Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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END CAP ASSEMBLY FOR AIR SPRING
TECHNICAL FIELD
The invention herein resides in the art of
air springs. More particularly, the invention relates
to an air spring formed from a tubular elastomeric
sleeve wherein sealing beads are mechanically formed at
the ends thereof eliminating the heretofore required
separate reinforcing beads mounted within the ends of
the tubular sleeve.
BACKGROUND ART
Air springs are well known in the art and
comprise an elastomeric sleeve which is maintained
between a pair of end members adapted primarily for
implementation in motor vehicles for supporting the
vehicle body. The air springs are sealed at the ends
by the end members to form a pressurized fluid chamber
within the sleeve. ~einforcing beads previously have
been molded about or within the peripheries of the
sleeve ends to provide for a fluid tight seal with the
end members. It has also been known to seal the ends
of the sleeve forming the air spring by means of
complex mechanical structures, typically incorporating
metallic plates and the like secured by means of bolts
or other fastening means. These sealing structures are
both time consuming and expensive in implementation.
Previously known structures of the general
nature set forth herein are shown in U.S. Patents
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2,874,458; 2,977,134; 3,038,717; 3,790,147; 4,325,541;
4,506,910; and British Patent 907,555. None of these
references, however, teach an air spring which may be
quickly and effectively formed from a tubular
elastomeric sleeve without a separate reinforcing bead
and wherein the bead is formed and sealed by simple
engagement of snap-fitting together parts of metal
and/or plastic. The teachings of the prior art have
been expensive as to both time and material involved
and, due to the metallic parts and separate bead rings
previously used, have been a source of undesired weight
in a vehicle.
Furthermore, in existing air springs as the
internal pressure increases the separation forces
acting on the sleeve end seals increases thereby
limiting the amount of internal pressure which can be
utilized for the air spring.
Accordingly, there is desire in the art for a
simplistic and inexpensive air spring which is formed
from a tubular elastomeric sleeve, the ends of which
are sealed by mating parts which seal the unit and form
a pressurized fluid chamber without requiring the
installation of separate reinforcing beads within the
sleeve ends during formation of the tubular sleeve.
DISCLOSURE OF THE INVENTION
In light of the foregoing, it is a first
aspect of the invention to provide an air spring
without separate mechanical reinforcing beads molded
within the ends of the sleeve.
Another aspect of the invention is the
formation of an air spring wherein the beads`are formed
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from the elastomeric material of the sleeve ends bv the
clamping engagement of mating members.
Still a further aspect of the invention is to
provide an air spring wherein compressive forces on the
air spring and the force exerted by the trapped fluid
tighten the clamping action of the end mating members
against the formed beads.
An additional aspect of the invention is the
formation of an air spring in which the mating end
members may be molded of plastic or similar materials,
greatly reducing both weight and cost of the air
spring.
Still another aspect of the invention is
providing an air spring which may be formed by
snap-fitting together the end components which seal the
tubular sleeve without nuts, bolts, or other
torque-applied connectors.
A further aspect of the invention i5 the
sealing of the end members with the sleeve ends by
forming a pair of spaced apart pinch areas in the ends
of the sleeve by the configuration of the mating
members which places the sleeve in compressive shear at
the two pinch areas, in combination with an intervening
expansion area which changes the direction of the
reinforcing cords molded within the sleeve ends
approximately 180 which distributes the pulling force
caused by the internal air pressure within the sleeve
across the two pinch areas to enable the mating end
members to withstand greater internal fluid pressure
than heretofore possible without the use of separate
reinforcing bead rings.
Another aspect of the invention is the
formation of an air spring wherein the molding of a
separate bead reinforcement within the ends of the
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sleeve is completely eliminated with the bead
reinforcement function being provided by the pair of
compressive shear pinch areas and intervening expansion
area affected by the mating end components.
A further aspect of the invention is the
providing of an air spring wherein the tensile load on
the reinforcing cord changes 180 at two compressive
shear pinch areas wherein the tensile load is in
downward direction at one pinch area and in an upward
direction at the other pinch area, and in which a third
pinch area may be provided to assist in distributing
the pulling force caused by the internal pressure
across three different pinch areas which, in
combination with the change of direction of the
internal cord, provides an extremely strong and
satisfactory seal for the ends of the elastomeric
sleeve without internal bead reinforcement or other
external sleeve clamping means.
The foregoing and other aspects of the
invention which will become apparent as the detailed
description proceeds are achieved by an air spring, the
general nature of which may be stated as including a
pair of end members adapted to be mounted at spaced
locations; a flexible sleeve formed of an elastomeric
material containing reinforcing cords and having open
ends sealingly engaged with the end members forming a
pressurized fluid chamber therebetween; one of said end
member having an end cap extending within one of the
open ends of the sleeve and a clamp ring extending
about said one sleeve end in clamped engagement with
said end cap compressing the sleeve material
therebetween; and an annular curved projection formed
on a mating surface of one of said end cap and clamp
ring extending into a concave recess formed in a mating
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surface of the other of said end cap and clamp ring
placing the sleeve in compressive shear througho~t two
spaced annular areas on opposite sides of said
projection, and an intervening area within said recess
between said annular compressive shear areas having a
greater separation than the thickness of the sleeve
material to permit the sleeve material to expand
therein.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention,
illustrative of the best mode in which applicant has
contemplated applying the principles, are set forth in
the following description and are shown in the drawings
and are particularly and distinctly pointed out and set
forth in the appended claims.
FIG. 1 is a diagrammatic perspective view of
the improved air spring of the invention;
FIG. 2 is an enlarged fragmentary vertical
cross-sectional view of the improved air spring of FIG.
l;
FIG. 3 is a further enlarged fragmentary
sectional view of the snap-fitted connection of the end
cap and clamp ring of the upper end member of the air
spring of FIGS. 1 and 2;
FIG. 4 is an exploded fragmentary view with
portions in section showing a modified end member for
sealing the ends of the sleeve of the improved air
spring of the invention in disassembled position;
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FIG. S is a fragmentary sectional view of the
modified end member of FIG. 4 in assembled position;
and
FIG 6 is a greatly enlarged fragmentary
sectional view showing the various pinch areas and
expansion areas provided by the modified end member of
FIGS. 4 and 5.
Similar numerals refer to similar parts
throught the drawings.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to the drawings and more
particularly to FIGS. 1 and 2, the improved air spring
of the invention is indicated generally at 10. The
center portion of air spring 10 is formed by a
cylindrically tubular-shaped sleeve 12 which is formed
to an appropriate length from suitable elastomeric
material 13 containing reinforcing fabric formed by
biased cords 14, shown particularly in FIG. 3, without
a separate reinforcing bead being molded into either
end of the sleeve as in prior art sleeve constructions.
An end cap assembly or end member indicated generally
at 15, is secured to sleeve 12 at opposite ends
thereof. Cap assemblies 15 are adapted to be secured
to portions of a vehicle or other spaced structures
between which relative movement is to be dampened. The
uses of the air spring of the instant invention are no
different from those previously known, the invention
herein residing in the structure and more particularly
the sealing of the sleeve ends to form a pressurized
fluid chamber 18 therein by end cap 15.
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Each end cap assembly 15 preferably is
similar and therfore only one is shown and described in
detail End cap assembly 15 comprises a generally
disc-shaped end cap 16 interconnected with an annula.
clamp ring 20 Ring 20 comprises an ou~er cylindrical
side wall 22 which is normal and upstanding to an
annular base 24 (FIG 3)
In accordance with the main feature of the
invention the inner end of annular base 24 terminates
in an upwardly extending projection 26 which is spaced
radially inwardly from sidewall 22 and which terminates
in a rounded top end 28. An annular concave recess 29
is formed outwa.dly of p.ojection 26 and is separated
from sidewall 22 by an annular shoulder 30 also formed
as a part of base 24 The inside surface of wall 22 is
cylindrical and terminates in a snap-lip 31 having a
beveled edge 32. The inner surface of ring 20 defined
by projection 26, concave recess 29, shoulder 30, and
cylindrical inner surface 33 of cylindrical wall 22 is
collectively referred to as a mating surface and is
indicated generally at 35.
End cap 16 is formed with an inner mating
surface indicated generally at 37, formed with a main
inner concave recess indica.ed generally at 38 which
axially aligns with and receives a portion of
projection 26 of clamp ring 20 Mating surface 37
further includes an annular relatively flat radially
extending area 39 which terminates in an outwardly
tapered inclined annular surface 40 which converges
toward sidewall 22 of clamp ring 20. Surface 40
terminates in a snap-lip 42 having a beveled surface 43
which is clampingly engaged with beveled edge 32 of
snap-lip 31
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One of the main features of the .nvention i5
the alignment of mating surfaces 35 and 37 to form a
pair of pinch areas indicated at 45 and 46 ( FIG. 3)
located between the axially extending side surfaces 48
of projection 26 and the generally parallel axially
extending side surfaces 50 which fo-m concave recess
38. The radial distance between aligned surfaces 48
and SO, which are generally parallel to each other as
shown in FIG. 3, is preferably approximately 50% of the
uncompressed thickness of elastomeric material 13 of
sleeve 12. Thus upon the axial engagement of end cap
16 with clamp ring 20, the elastomeric material in the
pinch areas indicated at 52 and 53, is placed in shear
compression securing the sleeve tightly therebetween.
In further accordance with the invention,
rounded the top end 28 of projection 26, is spaced f~om
bottom surface 55 of concave recess 38 a distance
greater than the thiclcness of material 13 providing an
expansion zone or area for movement of the comp.essed
rubber in the pinch areas to expand or flow into the
expansion area which is indicated at 56.
As shown in FIG. 3, reinforcing cord 14 moves
through a direction change of approximately 180 when
moving from pinch area 45 through expansion area 56 and
then through pinch area 46. This change of direction
places a downward tensile load on the cord as shown by
arrow A in moving through pinch area 45 and placing an
upward tensile load on the cord as indicated by arrow
B, when moving through pinch area 46. The par.icular
configuration of mating surfaces 35 and 37 has been
found to provide the required clamping action and force
on sleeve 12 to maintain it in a secured clamped
posit;on between end cap 16 and clamp ring 20.
The bottom of concave recess 29 of clamp ring
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20 is spaced a sufficient distance, a distance greater
than the thickness of material 13, from flat radial
surface 39 of end cap 16 to provide a second expansion
area 58. This is followed by a third pinch area 59
formed between annular shoulder 30 and radial flat
surface 39 providing additional holding and clamping
action on the sleeve end. An outer expansion area 60,
having a generally triangular configuration, is formed
between end cap tapered surface 40 and inner
cylindridal surface 33 of clamp ring sidewall 22 .o
permit any remaining rubber caused by pinch area j9
which does not flow into expansion area 58 to have a
void area in which to flow to permit the sa.isfactory
snap joining of end cap 16 with clamp ring 20.
The pa.ticular configuration of mating
surfaces 35 and 37 causes the elas,omeric material of
sleeve 12 to form around various contours, and when
combined with the pinch areas and expansion areas, has
been found to provide an ex,remely strong clamping
action between the end cap and sealing ring enabling
the internal pressure within chamber 18 to be increased
to a pressure at least equal to that provided by end
clamping members in which the sleeve has internally
molded reinforcing clamping beads or bands.
Since the rubber or elastomeric material 13
is generally incompressible after reaching a certain
amount of compression, expansion areas 56, 58 and 60
are provided to ensure a proper clamping action between
cap 16 and ring 20 a. spaced pinch areas 45, 46 and 59
for securely clamping the sleeve therein. The change
of direction of fabric cord 14 as it moves through the
spaced pinch areas and intervening expansion area and
into the final expansion areas is believed to provide
the resistance to the disengagement of the clamped
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sleeve material from between end cap 16 and ring 20.
End cap 16 is formed with a plurality of threaded holes
54 for securing the end cap to a vehicle or the like
with upper end cap 16 being provided with a threaded
opening 62 for receiving the nipple of a pressure valve
for connecting the air spring to a pressure source for
pressurizing chamber 18.
With continued reference to FIGS. 1 - 3, it
can be seen that end cap 16 may be easily positioned at
the end of the sleeve 12. To do so, the bead ring 20
is first slid over the outer periphe.y of elastomeric
sleeve 12 a predefined distance. With the inner
diameter of the ring 20 being less than the outer
diameter of the sleeve 12, the rubber of sleeve 12 is
drawn inwardly within the ring. Next, the end cap 16
is brought within the end opening of sleeve 12 as it
extends through ring 20, securing the elastomeric
material of the sleeve between the outer peripheral
contoured mating surface 37 of end cap 16 and the
generally similarly shaped inner mating surface 35 of
ring 20. The clamping forces developed between mating
surfaces 35 and 37 as discussed above prevent sleeve 12
from slipping or moving while end cap 16 is engaged
with ring 20.
It will be readily appreciated that, in
operation, end cap assemblies 15 are secured to
relatively movable members such as on a vehicle. It
will also be understood that fluid pressure chamber 18
defined by the sleeve 12, is pressurized to provide the
spring action. With movement of the end caps
relatively restricted, the pressure force within
chamber 18 exerts radial, rather than axial force on
the mating seals defined by the spaced concentric
projections and recesses of the mating surfaces
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maintaining compressed sleeve material therebetween.
This force tends to increase the effectiveness of
sealing or clamping action as the internal pressure
increases.
A modified form of the improved air spring,
and in particular, the end cap assembly therefor~ is
indicated generally at 64 and is shown in FIGS. 4~ 5
and 6. The modified end cap assembly includes anend
cap and clamping ring indicated generally at 65 and 66
respectively. End cap 65 is a solid disc-shaped member
having an outer surface 67 formed with a helical
projection 68 which forms a intervening helical-shaped
recess 69. Helical projection 68 is formed with
rounded outer surfaces 73 to prevent cutting into
elastomeric material 13 as described below. As shown
in FIG. 5 a plurality of threaded mounting holes 71 and
a threaded pressure supply opening 72 are provided ln
end cap 65 for mounting the air spring to a supporting
structure and to provide for the flow of pressurized
fluid into fluid chamber 18 of the air spring in a
usual manner well known in the art. Clamp ring 66 is
annular-shaped having an inner mating surface indicated
generally at 75, formed by an helical projec.ion 76
forming an intervening helical-shaped concave recess
77.
Referring to FIGS. 4 and 5, the outer end of
sleeve 12 is inserted through the interior of clamp
ring 66 followed by the engagement of end cap 65
therein by a rotational motion similar to the threaded
engagement of an externally threaded member into an
internally threaded opening. In accordance with the
principles of the invention, helical projection 68 of
end cap 65 extends into helical concave recess 77 of
clamp ring 66 as shown in FIG. 6 to provide a series of
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pinch areas or zones, each of which is indicated by
numeral 79. These pinch areas are followed by
intervening expansion areas 80 whereby at leas~ a pair
of compressive shear areas are applied on the
elastomeric material of sleeve 12 separated by an
expansion areas whereby the rubber squeezed from the
shear compressive areas flow into the intervening
expansion area. Furthermore, cord 14 moving through a
change in direction of approximately 180 when moving
from one pinch area into a second pinch area with the
tension exerted on the cord also reversing from an
innward to an outward direction with respect to the
longitudinal dimension or axis of sleeve 12 in a
similar manner as described above with respect to end
cap 16 and clamp ring 20.
Again, the combination of two pinch areas
between the end cap and clamp ring which forms the pair
of pinch areas to place the intervening sleeve material
in shear compression, together with the in.ervening
expansion zone, has been found to provide a secure
clamping engagement with the sleeve end to enable the
air spring to withstand sufficient internal pressure
for its desired application.
Accordingly, the improved beadless air spring
is simplified, provides an effective, safe,
inexpensive, and efficient device which achieves all
the enumerated objectives, provides for eliminating
difficulties encountered with prior devices, and solves
problems and obtains new result in the art.
In the foregoing description, certain terms
have been used for brevity, clearness and
understanding; but no unnecessary limitations are to be
implied therefrom beyond the requirements of the prior
art, because such terms are used for descriptive
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purposes and are intended to be broadly construed.
Moreover, the description and illustration of
the invention is by way of example, and the scope of
the invention is not limited to the exact details shown
or described.
Having now described the features,
discoveries and principles of the invention, the manner
in which the improved beadless air spring is
constructed and used, the characteristics of the
construction and the advantageous, new and useful
results obtained; the new and useful structures,
devices, elements, arrangements, parts and combinations
are set forth in the appended claims.
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