Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE INVENTION
This invention relates generally to energy absorbers and,
in particular, to an adjustable hydraulic shock absorber which
is capable of being adjusted to absorb shock loads of varying
amounts.
BACKGROUND OF THE INVENTION
Energy absorbers have often been customized or built in
accordance with the requirements of the particular load condi-
tions under which they were to perform. This is highly undesir-
able since building a shock absorber for each type of job iscostly and time consuming. Further, customized shock absorbers
are necessarily of many different sizes and there is generally
no standardization among the indiviudal components thereof,
thereby making maintenance expensive and difficult.
To overcome the above disadvantage, several energy absorbers
have been commercially manufactured which permit the energy
absorbing capability thereof to be adjusted in accordance with
the expected load conditions, thereby permitting the shock
absorber to be utilized in many different loading and environ-
mental conditions. While many of these adjustable energyabsorbers have been adaptable to a wide range of load conditions,
nevertheless these energy absorbers have not been as widely
utilized as the area of need for same might indicate since they
have been relatively costly. Specifically, most known adjustable
energy absorbers have utilized a complex adjustment structure
which is both expensive to manufacture and difficult to use.
More specifically, these known shock absorbers have required
an excessive amount of precise, and hence costly machining.
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2;~
Also, many of the known adjustable shock absorbers use
concentric, inner and outer control sleeves which are relatively
movable for controlling flow between two chambers. However,
these sleeves must be machined with extremely precise tolerances
and/or machined as a matched pair in order to permit proper fit
and operation. This thus prevents random assembly of the parts,
and hence substantially increases the cost of assembly.
Accordingly, it is an object of this invention to provide
an improved energy absorber, particularly a hydraulic shock
absorber, which overcomes the above-mentioned disadvantages.
It is also an object of this invention to provide:
1. An improved energy absorber, as aforesaid, capable of
being adjusted to absorb shock loads of varying amounts.
2. An energy absorber, as aforesaid, which is easily and
precisely ad~ustable to vary the energy absorption characteristic
thereof.
3. An energy absorber, as aforesaid, which permits the
energy absorption characteristic to be precisely adjusted to a
level compatible with the external load imposed thereon.
4. An energy absorber, as aforesiad, which is capable of
absorbing progressively increasing amounts of energy so as to
result in a substantially uniform, that is a substantially
linear, stopping of a movable load.
5. An energy absorber, as aforesaid, which utilizes a
control structure containing inner and outer concentric sleeves
with one sleeve having an axially extending row of control
openings therethrough, which sleeves have opposed conical sur-
faces thereon and are relatively axially movable to form a
variable width flow control passage therebetween and thereby
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~05~ 9
control the flow of fluid between two compartments so as to
adjust the energy absorption capability of the shock absorber.
6. An energy absorber, as aforesaid, which permits the
inner and outer control sleeves to be machined with normal
tolerances while still permitting random selection of parts
during assembly.
7. An energy absorber, as aforesaid, which is simple and
compact in construction, economical to manufacture, efficient
in operation, and simple to adjust.
Other objects and purposes of this lnvention will be ap-
parent to persons acquainted with apparatuses of this type upon
reading the following specification and inspecting the accompany-
ing drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a central sectional view of an adjustable
energy absorber according to the present invention.
Figure 2 is a fragmentary sectional view taken along the
line II-II in Figure 1.
Figure 3 is a fragmentary sectional view of thepiston
assembly and showing the position thereof when the ram is being
pushed into the shock absorber.
Figure 4 is a view similar to Figure 3 but showing the
piston assembly when the ram is being moved outwardly of the
shock absorber, in which position the piston functio~s as an
opened one-way check valve.
Figure 5 is a central sectional view of a further embodiment
according to the present invention.
Figure 6 is an enlarged, fragmentary sectional view taken
along the line VI-VI in Figure 5.
z~
Figure 7 is a view similar to Figure 6 but illustrating
the inner and outer control sleeves in an open or spaced con-
dition.
Figure 8 is a fragmentary sectional view taken substan-
tially along the line VIII-VIII in Figure 7.
Figure 9 is a central sectional view showing a preferred
embodiment of an adjustable energy absorber.
Figure 10 is a fragmentary sectional view along line
X-X in Figure 9.
Figure 11 is a view similar to Figure 10 but showing the
control sleeves in a spaced or open condition.
Figure 12 is a fragmentary sectional view taken along
line XII-XII in Figure 11.
Figure 13 is an enlarged, fragmentary, central sectional
view of the piston end of the ram.
Figure 14 is an enlarged, fragmentary sectional view of
a modified structure.
SUMMARY OF THE INVENTION
The objects and purposes of the present invention are
met by providing an energy absorber having a housing which
contains an adjustable sleeve means therein, which sleeve
means divides the housing into a pair of fluid chambers. A
ram extends from the housing and has a piston slidably received
within one of the fluid chambers. The adjustable sleeve
means includes inner and outer concentric control sleeves
which can be selectively axially displaced one relative to
the other. One of the sleeves has an axially extending row
of control openings extending therethrough. The con-
centric control sleeves have opposed conical surfaces which
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can be disposed in substantial engagement with one another to
thereby close off the control openings and prevent flow of fluid
between the fluid chambers. By relatively axially moving the
concentric control sleeves away from this position, so that the
opposed conical surfaces are slightly spaced from one another,
there is formed a flow control passage between the concentric
control sleeves which, in conjunction with the control openings,
permits the controlled flow of fluid between the chambers. Im-
position of an external force on the ram caused the piston to
move axially through the one chamber to force fluid therefrom
through the control openings and the control passage into the
other chamber, while permitting the fluid to absorb some of the
ram energy due to the restricted fluid flow through the control
openings and the control passage. The piston progressively
closes off the control openings as it moves axially into said
one chamber to thereby also control the energy absorption
characteristic of the shock absorber. The quantity of energy
absorbed by the shock absorber can be selectively adjusted by
causing relative axial displacement between the control sleeves
0 to thereby vary the size of the control passage.
DETAILED DESCRIPTION
R~ferring to Figures 1-4, there is illustrated an energy
absorber 10, specifically a hydraulic shock absorber, which in
cludes a housing 11 having a ram assembly 12 slidably positioned
in and extending therefrom. A flow control sleeve assembly 13
is positioned within the housing for controlling relative move-
ment between the housing 11 and the ram assembly 12 due to the
imposition of an external load on the shock absorber. The flow
control sleeve rneans 13 is adjustable, as explained hereinafter,
to permit the quantity of energy absorbed by the shock absorber
to be selectively varied.
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The housing 11 includes a hollow cylindrical sleeve 16
fixedly connected between a pair of end members 17 and 18.
The flow control sleeve means 13 includes an inner cylin-
drical control sleeve 21 positioned within the housing and ex-
tending substantially the full axial length thereof. The
sleeve 21 is rotatably received at one end within a bore 22
formed within and extending through the end member 17. The
other end of sleeve 21 has a stub shaft 23 fixedly connected
thereto, which stub shaft 23 closes off the end of a chamber 27
defined within the control sleeve 21 and projects through an
opening 24 formed in the end member 18, whereby stub shaft 23
is rotatably supported on the end member. A retainer ring 26
coacts between stub shaft 23 and end member 18, whereby the
stub shaft 23 maintains the sleeve 21 axially fixed with respect
to the housing 11.
The ram assembly 12 includes a cup-shap~d piston 28 which
is snugly and slidably received within the chamber 27, which
piston 28 is connected to an elongated piston rod 29 by a
threaded bolt 31. The piston rod 29 is slidably and sealingly
support~d by a bushing 39 which is fixedly positioned within the
end of sleeve 21.
The bolt 31 and the cup-shaped piston 28 have suitable
clearance passages therein for defining a one-way check valve
structure to assist in channelling fluid into the chamber 27
when the ram assembly is being extended, that is, being moved
leftwardly in Figure 1.
Referring to Figures 3 and 4, the bolt 31 has an inter-
mediate cylindrical shank portion 32 which extends through a
hole 33 formed in the end wall of the piston 28, which hole is
of larger diameter than the shank portion so as to define an
annular clearance passage 34 therebetween. The shank portion
32 has a length which is greater than the thickness of the
bottom wall of the piston 28 so that the piston 28 can move
axially relative to the piston rod 29 between the two positions
illustrated in Figures 3 and 4. When the piston 28 is in its
outermost position as illustrated in Figure 4, there is thus
defined a small clearance space or chamber 36 between the piston
and the adjacent end of the piston rod 29, which space 36 com-
municates with a pair of grooves 37 which are formed in the
piston and extend axially through the free end thereof. The
grooves 37 at their rearward (leftward) ends communicate with a
chamber 38 which is formed between the piston 28 and the
bushing 39 when the ram assembly is displaced inwardly (right-
wardly in Figure 1) from its fully extended position. ~he piston
28 also has grooves 35 on the front face thereof which provide
communication between the passage 34 and the chamber 27.
As illustrated in Figure 3, when the ram assembly is being
contracted (moved rightwardly in Figure 1), the piston 28 is
moved into abutting engagement with the free end of the piston
rod 29. The intermediate chamber 36 between the piston and the
piston rod i5 thus closed off so that passage 34 is isolated from
the grooves 37.
The ram assembly 12 has the piston rod 29 thereof projecting
outwardly from the housing, which piston rod is provided with an
enlarged head 41 fixedly mounted thereon. A compression spring
42 surrounds the piston rod 29 and coacts between the head 41 and
a retainer ring 43 for resiliently urging the ram assembly 12 into
its outermost or fully extended positlon as illustrated in Figure
1. In this full~ extended position, the piston 28 abuts against
the bushing 39, and the piston 28 abuts against the head of the
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bolt 31. While the spring 42 has been illustrated as disposed
externally of the housingr it will be appreciated that the
spring could be positioned within thehousing if desired.
The flow control sleeve assembly 13 also includes an outer
cylindrical control sleeve 46 disposed concentric with and in
surrounding relationship to the inner control sleeve 21. The
outer sleeve 46 has one end thersof joined to the housing 11,
specifically the end member 18, by means of a threaded con-
nection 47 which normally maintains the outer control sleeve
46 stationary relative to the housing during normal operation
of the shock absorber. However, threaded connection 47 permits
the outer sleeve 46 to be rotated relative to the housing when
adjustment of the controlsleeve assembly 13 is desired.
The outer control sleeve 46 is, in the illustrated embodi-
ment, nonrotatably connected to the inner control sleeve 21 by
a pair of pins 48 which as fixed to sleeve 46 and project in-
wardly thereform. The pins 48 extend into axially elongated slots
49 formed on diametrically opposite sides of the inner sleeve 21.
This pin-and-slot connection between sleeves 21 and 46 prevents
relative rotation therebetween but permits the outer sleeve 46
to be axially displaced relative to the inner sleeve 21 when the
complete sleeve assembly 13 is rotated relative to the housing 11.
The control sleeves have opposed conical surfaces formed
thereon for controlling the energy absorption characteristic of
the shock absorber, and for this purpose the outer control sleeve
46 has an inner conical surface 52 thereon which is disposed op-
posite and is adapted to be engaged with an outer conical sur-
face 51 as formed on the inner control sleeve 21. The inner and
outer conical surfaces 51 and 52, respectively, are of an identi-
cal taper, which taper preferably extends at a small angle.
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relative to the longitudinally extending axis A of the shockabsorber. In the illustrated embodiment, the taper of the
conical surfaces is normally within the range of between 1 and
5, although the present lnvention also contemplates the use of
a larger angle oE taper. The conical surfaces 51 and 52 are
maintained in engagement with one another when the sleeve as-
sembly 13 is in its fully closed position, in which position the
outer sleeve 46 is in its leftwardmost position whereupon the
rightward end of sleeve 46 is thus spaced from the end wall of
end member 18. However, Figure 1 illustrates the sleeve 46 in
its rightwardmost position whereupon the sleeve assembly 13 is
in its fully opened condition so that a maximum annular flow
pass~ge 53 is formed between the conical surfaces 51 and 52.
This annular flow control passage 53, as formed between the coni-
cal surfaces of the control sleeves, communicates with the chamber
27 through an axially extending row of openings 54 as formed in
the sidewall of the inner control sleeve 21. The large diameter
end of the flow passage 53, that is the leftward end in Figure 1,
communicates with a chamber 56 which is formed within the housing
11 in surrounding relationship tothe sleeve assembly 13.
The chamber 56 is in continuous communication with the
chamber 38, and for this purpose the end member 17 is provided
with a pair of passages or grooves 58 formed therein, which
grooves have their rearward ends in communication with openings
59 formed in sleeve 21, which openings communicate with chamber
38.
OPERATIO~
In an operational position, the energy absorber 10 is
normally maintained with its ram assembly 12 in an extended
position as illustrated in Figure 1 due to the urging of spring
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42. The absorber 10 is filled with fluid, such as hydraulic
oil, so that the fluid completely fills at least the chamber 27.
When so prepared, the energy absorber 10 is in condition for
engagement by an apparatus from which energy is to be absorbed,
which apparatus will move the piston rod inwardly into the housing
for decelerating the apparatus or absorbing shock blows therefrom.
When an external load or shock blow is imposed on the ram
assembly 12, this causes the piston rod 29 to move inwardly into
the housing, which in turn causes inward (rightward) movement of
the piston 28. During this rightward movement of the piston,
the piston is maintained in the position illustrated in Figure 3
so that the one-way check valve structure formed therein is
closed. The inward movement of piston 28 causes pressurization
of the fluid contained within the inner chamber 27, which fluid
is forced through the openings 54 and through flow passage 53
into the outer chamber 56. As the piston 28 moves axially toward
therightward end of the housing, it sequentially closes off the
openings 54, which in turn progressively restricts the further
flow of fluid from the chamber 27 into the chamber 56. This
thus causes the piston 28 to progressively decelerate so that as
the piston approaches the inner end of the chamber 27 (rightward
end in Figure 1), the external shock load imposed on the shock
absorber 10 will be substantially dissipated.
During the inward movement of the ram assembly, as explained
above, the chamber 38 as formed behin~ the piston 28 progressively
enlarges. This chamber 38 fills with fluid due to its communi-
cation with chamber 56 through the passages S8 and openings 59.
When the inward movement of the ram assembly has been
stopped and when the external load has been removed from the
head portion 41, the ram assembly is returned to its original
la)~ 3
extended position due to the urging of the spring 42. During
this return movement of the ram assembly, the fluid in chamber
38 causes the piston 28 to be moved rightwardly relative to the
piston rod 29 so as to assume the position illustrated in Figure
4, in which position the intermediate chamber 36 is opened so as
to permit communication between the passages 34 and 37. This
one-way check valve structure as formed by the passages 34-37
thus facilitates the flow of fluid from chamber 38 into chamber
27 as the ram assembly is being returned to its fully extended
position. When the ram is fully extended~ the openings 62 ensure
that the chamber 21 is completely filled with fluid.
As is understood, the deceleration rate of the ram assembly
12 is determined by the quantity and velocity of the fluid
escaping from the inner chamber 27 through the openings 54 and
passage 53 into the outer chamber 56. To adjust the deceleration
rate of the ram assembly 12, and thereby vary the energy dis-
sipating characteristic of the shock absorber 10, the complete
sleeve assembly 13 is rotated relativa to the housing 11, which
rotation can be accomplished by manually turning the hand wheel
61, which hand wheel could also be mounted on the stub shaft 23
if desired. This rotation of the sleeve assembly 13 causes the
outer control sleeve 46 to be axially displaced relative to the
inner sleeve 21 due to the threaded connection 47. Since the
sleeve assembly can be rotated through an arcuate distance equal
to severai complete revolutions, this thus permits a very fineand
precise adjustment in terms of the axial displacement of the outer
sleeve 46 relative to the inner sleeve 21, which axial adjustme~t
in turn varies the radial spacing between the conical surfaces 51
and 52 and hence varies the cross-sectional area of the annular
flow passage 53.
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MODIFICATION
Figures 5-8 illustrate therein a preferred embodiment of
the invention which incorporates therein many of the structural
and operational features possessed by the shock absorber 10 of
Figures 1-4. Accordingly, the parts of the shock absorber il-
lustrated in Figures 5~8 have been designated by the same
reference numerals used to designate corresponding parts of the
shock absorber illustrated in Figures 1-4 except that the
reference numerals have been increased by 100.
In the shock absorber 110, the inner control sleeve 121
extends between and is supported on the end members 117 and 118,
and the outer control sleeve 146 is disposed concentric with
and in surrounding relationship to the inner sleeve 121. Outer
sleeve 146 has an inner conical surface 152 thereon which is
disposed opposite the outer conical surface 151 formed on the
inner sleeve 121, which conical surfaces are adapted to be
slightly spaced apart so as to provide a flow control passage
153 therebetween.
In this embodiment, the inner control sleeve 121 is pro-
vided with a pair of elongated slots 171 (Figures 6 and 7) formed
in the outer conical surface 151, which slots 171 extend axially
of the sleeve 121 throughout the length of the outer sleeve 146
and terminate in openings 171A (Figure 8) which communicate with
the outer chamber 156. The slots 171 are disposed closely
adjacent and on opposite sides of the axially extending row of
openings 154, whereby the slots result in the formation of narrow
circumferentially extending lands 172 between the row of openings
154 and the adjacent slots 171. These lands 172 are spaced from
the opposed inner conical surfac~ 152 and thus define narrow con-
trol passages 173 therebetween for controlling the fluid flow
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from the openings 154 into the slots 171.
The slots 171 are formed in the sleeve 121, as by a milling
cutter, such that the bottom wall of each slot extends substan-
tially parallel to the axis A. This results in the cross-
sectional area of each slot 171 progressively increasing as
the slot extends from the inner or rightward end thereof to the
outer or leftward end thereof as illustrated in Figure 8. The
slot 171 is thus effectively of zero cross-sectional area at the
rightward end of the control sleeve 146, whereas the slot 171
progressively increases in cross-sectional area so as to have a
maximum cross-sectional area adjacent the leftward end of the
control sleeve 146.
While Figures 6 and 7 illustrate the use of two slots 171,
with one being positioned on each side of the row of openings
154, it will be appreciated that the shock absorber 110 could
be provided with only a single slot 171 if desired.
The outer control sleeve 146 is axially adjustable relative
to the inner control sleeve 121 so as to vary the radlal width
or dimension or the passages 153 and 173. For this purpose,
shock absorber 110 is provided with an adjustment means 114
which includes a knob or handle 176 fixedly secured to the outer
end of a control shaft 177, which control shaft is in turn
rotatably and sealingly supported on a housing hub 178 so that
the control shaft 177 is rotatable about an axis which extends
substantially perpendicular to the axis A. Control shaft 177
has a cam or eccentric 179 fixedly secured to the inner end
thereof, which eccentric 179 is engaged with an opening or slot
181 formed in the outer control sleeve 146. The eccentric 179
is preferably of circular cross-section and has the axis thereof
eccentrically displaced from the axis of the shaft 177, whereby
eccentric 179 functions like a crankpin. The slot 181 has a
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width, as measured in the axial direction of the control sleeve,
which substantially corresponds to the diameter of the eccen-
tric 179 so that the eccentric is snugly accommodated therein.
However, the length of the slot 181, as measured circumferenti-
ally of the control sleeve, is preferably greater than the
diameter of the eccentric to thereby compensate for the sideward
displacement of the eccentric during rotation of the control
shaft 177.
The control shaft 177 is rotatable through a maximum angle
of 180, and preferably less, so as to cause a corresponding
rotation of the eccentric 179, which in turn causes axial dis-
placement of control sleeve 146 between two endmost positions~
When the adjustment mechanism is in the position illustrated in
Figure 5, in which position the eccentric is in its leftward
end position, the outer control sleeve 146 effectively abuts
against a stop 182 as formed on the inner control sleeve 121,
thereby resulting in a minimum clearance between the conical
surfaces 151 and 152 so that the openings 154 are effectively
closed. The presence of the stop 182, however, prevents the two
conical surfaces 151 and 152 from being lockingly wedged to-
gether. When the controlknob 176 and eccentric 179 are rotated
away from the position illustrated in Figure 5, then the outer
control sleeve 146 is moved axially rightwardly so that the
spacing 153 between the conical surfaces 151 and 152 is in-
creased, with the maximum spacing 153 existing when the end of
sleeve 146 abuts against the stop surface 188. Rotation of
knob 176 thus permits the spacing 153 between the conical sur-
faces 151 and 152 to be selectively varied and adjusted so as to
provide for the desired restricted flow of fluid from the inner
chamber 127 into the outer chamber 156 when the ram assembly 112
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is moved inwardly into the housing 111.
The shock absorber can be suitably locked in its selected
position by means of a set screw 183 which locks the knob 176
to the hub 178 and thereby fixedly maintains the positional
relationship between the control sleeves 121 and 146.
The housing has a port 186 associated therewith for per-
mitting filling of the shock absorber with fluid, such as
hydraulic oil. After filling, the port 186 is normally closed
by means of a conventional plug.
When an external load or shock force is imposed on the ram
assembly 112, the piston 128 moves inwardly (rightwardly) into
the compartment 127, thereby forcing fluid outwardly through the
openings 154. The fluid then flows over the land 172 into the
slots 171, since this is the path of least flow resistance. The
fluid then flows along the slots 171 and discharges through the
ends 171A thereof into the outer chamber 156. The restriction
imposed on the fluid flow by the openings 154 and control pas-
sages 173 thus absorbs the energy of the apparatus which is
impacting against the ram assembly, and accordingly caused a
deceleration of the ram assembly.
As the ram assembly moves further into the compartment 127,
the piston 128 progressively closes off the openings 154 so that
the flow of fluid from chamber 127 into chamber 156 is further
progressively restricted, thereby causing a progressive
deceleration of the ram assembly as it approaches the rightward
end of the shock absorber. This progressive closing of the
openings 154, coupled with the flow passage 173 formed between
the openings 154 and the slots 171, thus causes a very uniform
deceleration and stopping of the ram assembly. Further, since
the grooves 171 are of progressively increasing cross-sectional
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area, they readily accommodate the variable flow therethrough
depending upon the number of openings 154 which are uncovered.
For example, when the pi.ston 128 is adjacent the leftward end
of the shock absorber, a large number of openings 154 are un-
covered so that fluid will flow through the openings 154 into
the slots 171 along substantially the complete length thereof,
whereupon a large quantity of fluid will flow into the slots
for passage into the outer chamber 156. This larger quantity
of fluid is permitted since the cross-sectional area of the
slots 171 progressively increases towards the discharge end
of theslots in correspondence with the progressive spac-
ing of the openings axially along the inner control sleeve.
On the other hand, when the piston 128 is more closely adja-
cent the rightward end of the shock absorber, only a few open-
ings 154 are uncovered so that a substantially smaller quan-
tity of fluid flows into the slots 171 for discharge into the
outer chamber 176.
It will be appreciated that the adjustment mechanism 114
could be replaced with other suitable mechanisms capable of
causing the desired axial movement between the sleeves 121
and 146.
Figure 9 illustrates an energy absorber 210, specifically
a hydraulic shoc~ absorber, which includes a housing 211
having a ram assembly 212 slidably positioned in and extend-
ingtherefrom. A flow control sleeve assembly 213 is posi-
tioned within the housing for controlling relative movement
between the ram assembly 212 and the housing 211 due to
imposition of an external load on the shock absorber. The
flow control sleeve assembly 213 is adjustable, as explained
-17-
hereinafter, to permit the quantity of energy absorbed to
be selectively varied.
The housing 211 includes a hollow cylindrical sleeve
216 fixedly connected between a pair of end members 217
and 218~
The flow control sleeve assembly 213 includes an inner
cylindrical control sleeve 219 positioned within the housing
and extending substantially the full axial length thereof.
The sleeve 219 is fixed with respect to the housing and has
the rightward end thereof pressed onto a member 221 which
abuts against the end member 217~ The leftward end of
sleeve 219 is snugly seated on an annular projection 222
which extends inwardly from a bearing sleeve 222 which is
fixedly and sealingly mounted on the other end member 218.
A conical wall 223 is formed on the inner edge of the left-
ward end of sleeve 219, and a conventional elastomeric O-
ring 224 is clampingly engaged between the wall 223 and the
corner defined on the end member 218 to create a sealed re-
lationship therebetween. Thisstructure overcomes any pro-
blem caused during the assembly of the shock absorber dueto the accumulation of axial tolerances on the individual
parts, whereby the individual parts can be manufactured
with less stringent tolerances and a-t the same time permit
a more efficient assembly of the shock absorber.
As an alternative, the leftward end of sleeve 219 can
have an annular recess 223' formed therein, as shown in
Figure 14, so as to accommodate the O-ring 224'.
The ram assembly 212 has a substantially cylindrical
piston 226 on the inner end thereof, which piston is dis-
posed within a chamber 227 defined within the inner control
-18-
sleeve 219 and is slidably guided for axial movement there-
along. The piston 226 is fixedly secured on the inner
end of a piston rod 228. The piston rod has a reduced dia-
meter portion for accommodating the piston thereon, which
piston abuts against a shoulder 229 formed on the rod 228.
The piston 226 and piston rod 228 have aligned holes 231A
and 231B (Figure 13) extending diametrically thereacross,
which holes receive therein an elongated axially split
spring pin 232. The pin 232 expands circumferentially to
be snugly accommodated within the holes 231A-231B so as
to fixedly interconnect the piston and the piston rod.
The piston 226 has an annular groove 233 extending
therearound, which groove communicates with the holes 231.
A conventional annular split piston ring 234 may, if neces~
sary, be disposed in the groove 233 to create a slidable
sealed engagement with the inner wall of the sleeve 21g.
Piston ring 234 also retains the spring pin 232 within the
holes 231.
A one-way check valve assembly 236 is associated with
the inner end of the ram assembly, particularly the piston
226. This check valve assembly 236, as shown in Figures 9
and 13, includes a first passage formed as a large diametex
bore 237 extending coaxially inwardly from the inner free
end of the piston rod 228. This bore 237 in turn communicates
with and is coaxially aligned with a further passage formed
as a small diameter bore 238. A further passage 239 extends
radially of the piston rod adjacent the rear face of the
piston and communicates with the bore 238 adjacent the
axially inner end thereof. The radially outer end of
transverse passage 239 communicates with a chamber 2~1
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which is formed within the sleeve 219 and is located between
the opposed axial faces of the piston 226 and the end
hub 222A when the piston 226 is moved slightly inwardly
away from the end hub as shown in Figure 9.
To control flow through the passage arrangement defined
by the passages 237, 238 and 239, there is provided a movable
valve member in the form of a ball 243 which is adapted to
seat against an annular conical valve seat 242 formed at the
junction between the bores 237 and 238. The ball 2g3 is
disposed in the large bore 237 and is of a larger diameter than
the bore 238. The ball 243 is confined in the bore 237 by the
locking pin 232 which extends diametrically across the bore
237 but is spaced axially a small distance from the ball 243
to permit movement of the ball away from the seat 242 so
as to permit flow through the passage arrangement.
The inner control sleeve 219 has small holes247 formed
through the wall thereof and communicating at the radially
outer ends with an outer annular chamber 246 formed between
the sleeve assembly 213 and the outer housing sleeve 216.
The holes 247 are disposed adjacent the leftward end of the
sleeve 219, which end has the piston 226 associated there-
with when the shock absorber is in its extended position.
The holes 247 are positioned directly adjacent the inner
axial face of the hub 222A so that the holes thus communicate
with the chamber 241 at all times. One of the holes 247
has the radially inner end thereof joined in flow communica-
tion with an axially extending groove 248 formed in the
inner wall of the sleeve 219, which groove 248 terminates at
a location which is disposed slightly forwardly of the
front face of the piston 226 when the ram assembly is in its
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fully extended position.
The flow control sleeve assembly 213 also includes an outer
cylindrical control sleeve 251 disposed concentric with and
in surrounding relationship to the inner conrol sleeve 219.
The outer sleeve 251 has the rightward end thereof axially
spaced from the end member 217, whereby outer sleeve 251
can thus be moved axially through a limited extent relative
to the inner sleeve 219.
The control sleeves 219 and 251 have opposed conical
surfaces formed thereon for permitting adjustment in the
energy absorption characteristic of the shock absorber~
For this purpose, the outer control sleeve 251 has an inner
conical surface 253 which is disposed opposite and is adapted
to be engaged with an outer conical surface 2~4 as formed on
the inner control sleeve 219. The conical surfaces 253
and 254 are of an identical taper, which taper preferably
extends at a small angle relative to the longitudinally ex-
tending axis A of the shock absorber. In the illustrated
embodiment, the taper of the conical surfaces is normally
in the range of between 1 and 5, and preferably 2, al-
through the present invention also contemplates the use of
a larger angle of taper. The conical surfaces 253 and 254
are maintained substantially in engagement with one another
when the sleeve assembly 213 is in its fully closed posi-
tion, in which position the outer sleeve 251 is in its left-
ward most position.
To provide for controlled flow of fluid from the inner
chamber 227 through the sleeve assembly 213 to the outer
chamber 246, which controlled flow permits the absorption
of energy when a shock load is imposed on the absorber,
z~
the inner and outer control sleeves are relatively moved
into a position in which the opposed conical surfaces 253
and 254 are spaced a small distance apart so as to result
in the formation of a small annular space 256 therebetween.
The inner control sleeve 219 is provided with a pair of
elongated slots 257 (Figures 10-12) formed in the outer
conical surface 254 thereof~ which slots 257 extend axially
of the sleeve 219 throuyhout substantially the complete
length of the outer sleeve 251. The slots 257 terminate,
at the leftward ends thereof, in openings 258 (Figure 12)
which communicate with the outer chamber 2~6. The slots
257 are disposed closely adjacent and on opposite sides of
an axially extending row of openings 261 which are formed
in the inner sleeve 219 and communicate with the inner
chamber 227. The slots 257 and their relationship to the row
of openings 261 results in the formation of narrow circum-
ferentially extending lands 262 between the row of openings
261 and the adjacent slots 257. The lands 262 are adapted
to be spaced from the opposed inner conical surface 253 and
thus define narrow flow control passages 263 therebetween
for controlling the fluid flow from the openings 261 into
the slots 257.
The outer control sleeve 251 is axially adjustable re-
lative to the inner control sleeve 219 so as to vary the
radial width or dimension of the passages 256 and 263. For
this purpose, there is provided an adjustment structure 266
which includes a knob or handle 267 fixedly secured to the
outer end of a control shaft 268, which control shaft is in
turn rotatably and sealingly suppor-ted on a housing hub
269 so that the control shaft is rotatable about an axis
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~(~SB~Z91
which extends substantially perpendicular to the axis A.
Control shaft 268 is axially restrained with respect to
the housing hub 269 by means of a locking pin 271. Control
shaft 268 has a cam or eccentric 272 fixedly secured to
the inner end thereof, which eccentric is disposed within
an opening or slot 273 formed in the outer control sleeve
251. The eccentric 272 is preferably of circular cross-
section and has the axis thereof eccentrically displaced
from the axis of the shaft 268, whereby eccentric 272 func-
tions like a crankpin. The slot 273 has a width, as mea-
sured in the axial direction of the control sleeve 251, which
substantially corresponds to the diameter of the eccentric
272 so that same is snugly accommodated in the slot.
However, slot 273 has a length, as measured circumferentially
of the control sleeve, which is preferably greater than the
diameter of the eccentric to thereby compensate for the side-
ward displacement of the eccentric during rotation of the
control shaft 268.
The control shaft 268 is rotatable through an angle
of approximately 180, and preferably slightly less, so as
to cause a corresponding rotation of the eccentric 272,
which in turn causes axial displacement of outer control
sleeve 251 between two endmost positions. When the adjust-
ment structure is in the position illustrated in Figure 9,
in which position the eccentric 272 is in its leftward end
position, the outer control sleeve 251 effectively abuts
against a stop 274 (Figure 12) as formed on the inner
control sleeve 219, thereby resulting in a minimum clearance
between the conical surfaces 253 and 254 so that the open-
ings 261 are effectively closed. The presence of the stop
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~5~2'~1
274, however, prevents the two conical surfaces 253 and
254 from being lockingly wedged together.
When the control knob 267 and eccentric 272 are rotated
away from the position illustrated in Figure 9, then the
outer control sleeve 251 is moved axially rightwardly
so that the spacing 256 between the conical surfaces 253
and 254 is increased, with the maximum spacing existing
when the sleeve 251 is in its rightward most position.
Rotation of knob 267 thus permits the spacing between the
conical surfaces to be selectively varied and adjusted
to provide for the desired restricted flow of fluid from
the inner chamber 227 into the outer chamber 246 when the
ram assembly 212 is moved inwardly into the housing 211.
The shock absorber can be suitably locked in its select-
ed position by means of a set screw 276 which locks the knob
267 to the housing hub 269 and thereby fixedly maintains
the positional relationship between the control sleeves 219
and 251. Set screw 276 is positioned substantially parallel
to the axis of the control shaft 268 and thus projects per-
pendicularly from the side of the housing so as to be readily
accessible for adjustment, as by means of an Allen wrench
or other tool.
The ram assembly 212 has an enlarged head 278 on the
outer free end of the piston rod 228, which head 278 is
adapted to have the shock loads imposed thereon, and a
conventional compression spring 279 surrounds the piston
rod 228 and is confined between the head 278 and the bushing
222 to thereby continuously urge the ram assembly into
its outward extended position.
Housing 211 has a port 281 associated therewith to
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permit the shock absorber to be filled with fluid, such
as hydraulic oil. This port is normally closed by means
of a conventional plug. Chamber 246 also preferably has
a compressible spongelike member 282 positioned therein
so as to compensate for volume changes caused by the inward
movement of the piston rod, which member 282 substantially
encircles the sleeve 251 throughout the axial extent
thereof. The member 282 is preferably of a rubber or
plastic closed-cell structure.
The operation of the embodiment shown in ~igures 9-13
is believed readily apparent from the above structural and
operational descriptions.
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