Miniature vibration isolator utilizing elastic tubing materia

Butler, D. H.

Falk, W. C.

English

NASA Technical Reports Server

REPLY TO 
ATTN OF: 
TO: 
FROM: 
SUBJECT: 
NATIONAL AERONAUTICS AND SPACE ADM~NISTRATI~N 
WASHINGTON, D.C. 20546 
October 12, 1970 
USI/Scientific & Technical Information Division 
Attention: Miss Winnie Mr Morgan 
GP/Of f ice of Assistant  General 
Counsel f o r  Patent Matters 
Announcement o f  NASA-Owned 
U.S. Pat@nts i n  STAR 
I n  accordance with the procedures cont 
to Code US1 memorandum on thier ~lubject 
the attached NASA-owned U.6, pat 
abstracting and announcement in 
The fo%lowing information i 
U.S. Patent No. 8 I 3,223,374 
corporate Sourc t 
FI 
0 
9 
(CODE) 
5 
2 
tr I /5 
(CATEGORY) 3 
y n (NASA CR OR TMX OR AD NUMBER) 
https://ntrs.nasa.gov/search.jsp?R=19700030840 2020-03-17T02:09:25+00:00Z
Dec. 14, 1965 D. H. BUTLER ETAL 
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FIG. 4 
MINIATURE VIBRATION ISOLATOR 
Filed May 23, 1963 
FIG. I 
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FIG. 3 
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BY 
FIG. 5 
W E N T O R S  
DAVID H. BUTLER 
WILBERT C. FALK 
a 
3,223,374 
David H. Butler and Wilbert C. Falk, Hampton, Va., as- 
signors Lo the United States of America as represented 
by the Adminisirator of the National Aeronautics and 
Space Administration 
Filed May 23,1963, Ser. No. 282,817 
12 Claims. (C1.248-358) 
(Granted under Title 35, US. Code (1952), sec. 266) 
The invention described herein may be manufactured 
and used by (or for the Government of the United States 
of America for governmental purposes without the pay- 
ment of any royalties thereon or  therefor. 
This invention relates to a vibration isolator, and more 
particularly to a vibration isolator which is adapted for 
use with the miniaturization technology. 
There are numerous types of vibration isolators avail- 
able commercially; however, as a general rule they do not 
lend themselves to  use in the field of miniaturization. 
Most of these isolators are constructed from elastomer 
compounds such as rubber and modified rubber com- 
zpounds. Although they are effective isolators for the pur- 
pose designed, they are normally large and bulky and d o  
not adapt themselves to an environment such as the in- 
stallation of equipment in a compact missile payload con- 
struction. Commercially available isolators require more 
space than is often available and may be difficult to install 
or assemble in a limited space environment. In certain 
compact equipment construction it is necessary for the 
workman to work blind; therefore, the particular assembly 
of the isolator must be extremely simple and essentially 
foolproof. 
Other types of vibration isolators include things such 
as springs, cables, and wire mesh. These are also opera- 
tive for the purposes intended, but are not particularly 
adapted to miniaturization. The cost of manufacturing 
such resilient metallic structures in very small sizes is (often 
excessive. Furthermore, it is difficult to design the neces- 
sary elasticity into metallic members to be utilized in the 
space available in the compact arrangements. 
The above problems are overcome by the present inven- 
tion wherein a vibration isolator is constructed by com- 
pressing a piece of elastic tubing in a manner such that it 
folds upon itself to provide the necessary damping be- 
tween mem'bers to alleviate the transmission of vibration 
of one member to another. 
It is, therefore, an oibject of this invention to provide a 
vibration isolator which is particularly adapted for use in 
miniaturization technology. 
Another object of this invention is to provide a vibra- 
tion isolator which consists of a minimum number of 
component parts which are of extremely simple design. 
Yet another object of this invention is to provide a 
vibration isolator which lends itself to assemibly in compact 
areas. 
Still another object of this invention is to provide a 
vibration isolator which adapts itself readily to various 
size requirements. 
Another opbject of this invention is to provide a vibra- 
tion isolator wherein a n  elastic material is utilized which 
when compressed will buckle to form beads of resilient 
material between the members being isolated. 
These and other objects and advantages of this inven- 
tion will bewme more apparent upon reading the specifica- 
tion in conjunction with the accompanying drawings. 
AT&TRE VIBRATION ISOLATOR 
In the drawings: 
FIG. 1 is a plan view of an equipment installation utiliz- 
ing vibration isolators according to the present invention; 
FIG. 2 is a side elevational view of an equipment in- 
stallation utilizing vibration isolators according to  the 
present invention; 
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FIG. 3 is a cross sectional view taken along the section 
lines 111-111 of FIG. 1, showing the details of the vibra- 
tion isolator; 
FIG. 4 is an exploded cross-sectional view as in FIG. 3, 
showing the manner of assembly of the vibration isolator; 
and 
FIG. 5 is a cross sectional view showing a modified 
form of a vibration isolator. 
Basically, this invention relates to  a vibration isolator 
which is particularly adapted for use in attaching compact 
equipment packages to support structure. In accomplish- 
ing the purposes and intent of the invention the equipment 
package and support structure are provided with a plural- 
ity of aligned apertures. The apertures in one of the 
members are enlarged and receive elastic tubing which fit 
therethrough and abutt the other member. The elastic 
tubing projects on either side of the member with the en- 
larged apertures. Cup-like washers engage and surround 
the non-abutting ends of the elastic tubes. Fasteners, 
such as screws, pass through the cup-like washers, the 
tubes and the apertures, and engage nuts. When the 
screws are tightened the elastic tubes are oompressed and 
caused to buckle forming resilient beads between the mem- 
bers and one of the members and the cuplike washers. 
Referring now more specifically to the details of the 
invention, FIGS. 1 and 2 show an equipment assembly, 
designated generally by the reference numeral 10. The 
equipment assembly 10 further includes generally the 
equipment package 12, the support structure 18 and the 
vibration isolator assemblies 25. 
The equipment package 12 may be any one of a number 
of items, but for purpioses of illustration it will be consid- 
ered an electronic transmitter. The transmitter is located 
within a housing 13 in a conventional manner. The hous- 
ing 13 has flanges 14 which are provided with apertures 15 
at spaced intervals along either side of the housing. 
The support structure 18 may be any structure which 
is available to support the equipment package. In a mis- 
sile payload it may be the base of the payload or the side 
of the payload, depending upon the space available and 
the desired location of the equipment. The support struc- 
ture is provided with apertures 19 which are located so as 
to be in alignment with the apertures 15 formed in the 
flanges in the equipment package. Nuts 20 may be 
formed integral with the support structure as shown in 
FIGS. 2 and 3 lor may be of a conventional design. In 
constructing a missile gayload it is often necessary to  
form the nuts integral with the support structure since the 
equipment is placed in tiers or in other arrangements 
whereby the bottom of the support structure is not aoces- 
sible. For purposes of illustration the apertures 15 are 
shown in a larger diameter than the apertures 19; however, 
it is to be understood that within the broadest aspect of 
the invention this arrangement may be reversed as the situ- 
ation demands. The nuts 20 are provided with threads 21 
to receive the threads of bolts or screws which form a part 
of the vibration isolator assembly 25 nlow to be described. 
The vibration isolator 25 is best illustrated in FIGS. 3 
and 4. FIG. 3 shows a vibration isolator in the assembled 
position and FIG. 4 shows it before assembly. The as- 
sembly includes a bolt 2.6 which has a head 27 and shank 
28. A portion of the shank 28 is provided with threads 
29. 
The assembly 25 also includes a cup-like washer or 
counterboard washer 32. The washer 32 has a central 
aperture or opening 33 and lip or flange 34. 
The damping component of the vibration isolator as- 
sembly 25 is an elastic or resilient tube 36. The tube 36 
has a central passage 37 and may be constructed from 
materials such as rubber, neoprene, silicon rubber or vari- 
ous other elastomer compounds. The tubing is of a thick- 
ness such that when compressed it will buckle and fold 
3,223,374 
3 
upon itself to form beads 38 and 39 as shown in FIG. 3. 
The beads 38 and 39 are thus a double layer of the tubing 
forming an effective isolation structure between the equip- 
ment package 14 and support structure 18. 
A modified form of vibration isolator is shown in FIG. 
5, designated generally by the reference numeral 42. In 
this arrangement the isolator assembly includes a bolt 
43, top washer 44 and elastic tube 45 all similar to these 
elements in isolator assembly 25. The arrangement dif- 
fers in that a bottom cup-like washer 46 engages the end 
of the elastic tube which would otherwise normally abutt 
against the support structure. The bottom washer 46 is 
identical to the top washer 44 and may be used inter- 
changeably. The bottom washer 46 assumes a position 
opposite the washer 45 for purposes now to be explained 
in the assembly and operation of the invention. 
ASSEMBLY AND OPERATION 
The assembly of the vibration isolator is best illustrated 
in FIG. 4. The apertures 15 and ,19 in the equipment 
package and support stmcture are aligned. The elastic 
tubes 36 are cut to a length such that sufficient material 
will project on either side of the member through which 
the tubes are to be passed so that when the tube is placed 
under compression it may collapse and form the beads 
38 and 39. The elastic tubing is normally centered such 
that an equal amount of material projects on either side 
of the members through which it is fitted so that beads of 
approximately the same size will be formed on either side 
of the member. The cup-like washer 32 is placed on 
the end of the elastic tube 36 which is opposite to the end 
of the tube which will abutt the structural member 18 as 
shown in FIG. 4. The shank 28 of bolt 26 is threaded 
through the opening 33 in the washer, through the tube 
passage 37, the aperture 19 in the support structure 18 
and the threads 29 thereof are engaged with the threads 21 
of nut 20. 
In operation the screw 26 is tightened compressing the 
elastic tube 36. The lip 34 on washer 32 prevents the 
end of the elastic tube from expanding thereby forcing 
it to buckle outwardly forming the bead 38. The portion 
of elastic tube 36 located between the instrument package 
flange 14 and the support structure 18 behaves similarly 
forming the bead 39. It has been found that the elastic 
tube section between the flange 14 and support structure 
18 will buckle outwardly as long as the abutting end of 
the elastic tube engages a large surface area on the mem- 
ber 18. Should the necessary surface area of the support 
member 18 be absent, an additional cup-like washer or 
bottom washer may be utilized as shown in FIG. 5 by vi- 
bration isolator assembly 42. 
Under certain assembly procedures it may be desirable 
to bond the elastic tube to the partioular member through 
which it is fitted. This is particularly desirable when the 
workman is functioning blind, this meaning the area of 
the elastic tube between the members is not open to visual 
inspection. With this arrangement it may be also desir- 
able to fix a bottom washer in place by conventional tech- 
niques. Normally, however, the bonding procedure is not 
necessary as long as the elastic tube has a snug fit with 
the aperture through which it passes. 
Although the vibration isolator is shown as being uti- 
lized as a means for damping vibration between an equip- 
ment package and a support structure, it is to be under- 
stood that the principle can be applied to several tiers of 
plates rather than two as illustrated. Thus, the elastic 
tube could pass through two or three apertures formed in 
tiers or stacks of separated plates. Furthermore, the prin- 
ciple could be applied to the assembly, such as shown in 
FIG. 3, in manner such that the elastic tube would pass 
through the apertures in both the equipment package and 
the sumort structure. the auertures being the same size 
4 
form a bead on either side of the equipment package and 
support structure, as well as between these members. Ob- 
viously, the arrangement in FIG. 3 can be reversed such 
that the enlarged apertures placed in the support structure 
5 rather than in the equipment package and the vibration 
isolator assembly 25 reversed. 
From the above description it is clear that the vibration 
isolator of this invention is of an extremely simple de- 
sign. Outside of the screw, the assembly includes only 
the piece of elastic tubing and the cup-like washer. The 
invention is readily adaptable to different sizes by merely 
selecting the proper size of tubing. Production costs are 
minimized by using commercially available elastic tubing 
since it is not necessary to cut or form grooves in the tcbe, 
15 the beads being formed from the tube itself upon compres- 
sion thereof in assembly. The device is particularly s i t e d  
for use in the miniaturization field since very small tubing 
can be utilized and still have the capability of buckling to 
form the beads necessary for vibration isolation. The 
2o quantity of elastic materials utilized is less than that of 
existing isolators using elastomer compounds. The tubing 
to be operative must be thin enough under compression to 
buckle and form beads. With existing structures the 
beads must be formed from an original piece of stock 
25 which has several times the thickness of the piece of tub- 
ing utilized in the instant invention. It should also be 
noted that the tubing readily passes through an aperture 
for assembly purposes even though it fits snugly. Much 
more difficulty is experienced in installing a bead which 
30 is half again or twice the size of the aperture throagh 
which it is being passed. Of course, there is less chance 
of damage to the tubing than with the arrangement where 
the bead is already formed and forced through a smaller 
hole. Also, by selecting tubing of various elastomers and 
35 durometer hardness the stiffness of the isolator can be 
readily changed, providing a range of isolator natural fre- 
quency response. Similarly by selection of tubing the 
optimum size and weight is readily available, particularly 
important in the compact missile payload constnuction. 
What is claimed as new and desired to be secured by 
Letters Patent of the United States is: 
1. A miniature vibration isolation assembly compris- 
ing: a first member; a second member to be mounted 
in spaced relation to  said first member; said first and 
second members having aligned apertures; the aperture 
45 in one of said members being larger than the aperture in  
the other member; an elastic tube fitting through the: 
large aperture and abutting said other member; a CUP- 
like washer engaging and surrounding the nonabutting 
end of said elastic tube; fastener means passing through 
said apertures, tube and cup-like washer; and folded beads 
formed between said first and second members and one 
of said members and said cup-like washer upon com- 
pression of said elastic tube to isolate said members. 
2. A miniature vibration isolation assembly compris- 
ing: a first member; a second member t o  be mounted 
in spaced relation to said first member; said first and 
second members having aligned apertures; elastic means 
located within the aperture in one of said members; fas- 
60 tener means passing through said elastic means and 
said apertures; means engaging said elastic means upon 
tightening said fastening means whereby said elastic 
means is caused to fold upon itself forming beads to isolate 
said members. 
3. A miniature vibration isolation assembly as in claim 
2 wherein said means engaging said elastic means is a 
a cup-like washer. 
4. A miniature vibration isolation assembly as in claim 
?o 2 wherein said means engaging said elastic means is a 
pair of cup-like washers a t  opposite ends of said elastic 
means. 
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rather-ihan of a differential size as shown. With this 
arrangement a top and bottom cup-like washer would be 
utilized and the elastic tube upon being compressed would 75 
5. A miniature vibration isolation assembly as in claim 
2 wherein said elastic material is made from neoprene. 
6. A miniature vibration isolation assembly as in claim 
3.223,374 
5 
2 wherein said elastic material is made from silicone 
rubber. 
7. A miniature vibration isolation assembly as in claim 
2 wherein said elastic means has a substantially uniform 
cross-sectional dimension throughout. 
8. A miniature vibration isolation assembly compris- 
ing: a first member; a second member to be mounted in 
spaced relation to  said first member; said first and second 
members having an aligned aperture; an elastic tube fit- 
ting through a t  least one of said apertures; cup-like 
washers engaging and surrounding the ends of said elastic 
tube; fastener means passing through said apertures, the 
elastic tube and said cup-like washers; and folded beads 
formed in the elastic tube upon .tightening said fastener 
to isolate said members. 
9. A miniature vibration isolation assembly as in claim 
8 wherein said elastic tube is bonded to structure forming 
the aperture of at least one of said members to facilitate 
assembly and the folding of the tube upon itself. 
10. A miniature vibration isolation assembly as in 
claim 8 wherein said fastening means includes a nut 
formed integral with at least one of said members to 
facilitate assembly. 
11. A miniature vibration isolation assembly compris- 
ing: a support member; a piece of equipment; said equip- 
ment having spaced apertures aligned with aperture 
formed in said support structure; said apertures in said 
support structure being enlarged; elastic tubes of a dimen- 
sion capable of folding upon itself under small compres- 
sive loads fitting within said enlarged apertures and abut- 
ting said support structure; cup-like washers engaging and 
surrounding the nonabutting ends of said tubes; screws 
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10 
15 
20 
25 
30 
passing through said washers and elastic tubes and en- 
gaging nuts formed integral with said support structure; 
and resilient folded beads formed by the compression of 
said elastic tubes between said support structure and 
said equipment and said cup-like washers and said equip- 
ment whereby said equipment is isolated from the vibra- 
tions of said support structure. 
12. A miniature vibration isolation assembly as in 
claim 11 wherein said cup-like washers engage and sur- 
round the ends of said tubes located between said equip- 
ment and support structure. 
References Cited by the Examiner 
UNITED STATES PATENTS 
214,670 4/1879 Langen _ _ _ _ _ _ _ _ _ _ _ _  248-22 X 
2,034,639 3/119136 Sau,rer _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  248-7 
2,076,034 4/1937 Lampman _ _ _ _ _ _ _ _  248-358 X 
2,091,679 8/1937 Grant _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  248-9 
2,137,480 11/1938 Dye _ _ _ _ _ _ _ _ _ _ _ _ _ _  248-15 X 
2,361,184 10/1944 Ellis _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  248-358 
2,460,586 2/1949 Keetch _ _ _ _ _ _ _ _ _ _ _ _ _  248-7 X 
2,864,573 12/11958 Olley et al. _ _ _ _ _ _ _ _ _ _ _ _  248-9 
2,975,960 3/1961 Atalla _ _ _ _ _ _ _ _ _ _ _ _ _  248-15 X 
FOREIGN PATENTS 
1,124,389 6/1956 France. 
CLAUDE A. LE ROY, Primary Examiner. 
FRANK L. ABBOTT, Examiner. 
R. P. SEITTER, Assistant Examiner. 


Miniature vibration isolator Patent

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