peak
compression loads imposed upon the shock ab
separate plug element I8 interposed between said
main body element I'I and the related end of the
cylinder Ill. A piston rod I9 extends from the
piston I I through the head I3 and affords a means
of connecting `said piston with one of the pair of
sorber and which operates to cause the shock
absorber to resist and absorb all compression
loads in _a characteristic, smooth manner, regard
less of their severity and the speed of action of the
shock absorber.
y
c
,
25
,
` With the foregoing and` other objects in View,
which will become more fully apparent as the
nature of the invention is better understood, `the
same consists in a shock absorber compression
control valve embodying the novel featuresv of
relatively movable elements to be controlled. On
the other hand, a stem 20 extends from the head
I4 and affords a means of connecting the cylinder
I0 with the other of the relatively movable ele
ments to be controlled. The piston II divides the
cylinder I0 into recoil and compression pressure
chambers a and b, respectively, the former of
Iwhich is between said piston and the head I3
and the latter of which is between said piston and
the head I4, while the space between the cylin
appended claims.
'
i
35 der Inland the‘tube I2 constitutes a liquid reser
voir designated as c. As will be understood, the
In the accompanying drawing, wherein like
construction, combination and arrangement of
parts, and the novel modev of operatiorr‘as will
be hereinafter more fully described,` illustrated in
the accompanying drawing and defined in the
chambers a and b are ñlled with liquid and some
characters of ’ reference denote corresponding
parts in the different views:
Y
~
Fig. 1 is a central, longitudinal section throug
a shock absorber including a compression con
trol valve constructed and arranged in accord
additional liquid is contained in the reservoir c.
Between the main body element I5 and the
40 valve seat element IE of the head I4 is a space
ance with one practical embodiment of the in
2| Which‘i's in communication with the reservoir
c, while extending through said valve seat ele
vention.
ment is a central port 22 and a plurality of sur
`
'
‘
-
Fig. 2 is a central, longitudinalsection on an
rounding ports 23 which alford communication
enlarged scale through the compression control 45 between the chamber `b and said space 2I_ under
valve showing the same in its normal, closed po- ` `
the control of a metering pin 24 and a check
sition; and "
valve ring 25, respectively.
.
The port 22 is constricted intermediate its Vends
to afford a valve seat 26. The metering Din 24 ex
valve in an open position.
‘
Referring to the dra-wing in detail, it will be 50 tends through said port and, outwardly of said
observed that the present shock absorber is of the
valve seat, is formed with a valve portion 21 to
cylinder and piston or strut type 'shown and de
close inwardly‘against 'said seat and to open out
scribed in my aforesaid patent and application
wardly relative thereto. On the other hand, the
Fig. 3 is a View similar to Fig. 2 showing thev
and includes a cylinder I0 and a piston II for
check valve ring 25 is disposed inwardly of the
connection with any desired pair of relatively 55 valve seat element I6 for outward movement to
2,409,349
3
4
close and for inward movement to open the ports
piston` || moves toward the head I3, controlled
flow of liquid occurs through said piston from
23.
Between a suitable abutment on the inner'
end portion of the metering pin 24 and the check
valve ring 25 is interposed a spring 23 which tends
constantly to urge saio‘- check valve ring out
wardly to close the ports 23 and to urge said
metering pin inwardly to close the port 22.
the chamber a to the chamber b and thereby the
shock absorber is caused to resist and absorb the
force or shock which produced movement of the
piston | | toward the head | 3. At the same time,
the valve 25 is drawn open and enough liquid
is drawn from the reservoir c through the ports
In the stern 23 is a bore 29 in the inner end
portion of which the outer end portion of the
metering pin 24 is slidably disposed, while formed
23 into the chamber b to maintain said chamber
1:1
as an enlargement of the inner end portion of
said bore is a, well 3|) which opens at its in
ner end into the space 2| and in which is dis
posed a piston element 3| formed' as an annular
ilange projecting from the metering pin 24,
whereby a dash-pot is provided to resist outward
movement of said metering pin. BetweenY the
edge of the flange 3| and the wall defining the
side of the well 3€! is a small clearance space 32
for escape of liquid from said well to the space ~
ñlled with liquid, such drawing of liquid from the
reservoir c into the chamber b being due to the
fact that a lesser amount of liquid is displaced
from the chamber a.
Suflice it to say, too, that as the piston ||
. moves toward the head I2 as a result of a com
pression load or shock imposed upon the shock
absorber, liquid is displaced from the chamber b
and flows through said piston into the chamber
a; Since, however, because of the presence of
the piston rod I9 in the chamber a, said cham
2| to permit outward movement of the metering
pin 24 under the influence of liquid pressure ex
ber a cannot accommodate all of the liquid that
is displaced from the chamber b, the excess liquid
erted against its inner end.
'
is compelled to pass through either the port 22
In the metering pin 24 is an axial bore 33 and
or the bore 33 of the metering pin 24, or through
two lateral ports 3'4' and 35, the former of which 2. both said port and said bore, to the reservoir c;
is located inwardly of the valve seat 2B to alîord
Before movement of the piston || toward. the
constant communication between the chamber b
head |4 begins, the pressure in the chamber b is
and said bore 33 and the latter of which is located
zero. When, however, the piston || is moved
to alford communication between. said bore' 33
toward the head I4, pressure is generated in the
and the well 33 outwardly of the piston element 30 chamber b and this pressure, acting against the
3| under the control of a plunger pin 3B.
inner end of the metering pin 24, urges said pin
The bore 33 opens through the outer end' por
outwardly to open the port 22 and thusv permit
tion of the metering pin 24 andV the plunger pin
escape of liquid from said chamber b through
36 is slidable in the outer end portion of said
said port to the reservoir c to relieve the pres
bore. On said plunger pin is an annular flange
sure. In the case of small loads the pressure
31 and interposed between this flange and a plug
generated may not be suiiicient to impart any
38» threaded in the bore 29 of the stem 2E)> is a
outward movement to the plunger pin 36 but in
coil spring 39 which tends constantly to urge
the case of larger loads the pressure of the liquid
said plunger pin to its innermost position rela
against the inner end of the plunger pin 36
tive to the metering pin 24 as determined b-y seat 40 moves said plunger pin outwardly relative to the
ing of the flange 31 against the outer end of said
metering pin 24 and thereby uncovers the port
metering pin. The plunger 33 is of a length
35 with the result that escape of some of the
such that it covers the port 35- when it is iny its
liquid into the dash-pct well 3E! outwardly of the
innermost position relative tothe meteringl pin
24, but begins to uncover said port substantially
piston element 3| is permitted In this connec
immediately upon outward movement thereof
'relative to said metering pin. In thisfconnec
tion, the inner end portion of said pin 36 may
be tapered as shown to permit PI’OgïeSSi-Vely` i11
creasing flow of liquid from the bore 33 through .
the port 35 as said pin is moved outwardly rela'
tive to the metering pin 24. Alternatively, the
Yport; 35 may be of increasing area outwardlyv> to
obtain this same effect, regardless of whether the
‘inner end portion of the pin 33 is or is not ta
pered. In any event, movement of said- pin 36» to
its innermost position relative to the metering
pin 24A is effective to close the port 35 and thus
deny communication between the bore y33~and the
well 30, while outward movement of said pin 36»,
relative to said metering pin/ 24, is effective to
>uncover said port 35 and thus subject the outer
side of the piston elementv 3| to whatever liquid
pressure may be generated in thek chamber c by
movement of the piston. || toward the cylinder
head I4.
In accordance with the invention the piston | I
is provided with suitable means for controlled
flow of liquid therethrough between the cham
bers a and b. Such means may be of the type
illustrated and described in my aforesaid patent
Yory in my aforesaid application or of any other
suitable type. It is not shown because the-pres
ent invention is not concerned with the control
aiîorded4 thereby'.
Suiiîce it to say that' as the '
- tion, the strength of spring 23, the area of the
space 32 for escape of liquid from the dash-pot
well 30, and the strength of the spring 3-9, are
such that if the load imposed upon the shock ab
sorber and the pressure generated are normal,
the plunger pin 36 is moved only a small amount
outwardly relative to the metering pin 24 and
there is admitted to the well 33 only such a
small volume of liquid at such low velocity that'it
may readily escape from said well through the
space 32 and therefore will not act seriouslyV in a
differential manner against the outer side of the
piston element 3| to resist outward movement
of the metering pin 24, while- said metering pin
will be moved outwardly an amount to permit
escape of just the required amount of liquid'to
cause the shock absorber' smoothly and evenly to
absorb the load or shock imposed thereon.
If the load or shock imposed upon the shock
absorber should be abnormal', the shock absorber
initially will function as'just described. However,
with rise in the pressure of the liquid as the load
or shock increases, the plunger pin 36 will be
moved farther outward relative to the. metering
pin 24 and` permit increased flow of liquid into
the dash-pot well 3U. Thisv increased flow will
_cause a choking of the clearance space 32y anda
rise in the pressure acting inwardly upon. the
metering pin 24 relative to the pressure acting
outwardly thereagainst with the result that said
metering pin will be urged inwardly and will de..
'ca-iconic
6
crease the» effective area of the‘port `22. Hence,
thereinßa portaifording communication between
there will occur a progressive rise inthe resistance
of the shock absorber to the abnormal load .im
posed thereon and such load will be smoothly and
evenly absorbed as in the case of a normal load
sa'id end o'f‘said cylinder and said reservoir, a
metering pin extending through said port and in'
wardly movable to close and` outwardly movable
to open the same, yieldable means tending con
stantly to urge said pin inwardly to a port-closing
lor shock. In other words, the present construc
position-the inner end of said pin being exposed
within the said end of said cylinder for subjection
tion consistently aiîords‘the desired “bottoming”
control desired in an ideally, resiliently suspended
vehicle body, gun carriage or the like, for even if
an exceptionally seven; suddenly applied shock
should result in complete closure of the port 22
by inward movement of the metering pin 24,
liquid still would be able to escape via the port 35
and no locking or solid action of the shock ab
sorber could result. Consequently, `there is elim
inated any necessity of a pop-olf valve such, for
example, as the pop-off valves of my prior patent
and application. Moreover, since the dash-pot
well 3l] is charged by the very action which is to
10
tolliquid pressure to urge said pin outwardly and
thus "opensaid port, said pin having a bore ex
tending longitudinally thereof, said bore opening
through the outer end of said pin and being in
constant communication with said end of said cyl
inder, said head having a well and said pin hav
15 a, piston portion disposed in said well to provide
a-,dash-pot to resist outward movement of said
pin, said `pin having a side opening affording
communication between said bore and said well
outwardly of said piston portion, a plunger pin
be controlled, there never can be a loss of in 20 slidable in said bore, and yieldable means tend
stantaneous control regardless of speed of action.
ing constantly to urge said plunger pin inwardly
lAs increased compression loads imposed upon
to a_ position closing the side opening in said
the shock absorber produce increased velocities
metering pin, said plunger pin being movable
in the shock absorber liquid,\this might mean,
outwardly by pressure of liquid against its inner
in the'case of abnormal compression loads im 25 end to open -said side opening and thus admit
posed upon the shock absorber, such rapid out
liquid to said well to urge said metering pin in
ward movement of the plunger pin 36 and such
consequent rapid flow of liquid into the well 30,
`.2.¿In a hydraulic shock absorbena cylinder,
with such consequent inward movement of the
a piston reciprocable therein, a liquid reservoir,
metering ‘pin 24, as to cause the increase in re 30 a‘ head `closing one end of said cylinder and hav
ing therein a port affording communication be
sistance to compression of the shock absorber to
tweenfsaid end of said cylinder and said reservoir,
exceed the desired value, were it not for the fact
a` metering pin extending through said portand
`that the plunger pin 36 is itself dash potted to
inwardly movable to close and outwardly mov
cause the by-pass flow into the well 30 to be more
ableto open the same, yieldable means tending
-orI less cfa constant volume value.
constantly to urge said pin inwardly to a port
In this connection it is pointed out- that the
closing position, the inner end of said pin being>
`flange' 31 ofthe plunger pin 36 is of suitably
>exposed within the said end of said cylinder lfor
lesser diameter'than the bore 29 and, by reason
subjection to liquid pressure to urge said pin
of operating in said bore, serves to provide a dash
pot to control outward movement of said plunger 40 outwardly andthus open said port, said head
having a well and said pin having a piston por‘
‘pi`n.~ Thus,` regardless of the pressure and the
tion disposed in said well to provide a dash-pot
velocity ofthe liquid, outward movement of said
-to "resist outward movement of said pin, and
plunger pin is retarded to as to avoid‘such` rapid
mëansfincludinga yieldably closed valve open
inward movement of the metering pin 24 as to
wardly..„
'
" i
'
'
cause the compression resistance of the shock ‘W ' ‘able‘by the pressure of the liquid to admit a por
tion of the liquid to said well outwardly’ of the
absorber to exceed the desired value. It is further
piston portion of said pin to urge said pin in
pointed out that there is a suitable clearance
wardly.
space 24' between the outer end portion of the
3. In a hydraulic shock absorber, a cylinder,v
metering pin 24 and the wall defining the bore
29 for flow of liquid between said bore, outwardly 50 a piston reciprocable therein, a liquid reservoir,
a head closing'one end of said cylinder and hav
of the outer end of said metering pin, and the
ing therein a port'aifording communication be
well 30, whereby liquid displaced by the dash pot
tween said end of said cylinder and said reser
flange or piston 3l ofthe plunger pin 36 during
voir, a metering pin extending through said port
outward movement of said plunger pin, may enter
the well 30 and be metered therefrom through the 55 and inwardly movable to close and outwardly
movable to open the same, yieldable means tend
clearance space 32.
ing constantly to urge said pin inwardly to a
The plug 38 is adjustable in the bore 29 to vary
port-closing position, the inner end of said pin
the effective strength of the spring 39 and thus
being exposed within the said end of said cylin
adapt the shock absorber for most efñcient use
60 der for subjection to liquid pressure to urge said
in different installations. '
pin outwardly and thus open said port, said head
From the foregoing description considered in
having a well and said pin having a piston por
connection with the accompanying drawing it
tion Ydisposed in said well to provide a dash-pot
is believed that the features comprising the in..
to resist outward movement of said pin, and
vention will be fully understoood and their advan
tages appreciated.v It is desired to point out, 65 means affording communication through said pin
between said end of said cylinder and said Well
however, that while only a single specific struc
outwardly of the piston portion of said` pin, said
tural embodiment of the invention has been il
means including a yieldably closed valve open
lustrated and described, the same readily is ca
able bythe pressure of the liquid to admit a por
pable of specifically different structural embodi
ments within its spirit and scope as defined in the 70 tion of the liquid to said well to urge said pin
inwardly.
appended claims.
I claim:
~
.
1. In a hydraulic shock absorber, a cylinder, a
piston reciprocable therein, a liquid reservoir, a
head closing one end of said cylinder and having
4. In a hydraulic shock absorber, a cylinder, a
piston reciprocable therein, a liquid reservoir, a
Vhead closing one end of said cylinder and having
therein a port affording communication between
¿2,409,349
7
8
said 'end of said cylinder and> said reservoir. a
pinV to urge said pin inwardly, and dash-pot
metering pin extending throughf said port and
inwardly movable-to close and outwardly movable
means' controlling opening movement of said
valve.
6. In a hydraulic shock absorber, a cylinder, a
pistonl reciprocable therein, a liquid reservoir, a
Vhead closing one end of said cylinder and having
therein a port affording communication between
said end of’ said' cylinder and said reservoir, a
to- open the same, yieldable means- tending con
stantly to urge said pin inwardly to a port-closing
position, the inner end of said pin being» exposed
within the said end of said cylinder for subjec
tion to liquid pressure to urge said pin outwardly
and thus open said port, sa-id pin having> a bore
metering pin extending through said port and
extending longitudinally thereof, said bore open 10 inwardly movable to close and outwardly movable
ing through the outer end of said pin and being
to open the same, yieldable means tending con
in constant communication with said end of said
stantly to urge said pin inwardly to a port-closing
cylinder, said head havingv a well and said pin
position, the inner end of said pin being exposed
having a piston portion disposed in said well to
within the said end of said cylinder for sub
provide a dash-pot to resist outward movement
jection to liquid pressure to urge said pin out
of said. pin, sai-d pin having a side opening afford
wardly and thus open said port, said pin having
ing communication between said bore and said
a bore extending longitudinally thereof', said bore
well outwardly of said piston portion, a plunger
opening through the outer end of said pin and
pin slidable in said bore,> yieldable means tending
being in constant communication with said end
constantly to urge said plunger pin inwardly to 20 of -said cylinder,v said head having a well and said
a position closing the side opening in said meter
pin having a piston portion disposed in said well
ing pin, said plunger pin being movable outward
tofprovide a dash-pot to resist outward move
ly by pressure of liquid against its inner end to
ment ofvsaid pin, said pin having a side opening
open> said side opening and thus admit liquid to
affording communication between said bore and
said well> to urge said metering pin inwardly, and 25 said well outwardly of said well outwardly of said
dash-pot means controlling- outward movement
piston‘portion, a plunger pin slidable in said bore,
of said plunger pin.
yieldable means tending constantly to urge said
` 5. In a hydraulic shock absorber, a cylinder, a
plunger pin inwardly to a position closing the
piston reciprocable therein, a'liquid reservoir, a
saidA opening in said metering pin, said plunger
head closing one end of said cylinder and having 30 pin being movable outwardly by pressure of liq
therein a port aiTording communication between
4saicl- end of said cylinder and said reservoir, a
uid against its inner end to open said side open
ing and thus admit liquid to said well to urge
metering pin extending through said port and
said metering pin inwardly, the piston portion
inwardly movable to close and outwardly mov
of said metering pin having clearance from the
able to open the same, yieldable means tending 35 wall deñning the side of said well for metered
constantly to urge said pin inwardly to a port
elosing position, the inner end of said pin being
exposed within the said end> of said cylinder for
subjecting to liquid pressure to urge said pin out
wardly and thus open said port, said head having 40
a well- and said pin having a piston portion dis
posed in said well to provide a dash-pot to resist
outward movement of said pin, means including
a yieldably closed valve openable by the pressure
ofthe liquid to admit a portion oi?v the liquid to 45
said well outwardly of the pistonl portion of said
escape from said well of liquid displaced there
fromV by outward movement of said piston por
tion, said head having a bore and said plunger
pin having a piston portion operating in said
bore to afford a dash-pot to control outward
movement of said plunger pin, and means for
flow into said well of liquid displaced from said
_ bore by said. plunger pin piston portion.
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