Hydraulic drive mechanism for leveling isolation platform

Tsutsumi, K.

English

NASA Technical Reports Server

NATIONAL AERONAUTICS AND SPACE ADMIPIISTRATION 
WASIIINGTON, D C .  20546 
REPLY TO 
ATTN OF: October 16,  1970 
TO : USI/Scien t i f ic  & Technical Information Div is ion  
At ten t ion :  M i s s  Winnie M. Morgan 
FROM: G P / O f f i c e  of A s s i s t a n t  General 
Counsel f o r  Pa ten t  Matters  
SUBJECT: Announcement of NASA-Owned 
U.S.  Pa t en t s  i n  STAR 
I n  accordance wi th  t h e  procedures contained i n  t h e  Code GP 
t o  Code U S 1  memorandum on t h i s  s u b j e c t ,  dated June 8,  1970, 
the  a t t a c h e d  NASA-owned U.S .  p a t e n t  i s  being forwarded f o r  
a b s t r a c t i n g  and announcement i n  NASA STAR. 
The fol lowing information i s  provided: 
U , S .  P a t e n t  No, : 3,318,093 
Corporate Source : Mass. I n s t i t u t e  of Technology 
Supplementary 
Corporate Source e 
NASA Pa ten t  C a s e  No,: XMS-03252 
Please note  t ha t  t h i s  p a t e n t  covers  an invent ion  made by an 
employee of a NASA c o n t r a c t o r .  Pursuant t o  Sec t ion  305(a)  of 
t h e  Nat iona l  Aeronaut ics  and Space A c t ,  t h e  name of t h e  
Adminis t ra tor  of NASA appears  on t h e  f i r s t  page of t h e  p a t e n t ;  
however, t h e  name of t h e  a c t u a l  i nven to r  (au thor )  appears  a t  
t h e  heading of Column No. 1 of t h e  S p e c i f i c a t i o n ,  fol lowing t h e  
words ' ID . wi th  respect t o  an inven t ion  of .  . . - ' I  
Gayle Parker 
Enclosure:  
Copy of Pa ten t  
https://ntrs.nasa.gov/search.jsp?R=19710001184 2020-03-17T02:27:28+00:00Z
HYDRAULIC DRIVE MECHANISM 
Filed Jan. 13, 1965 3 Sheets-Sheet 1 
30 
HYDRAULIC DRIVE MECHANISM 
Filed Jan. 13, 1965 3 Sheets-Sheet 2 
Ke n f a r CY 7s L/ f s urn ( *  
IN  VENTOR. 
AERONA lNlS 
+ION 
HYDRAULIC DRIVE MECHANISM 
F i l e d  Jan .  13, 1965 3 Sheets-Sheet 5 
K e n t a r o  T ~ u / f ~ u m / ’  
INVENTOR. 
ATTORNEYS 
. z  
nit te 
FIG. 4 is a vertical cross sectional view of the micro- 
motion jack through the axis Y-Y of FIG. 2. 
The exemplary support table B of FIG. 1 comprises two 
triangularly shaped members 3, 5, each constructed from 
5 three I-beams bolted to each other and with the smaller 
member 5 disposed in bisecting relationship with respect 
to the sides of the larger. The larger member 3 is sup- 
This invention relates to isolation platform leveling ported on three mounting plates 7, 9, and 11- Micro- 
devices and more particularly to hydraulic drive mech- motion jacks 13 and 15 are supported on each of two 
anisms therefor. corners of the table. The third corner is supported by 
An isolation platform such as is used for the support any appropriate means since level stabilization of the 
of seismographs, interferometer devices, autocouimators, table requires only two jacks. Microjacks 13, 15 in turn 
and other precision scientific instruments must not only are supported on heavy machined metal floor plates I9 
be extremely stable and level but must oftentimes include and 21, which rest Won the floor of the building- One 
a constantly level plane regardless of external environ- frequency disturbances measuring device, rests upon the 
mental disturbances. Such a mechanical provision is corner Plates 26, 2'7 on two of the corners of the larger 
particularly necessary when the accuracy of the readings triangle, as shown, and is electrically connected by wires 
on the instrument are adversely aec t ed  beyond the tal- 28 to each Of the corresponding micromotion jacks there- 
erance limits for acceptable performance. One method 20 under. A Precision instrument 3Q, or other load, rests 
for achieving a self-leveling table is to provide thereon upon mounting plate 29 disposed on the smaller triangle 
one or more disturbance-detection devices which are each n ~ m b e r  5. BY receiving a signal from a Geotilt Re- 
connected to an automatic adjustment jack which sup- corder, its respective micromotion jack may individually, 
ports the table at points beneath each detector. When Or  in combination with another jack, level the mounting 
an external disturbance displaces the table from its hori- 25 Plate in the n m ~ n e r  PreVioUSlY described. The micro- 
zontal plane, a detection device emits a signal to its motion jack, which is more clearly shown in FIG. 2, com- 
corresponding jack, which in turn raises that portion of prises a base Plate 31 having tapped recesses in each of 
the table which has been displaced from the horizontal the four corners thereof. The recesses receive threaded 
plane. legs 35, 37, and 39, the purpose of which are to provide 
Heretofore external environmental disturbances of the 30 a level b a q  for the four Corners of the jack. Main 
stray low frequency variety, such as changes in ambient housing 33 1s connected to the top surface of base 39 
atmospheric conditions, microseismic waves, and preces- by Cap ~ z W S  41, 43 (as best Seen in FIG. 4). Main 
sion of the earth's polar axis, have been difficult to housing 33 has a horizontal hollow portion 44 disposed 
detect because of their small magnitude. However, de- therein (see FIG. 3 )  which receives an internal thrust 
tection instruments have been developed which can, with 35 nut 46, which is in turn rotatably mounted in the side 
accuracy and reliability, detect these otherwise imper- wall of the housing and ha% protruding from the how- 
ceptible disturbances. One such instrument, the Geotilt ing, aa axle Portion 51 connected to main drive gear 53. 
Recorder, utilizes a liquid level vial connected to an ioni- Main drive gear 53 in turn engages motor drive gear 
zation transducer which produces a D.C. voltage propor- 55 of ~ ~ ~ o m o t o r  57 mounted O n  a side of jack 58. The 
tional to the displacement of the vial bubble. This in- 40 Servomotor is in turn electrically connected to the afore- 
strument, developed by the Instrumentation Laboratory mentioned Geotilt Recorder, or other disturbance meas- 
of the Massachusetts Institute of Technology, has meas- uring device supported on the table. 
ured microseismic waves with amplitudes on the order As best shown in FIG. 3, there is within thrust nut 46 
of .004 to .001 inch. a shaft or drive screw 59 having at the end thereof a ver- 
With the advent of improved detecting instruments, it 45 tically disposed primary bellows plate 6 1  which conforms 
became necessary to r e h e  the jacking mechanisms ac- to the cross sectional area of hollow portion 44. An ex- 
cordingly so as to enable them to accept signals and pandable primary bellows-like assembly 63 is also dis- 
execute the minute movements which the detecting instru- posed within the horizontal hollow portion 44, and is con- 
ments are capable of measuring. The subject invention, nected therein by means of recessed base member 65 
which is referred to as a micromotion jack, or hive, dis- 50 which is set within a cutout portion of the housing ad- 
closes such a device. The micromotion jack embodies jacent the protruding portion of thrust nut 46. A con- 
a new and improved hydraulic drive system having a cas- ventional O-ring 6'7 is disposed in abutting relation with 
ing design which permits no fluid leakage despite the recessed base 65 of the primary bellows assembly 43, SO 
capability of the jack to lift up to 18,000 pounds. Due as to preclude leakage of the hydraulic fluid at this point. 
to the substantial elimination of friction and backlash 55 The expandable body of primary bellows is integrally 
within the drive mechanism, the jack is capable of re- attached to base assembly 65 at one end, and at the other 
ceiving servomotor movements and transmitting them to end to the vertically disposed primary bellows plate 41. 
the load in micro distances as small as .0000(11 of an Threaded shaft 59 which extends through the primary 
inch. In addition, it may be noted that because the bellows plate may be anchored on the other side thereof 
micromotion jack is extremely light (approximately 40 ' O  by any appropriate means, for example, a set screw 
pounds) and compact (7"xT''X 7") it is Portable and clamp 69 (as best shown in FIG. 3 ) .  Additionally may be used in varied applications. Other features and there is provided (as shown in FIG. 4) a leaf spring p66 
apparent upon recessed in hollow 44, so as to prevent rotation of bellows 
a reading of the following specification and drawings 65 plate 61 when thrust nut 46 is turned. 
wherein: It is thus seen that upon reception of a signal from the FIG. 1 shows an isometric illustration of an exemplary 
support table having micromotion jacks thereunder; servomotor, there is transmitted to drive gear 53 a ro- 
FIG. 2 is an isometric-partial cutaway view of the tatkg ch, in turn, rotates thrust nut 46, caus- 
micromotion jack showing the internal mechanical ar- ing dri to travel away from recessed base 65 of 
rangement thereof; 70 the primary bellows assembly. This in turn decreases the 
FIG. 3 is a vertical cross sectional view of the micro- volume of hydraulic hollow 44 and forces fluid up through 
motion jack along the axis X-X of FIG. 2; and passageway 71. 
o Tsutsumi, Auburndale 
3, 1965, Ser. No. 425,36 
1 Claim. (CY. 66L54.5) ' 
mechanical provisions therein for maintaining itself in 15 of the aforementioned Geotilt Recorders 25, or other IOW 
become 
3,3 18,093 
AS shown in FIGS. 2 and 3, the angularly disposed fluid 
passageway 71 leads to the top portion of the main hous- 
ing where an anmlarly disposed recess 73 extends there- 
around. Attached to the top of the main housing by re- 
cessed cap screws 79, is a top bellows assembly 81 which, 
in turn, has connected thereto the aforementioned spher- 
ical cap 83, the combination of which forms a cap as- 
sembly. The top bellows assembly, in conjunction with 
the main housing, forms a second hydraulic hollow (or 
reservoir) 87 which communicates with the first hydraulic 
hollow (or reservoir) 44 by means of the aforementioned 
passageway 71. Seated within annular recess 73 of the 
main housing, and anchored therein by a bellows retainer 
89, is annular base 93 for the secondary bellows 95. The 
secondary bellows is connected to its aforementioned base 
at one end, and to top cap assembly 81 at the other end. 
Since there is a marginal radial clearance between the 
secondary bellows and the recess within which it sits, 
the secondary, and also the top bellows and cap would 
normally be subject to radially directed forces. To pre- 
clude this, however, there is provided four radial flexures 
183 disposed at 90 degree intervals around the top of the 
top bellows assembly (see FIG. 2). These flexures are 
connected to top bellows assembly 81 at one end, and 
to bellows retainer 89 at their other end, by any appro- 
priate means, such as screws 1Q5. As previously men- 
tioned, the support cap 83, which has a curved surface 
so as to transmit to the table a minimal of horizontal 
forces, is attached to the top bellows assembly 81 to there- 
by form a unitary expandable assembly. The cap is at- 
tached to the bellows assembly by recessed machine head 
screws 107. 
In FIG. 4 and also FIG. 2 there is shown a pair of 
oppositely disposed, horizontally oriented hollow portions 
109, 111, which receive identical manually adjustable 
bellows assemblies 113, 115, which are used to cause rela- 
tively large movements of cap 83 id order tb attain a 
calibrating or a starting position for it. The adjusting 
means each comprise a trim screw 121 which is disposed in 
horizohtal aperture 125 in the centers of bellows base plate 
131. Bellows base plate 131 protrudes !koa a recessed 
portion in the main housing, and is fixed in abutting posi- 
tion to retainer member 135 having a series of apertures 
therein which receive anchoring cap screws 140 that ex- 
tend into the plate. The plate and retainer are fixed to 
the housing by flange member 143. 
As previously explained with respect to FIG. 5, there 
is provided a conventional seal 147 at the side of bellows 
base 131 closest to the hydraulic fluid. Bellows IPS, as 
with each of the preceding two bellows, is connected at 
one end to its base portion, and at the other end to bel- 
lows plate 151, the cross section of which conforms to 
the cross sectional area of the hollow. The fluid in said 
hollow communicates with fluid body 44 by means of con- 
duits 153, 155 (as shown in FIG. 4). In addition to pas- 
sageway 71, fluid body 44 communicates with main fluid 
body 87 by means of vertical hole 165. The purpose of 
the vertical hole is to prevent the formation of any en- 
trained air pockets in the hydraulic system when the unit 
i s  initially filled with fluid. Thus by manual rotation of 
trim screw 121 the height of spherical cap 83 may be 
varied due to the pressure transmitted by the hydraulic 
fluid via conduits 153, 155, and 71, and vertical hole 165. 
With respect to the automatic drive portion of the jack, 
it is seen that movement of drive gear 53 rotates thrust 
nut 46, resulting in movement of bellows plate 61, as pre- 
viously explained. Because of the comparative cross sec- 
tion area of the primary bellows and the secondary bel- 
lows, rotation of thrust nut 46 through and angle of .1 
degree results in an upward motion of the secondary 
bellows of approximately .4 micro inch. Due to the use 
of the bellows structure throughout the micro drive de- 
vice, substantially all sources of friction otherwise present 
in hydraulic jacks are eliminated. Therefqre, adjust- 
ments with a high degree of precision are made possible. 
5 
10 
15 
20 
25 
30 
35 
40 
45 
50 
4 
It is to be recognized that the accuracy of the present 
micromotion jack is governed not by limitations of the 
structure of the jack itself, but more so by accurate con- 
trol of the servomotor. Therefore, if angular position of 
thrust nut 46 were controlled to within M o  of a degree, 
the motion of the spherical cap can be controlled to the 
order of .4 micro inch or better. However, normal oper- 
ational movement of the thrust nut through a 1 degree 
arc will result in a controlled motion of the cap over 
a distance of 3.6 micro inches. 
While the micromotion jack and drive mechanism have 
been disclosed only in a single embodiment, it should be 
understood that various modifications and adaptations 
thereof may be made within the spirit of the invention, 
as set forth in the claim which follows. 
Therefore, what is claimed as new and desired to be se- 
cured by Letters Patent is: 
A motor driven hydraulic mechanism for effecting 
movement of a load in response to an electrical signal 
comprising: 
(A) a drive section including a hydraulic chamber 
having first and second end walls, a hydraulic fluid in 
said chamber for transmitting energy from the motor 
to the load; 
a flexible bellows means disposed within the hy- 
draulic fluid and having a first end wall thereof 
affixed to said first end wall of said hydraulic 
chamber; 
said flexible bellows means having a thrust nut ex- 
tending therethrough and through each said f i s t  
end walls and into operative relationship with 
the motor; 
a drive screw axially aligned and threaded par- 
tially into said thrust nut, the end of said drive 
screw protruding from said thrust nut fixedly 
seoured within a second end wall of said flexi- 
ble bellows means so that rotation of said thrust 
nut by the motor causes movement of said sec- 
ond end wall along the thrust nut axis thereby 
varying the fluid volume in said lower housing 
chamber; 
(B) a power transmitter section having disposed there- 
assembly comprising: 
p for contacting the load and 
a flexible bellows assembly, said cap being affured 
to said bellows assembly, and 
a hydraulic conduit having one end communicat- 
ing with sald hydraulic chamber and the other 
end communicating with the interior of said 
flexible bellows assembly in said power trans- 
mitter section so that movement of said thrust 
nut causes correldtive movement of said load 
contacting support cap. 
eferences Cited by the Examiner 
UNITED STATES PATENTS 
2,093,604 9/1937 Gallasch _ _ _ _ _ _ _ _ _ _  60-54.5 X 
2,240,287 4/1941 Croll _ _ _ _ _ _ _ _ _ _ _ _ _ _  60-54.5 
2,380,575 7/1945 Brown __--_--______ 60-54.5
6o 2,800,055 7/1957 May _ _ _ _ _ _ _ _ _ _ _ _ _  60-54.5 X 
3,071,930 1/1963 Moulin _ _ _ _ _ _ _ _ _ _ _ _ _  60-54.5 
eferences Cited by the Apeicant 
UNITED STATES &QENTS 
55 
O5 2,065,096 '12/1936 Robinson. 
2,362,135 11/1944 James. 
2,372,610 3/1945 Spase: 
2,672,313 3/1954 Poole. 
2,717,138 9/1955 Sheehan. 
"O 2,879,928 3/1959 Lavoie et al. 
2,944,015 12/1960 Garey. 
MARTIN P. SCHWADRON, Primary Exuminer. 
35 ROBERT E. BUNEVICH, Examiner. 


Hydraulic drive mechanism Patent

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