Apparatus for operating a pressure gauge or the like

A mechanism for operating an instrument such as, for example, a gauge primarily for measuring pressure having a diaphragm the opposite faces of which are subject to a pressure differential so that the center moves in response to such differential. The diaphragm movement is transmitted to an array of bar magnets that moves in a substantially rectilinear translative movement in response to diaphragm movement. A rotary magnet spaced from the path of movement of the array of bar magnets and within the composite magnetic field produced by the array rotates as the array is translated, the angular rotation being a predetermined mathematical or empirical function of the amount of translation and built into the array. The mathematical function is achieved by proper choice of magnet dimensions and placement thereof relative to one another. Rotation of the rotor is used to drive a pointer indicator over a scale to indicate pressure. The invention resides primarily in the transductive mechanism and the novel transmission of the movement to a rotor for driving the said pointer indicator.

BACKGROUND OF THE INVENTION 
The invention is concerned principally with apparatus whose primary use is 
in instrumentation, although not necessarily so. The apparatus of the 
invention is, in effect, a transducer of a mechanical type. Motion which 
is basically translative in a substantially linear path is converted into 
motion which is rotary by such apparatus. 
The simple function stated above is one which can be performed by many 
well-known mechanisms such as, for example, a rack and pinion gear 
meshing. The invention herein, however, evolves from the application of 
the said simple function to a case where there are two requirements which 
are not readily met by the prior art. One requirement is that the 
conversion occur through a physical barrier such as a hermetically sealed 
wall and the other requirement is that the conversion occur in accordance 
with a predetermined relationship. 
The first-mentioned requirement is basically capable of being achieved by 
the use of magnets moving on opposite sides of the wall and having their 
magnetic fields linking through the wall, but the second function is 
believed not to have been achieved by any prior art known with the 
benefits and advantages of the invention as demonstrated by the 
specification which is submitted herewith. 
This invention is exemplified hereinafter by a novel pressure gauge of the 
type in which a fluid is caused to move a pressure responsive member, such 
as for example the flexible center of a suspended diaphragm, the gauge 
having means for transducing this movement into the rotation of a pointer 
indicator moving over a suitable dial that is calibrated to read pressure 
units. As will be deduced from the preliminary remarks of this background 
discussion, the invention is considered broader and applicable to any 
apparatus which can utilize the novel transductive mechanism thereof. In 
gauges and instruments, the mechanism can be used for measuring other 
parameters besides pressure. In manufacturing processes, the mechanism is 
capable of functioning as a control element in feedback systems, 
furnishing a needed error movement one way or the other relative to a norm 
pre-established for normal operating conditions. The mechanism can be used 
to record or transmit information concerning movement. Since the practical 
application of the invention has been to the construction of a pressure 
gauge, the discussion hereinafter primarily will be limited to the 
description of such gauge, but no limitations are intended thereby. As for 
the gauge itself, features are provided which are believed novel in and of 
themselves in combination with the transducing or converting mechanism and 
these will be pointed out and claimed. 
Any gauge for measuring a parameter is intended for continuous and 
automatic use to obviate the need for manual measurements and calculations 
using classical techniques. Accuracy and reliability are the principal 
ends sought and the apparatus of the invention is intended to provide 
these attributes. The invention, however, achieves other advantages which 
give characteristices that have been sought in other gauges but not always 
achieved, certainly not all in any known gauges. 
In the type of gauge described a variable parameter is represented by a 
rectilinear mechanical movement that is transduced into a rotary movement 
for the purpose of driving a pointer indicator. The particular type of 
gauge is ideally suited for conditions where the meter movement carrying 
the pointer indicator is preferred or required to be physically isolated 
from the mechanical movement that is being produced by variation of the 
parameter being measured. This would be, for example, the case where there 
are fluids in the measuring portion of the instrument which could damage 
the meter movement or impair its reliable and accurate operation. 
The invention teaches the use of a magnetic coupling to accomplish the 
isolation above mentioned, such coupling enabling a frictionless 
transmission of energy from the measuring movement to the drive for the 
pointer indicator. 
There are many known schemes for transmitting motion through magnetic 
coupling in instruments. Several examples are disclosed in U.S. Pat. Nos. 
2,745,027, 2,722,617, 2,564,676, 2,371,511 and 2,260,516. These examples 
have disadvantages which are obviated by the invention. The invention 
contemplates a small array of two or more bar magnets which moves in a 
substantially rectilinear translation relative to a single rotary magnet. 
A small movement of the array can be arranged to produce a relatively 
great movement of the rotary magnet, the spacing between the array and the 
rotary magnet being generous considering the sizes of the magnets thus 
permitting the intervention of a pressure or liquid barrier. The side by 
side location of the bar magnets and their field interference with one 
another enable the formation of a composite magnetic field which can 
cooperate with the magnetic field of the rotary magnet in order to shape 
the field as desired and thereby to control the resulting relationship 
between the rectilinear and rotary movements. In other words the function 
represented by the angular rotation of the rotary magnet for any given 
rectilinear movement of the bar magnet array can be established as 
desired. 
One important type of function that can be achieved is a linear function, 
this being useful in cases where the parameter being measured varies 
linearly. The scale over which the pointer indicator driven by the rotary 
magnet swings can thus be made with uniform divisions, enabling easy 
interpolation and extrapolation. 
Another important type of function that can be built into an instrument 
constructed according to the invention is a second order function for use 
in measuring pressures which vary as the square root. The pointer 
indicator then is arranged to move approximately logarithmically for a 
given rectilinear movement of the array, this being accomplished by 
properly dimensioning and positioning the magnets. Again the scale over 
which the pointer indicator sweeps will have substantially equal 
divisions. 
It is essential for a complete understanding and appreciation of the 
invention to comprehend the state of the art as contrasted with the 
advance which is represented by the basic concepts of the invention. 
In the prior art, the above-mentioned patents being examples, the transfer 
or conversion of movement by means of magnetic fields has been represented 
primarily by those cases in which there is a pole to pole confrontation so 
that the movement of a magnet relative to another magnet or the movment of 
a series of magnets relative to one another is accomplished by the 
magnetic forces linking pole to pole. In all such cases, so far as we are 
aware, the movement is not much different from meshing gears or the 
coupling afforded by rotating the field of a synchronous electromagnetic 
device to achieve rotation. 
In such structures as known the movement achieved and the demands upon the 
apparatus engender limitations which many instrument makers cannot accept. 
Some of these disadvantages are mentioned hereinfter, but these do not 
comprise all. 
The use of a large number of magnets to achieve a rack and pinion effect is 
not capable of being applied to the construction of most instruments. 
There is insufficient space, the weight increase cannot be tolerated, one 
and/or the other of the moving members (driving or driven) cannot 
accommodate or furnish the movement needed. 
The achievement of a relationship between the driving and the driven 
magnetic parts is not likely to or has not been achieved with a result 
that scales of instruments have to be specially calibrated and in the case 
of second order parameters must be crowded at one end and spread at the 
other. 
The gap between the magnetic parts has heretofore been too small for 
practical utilization. Even assuming that a barrier can be placed between 
these relatively moving parts, the pressures which can be accommodated in 
a given instrument are proportional to the thickness with which the 
barrier can be built. Small gaps and consequently small barriers can only 
be accommodated in low pressure instruments. 
The description of the invention which follows shows these disadvantages 
are overcome and enables the reader to appreciate that many advantages in 
addition are achieved. 
SUMMARY OF THE INVENTION 
The invention comprises apparatus such as an instrument in which there is a 
movable member responsive to change in a physical phenomenon such as 
pressure, temperature and the like, the movement of the movable member 
being substantially rectilinear. The latter rectilinear movement in turn 
is used to produce a similar rectilinear movement in an array of two or 
more relatively short bar magnets having relatively large polar area 
arranged side by side along the line of movement of the array and with a 
common pole area of each magnet defining a plane. A rotary magnet 
polarized on opposite lateral sides is disposed with its axis parallel 
with the plane but disposed at right angles to the line of movement of the 
array. 
The spacing of the rotary magnet and array are such that rectilinear 
movement of the array will rotate the rotary magnet on its axis, with a 
sufficient gap or space between the rotary magnet and array to accommodate 
a physical barrier blocking passage of fluid or transmission of pressure. 
The dimensions and positioning of the magnets relative to one another are 
such that the angular rotation of the rotary magnet is a predetermined 
function of the rectilinear movement of the array, such function being 
established upon construction of the apparatus and comprising for example 
first or second order functions. Any desired mathematical or empirical 
function can be built into the apparatus, the construction being 
characterized by a great flexibility in the capability of shaping of the 
magnetic fields through controlled interference fields. 
In the apparatus described a meter movement with an accompanying pointer 
indicator is connected to the same shaft upon which the rotary magnet 
rotates. This apparatus comprises a gauge having added features. For 
example, the location of the rotary magnet shaft relative to the array of 
magnets of the gauge is adjustable, giving zero adjustments for the gauge 
without sacrificing sensitivity. 
Other aspects of the invention will be detailed hereinafter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As previously indicated, the invention is primarily concerned with a novel 
transducer or motion converting mechanism and apparatus for utilizing the 
same. In the specification herein, this apparatus takes the form of a 
pressure gauge for measuring differential pressure or other parameters. As 
also pointed out, the invention has a much broader base, its advantages 
being usable in many environments in addition to instrumentation. 
In FIG. 1 there is illustrated in diagrammatic form the basic magnetic 
parts of a transducer or motion transferring apparatus 10 which is 
constructed and operates in accordance with the principles of the 
invention. There are two parts to the apparatus 10, these being the array 
of magnets 12 and the cylindrical magnet 14. For ease of reference, the 
array 12 may be called the "linear element" and the cylindrical magnet 14 
may be called the "rotary element" . It should be kept in mind, that the 
linear element 12 is not stationary but intended to move in a generally 
rectilinear movement which is indicated by the double headed arrow 16. The 
rotary element 14 is the driven part of the apparatus 10 and, while its 
axis remains stationary the magnet itself will rotate as indicated by the 
double headed arcuate arrow 18. The relationship between the amount of 
linear movement of the linear element 12 and the amount of angular 
movement of the rotary element 14 is in accordance with a predetermined 
law which is established during the construction of the elements, this law 
being a mathematical or near mathematical or empirical function in 
accordance with the desires of the constructor. 
In the apparatus 10, the function can be made very close to a linear one, 
that is, the amount of angular rotation of the rotary element 14 in a 
given direction is very close to being directly proportional to the amount 
of rectilinear motion of the linear element 12. This function obtains over 
a rotary movement of the rotary element 14 which is of the order of 
180.degree. in a practical example not substantially different from that 
illustrated. 
The linear element 12 of the apparatus 10 is an array of bar magnets 21, 22 
and 23 connected together side by side. The magnets are configured with 
respect to their poles in a manner which is out of the ordinary. The fact 
that they are bar magnets is of significance only in the respect that they 
are not cylindrical as in the case of the magnet which comprises the 
rotary element 14. Each bar magnet has a length which is substantially 
less than either of its lateral dimensions. The length is that dimension 
which is normally thought of in connection with conventional bar magnets, 
that is, the distance between the opposite polar ends. In this case 
however, the length is the distance from the upper polar faces 25, 26 and 
27 to their respective bottom polar faces which cannot be seen in FIG. 1. 
This assumes that all magnets 21, 22 and 23 have the same length which is 
normally the case in practical examples. The length is the dimension shown 
for the magnet 23. 
The lateral dimensions of the respective magnets 21, 22 and 23, are for 
example the longer dimensions of the lateral surfaces 30 and 32 of the 
magnet 21, for example. The polar surface 25 thus becomes a rectangle 
whose area is substantially greater than the areas of any of the lateral 
surfaces such as 30 and 32. 
The linear element 12 is formed by connecting a plurality of bar magnets 
side by side. In the case of the apparatus 10 of FIG. 1 there are three 
magnets, in the case of the apparatus 10' of FIG. 2 there are four magnets 
and in the case of the apparatus 10" of FIG. 3 there are two magnets. The 
bar magnets 21, 22 and 23 may be cemented together by any suitable 
adhesive, generally being mounted on an arm of the apparatus as will be 
described. They are arranged with the polarities of adjacent magnets 
opposed, as shown, so that any given array will present the polar faces of 
alternate poles. In FIG. 1 the element 12 shows the arrangement with the 
polarity from left to right being south, north and south. On the bottom of 
the element 12, that is, the surfaces which face towards the rotary 
element 14 the polar faces will have the polarities from left to right of 
north, south and north. Since in practically all cases the lengths of all 
of the bar magnets making up an array or linear element will be the same, 
it can be taken that the bottom polar ends of the magnets 21, 22 and 23 of 
the linear element 12 define a plane and that this plane will under normal 
circumstances be parallel with the arm which supports the element. As a 
matter of fact, the plane defined is spaced from and parallel with the 
same plane that is defined by the bottom surface of the arm to which the 
element is cemented. The polar surfaces 25, 26 and 27 will normally be 
adhered to the said bottom surface of the arm. 
The rotary element 14 is a cylindrical magnet but is not polarized like 
most conventional cylindrical magnets. Instead it is polarized on 
generally diametrically opposite lateral sides. This is shown in FIG. 1 by 
the letters N and S placed on the end face that can be seen to indicate 
that the lateral edges are oppositely polarized. For the arrangement 
illustrated, the rotary element 14 is located near the center of the 
element 12 with its axis in a plane spaced from the bottom plane defined 
by the bottom polar ends of the magnets 21, 22 and 23 and at right angles 
to the direction of movement of the linear element 12. The axis of the 
rotary element 14 is also the axis of a shaft to which the rotary element 
14 is normally attached in a practical example, and a short length of such 
shaft is shown at 34. It is clear that the shaft 34 and the double headed 
arrow 16 are at right angles with respect to one another. 
The spacing of the axis of the rotary element 14 from the plane defined by 
the bottom polar surfaces of the magnets 21, 22 and 23 takes into 
consideration the diameter of the rotary element 14 and is required to be 
sufficient to leave a gap 36 that will accommodate the barrier discussed 
above. According to the invention, this gap 36 is proportionally much 
bigger than previously possible with prior art arrangements thus 
permitting the interposition of barriers of substantial thickness to 
resist extremely high pressures. 
The apparatus 10 is of one configuration which will provide for the 
mechanical conversion of a substantially rectilinear movement (arrow 16) 
into a rotary movement (arrow 18) wherein the amount of angular movement 
of the element 14 is very closely proportional to the amount of such 
rectilinear movement of the element 12. This structure is ideal for many 
different type of measurements, such as for example liquid level and the 
like. 
The linear function response, like other types of response, is produced by 
shaping the magnetic fields of the two elements 12 and 14 and their 
relationship. This is done by proper choice of dimensions, field strength, 
gap and so on. While the proper requirements must be worked out for the 
individual cases, the basic teachings of the invention point the way and 
make experimentation minimal. The use of the short length bar magnets 
arranged side by side and having relatively large polar areas compared to 
their lateral side areas, the cylindrical magnets with its lateral edges 
polarized and the geometric relationship of these elements provide the 
basis for practically any setup. Moreover, obtaining rotary movement of 
the order of 180.degree. and more in first and second order function 
transduction is simple by means of the teachings of the invention. The 
magnetic fields of the bar magnets 21, 22 and 23 interfere with one 
another and this is used to help shape the overall field. 
By way of example, a linear apparatus using commercial magnetic materials 
(for instance, Alnico, produced by General Electric) would have three 
magnets like 21, 22 and 23, arranged side by side to provide a dimension 
in the direction of the arrow 16 of about 11/4 inches, a lateral dimension 
at right angle to the arrow 16 of about one-half inch and a length of 
magnet (between the poles) of one-eighth inch. The lateral dimensions of 
the respective magnets in the direction of the arrow 16 is not necessarily 
equal but may require adjustment. The rotary magnet element 14 is 3/8 inch 
long and 3/8 inch in diameter. The gap 36 is about 0.2 inch. The magnetic 
elements are polarized as shown. Neutral position for the element 14 is 
close to the center of the element 12. 
Before continuing with the remaining explanation of the invention, it 
should be pointed out that the dimensions and proportions control the 
interference between magnetic fields and the shape of the overall magnetic 
field and that it is this shape which gives the desired response. It is 
feasible to multiply or divide movement by this technique and to do so 
with gaps that are quite wide so that the resulting apparatus can be 
practical and useful. Modern methods of magnet manufacture and 
magnetization enable the manufacture of an element like 12 out of a single 
member with the polarization as shown. The element 14 could be polarized 
with the poles not necessarily diametrically opposite and not necessarily 
of equal geometrical configuration. 
In FIG. 2 there is illustrated an apparatus 10' which is formed of elements 
12' and 14' whose functions are respectively substantially the same as the 
elements 12 and 14 of the apparatus 10 of FIG. 1. In this apparatus, 
however, the sizes of the magnets 21' , 22' and 23' differ somewhat from 
their counterparts of FIG. 1. The end magnets 21' and 23' are smaller than 
the center magnet 22' and hence have smaller polar areas. They produce 
less interference than larger magnets would. In addition, there is a 
laterally narrower end magnet 24' at the right hand end. All the magnets 
of the element 12' have the same length (top to bottom as viewed) and they 
are assembled together. This element 12', when moved rectilinearly in the 
direction of the arrow 16' will produce a rotary movement of the rotary 
element 14' in the direction of the arrow 18' which is angularly 
proportional to the square root of the linear movement of the element 12'. 
This type of apparatus is ideally suitable for flow measurements since the 
relationship between the output of a flow transducer and the flow volume 
or velocity in the case of a typical head type flow meter is a square root 
one. The shaft 34' will rotate as the square root of the movement in 
direction 16'. The element 12' could be constructed using three magnets 
or five. As emphasized above, the criterion is the pattern or shape of the 
magnetic field and this is a matter of geometry and magnet strength. In 
the four magnet array, the proportions are derived from substantially the 
same scale as that for the apparatus 10 of FIG. 1 for a practical example. 
The practical gauge to be described is illustrated with a magnetic setup 
exactly like that of FIG. 1, but it will be assumed to have a square root 
relation with rotary element movement. This is feasible as will be 
understood from the explanation. 
FIG. 3 illustrates a simple form of apparatus 10" which is constructed from 
the element 12", this latter being formed of only two magnets 21" and 22". 
The operation and construction are the same as previously explained except 
that in this case the element 12" is made of a single magnetic member and 
the individual magnets 21" and 22" are formed only be magnetization. Thus, 
there is no physical joint between them, the dotted line 28" being an 
imaginary line. Proper shaping of the total magnetic field can be achieved 
to obtain a relationship between rectilinear movement of the element 12" 
and the rotary element 14" which follows closely some predetermined 
function or empirical plan. 
The application of the invention to a pressure gauge is detailed 
hereinafter by way of example. This embodiment of the invention is an 
excellent example because of the stringent requirements for a gauge of 
this nature. Also, there are features of the gauge which have novelty in 
and of themselves in combination with a transducing or converting 
apparatus constructed according to the invention. The setup of FIG. 1 has 
been assumed modified dimensionally to extract square root so that the 
gauge will measure differential pressure. 
The pressure gauge to be described is one in which the movement of a 
diaphragm caused by the differential of fluid pressure on the opposite 
sides thereof is translated into the movement of an indicator pointer 
traversing a scale or dial. The means for converting the rectilinear 
movement of the diaphragm to the rotary movement of the indicator pointer 
includes a magnetic coupling utilizing a linear magnetic element 
comprising an array of bar magnets arranged side by side and mechanically 
connected to be translated by movements of the diaphragm disposed in 
magnetically coupled relationship with a rotary magnetic element. 
Translation of the linear element results in rotation of the rotary 
element according to a square root function and the indicator pointer 
which is mounted on the shaft of the rotary element moves over a scale of 
equal divisions. 
By proper construction of the array of bar magnets and the adjustment or 
"shaping" of its combined field relative to that of the rotary magnet it 
is feasible to have the angular rotation of the rotary magnet and hence 
the sweeping movement of the pointer proportional to the square root of 
translation of the linear element or to have the relationship express 
other functions. This has been explaned above, but for example rotation 
can be achieved which is proportional to the linear translation of the 
magnet array. In this latter case the gauge could be utilized for the 
measurement of liquid level, for example. In the former case, the gauge 
could be used for flow measurement. 
The principles of operation of the gauge are best explained in connection 
with FIG. 4 which is a kinematic diagram thereof. 
On the left hand side of the diagram there is illustrated a diaphram 40 
which is fixedly secured to a chassis or framework. This is represented by 
the rigid connections at 42 and 44 to a symbolic fixed frame represented 
at 46. The right and left sides of the diaphragm 40 are exposed to fluids 
whose relative pressure will cause the central area of the diaphragm 40 to 
flex toward the body of fluid that has the lower pressure. In the 
construction of the gauge the arrangement will be such that the lower 
pressure fluid body will normally be on the left as shown in FIG. 1 and 
thus, when subjected to some fluid which has a higher pressure and is 
disposed on the right side of the diaphragm, the flexing movement of the 
diaphragm 40 will be to the left as indicated by arrows. 
On the right side of the diagram there is shown a resilient member in the 
form of a leaf spring 48 having an L-shaped configuration and thus 
comprising an elongate body 50 and an arm 52. The body 50 is substantially 
parallel with the diaphragm 40 and has its upper end rigidly connected at 
54 to the frame 46. A link 56 is connected between the center of the 
diaphragm 40 and the center of the body 50, these connections practially 
being fixed. The connection 58 with the diaphragm 40 is not subjected to 
any lateral moment because the flexing of the diaphragm occurs only at its 
center, but there is a slight moment at the connection 60 since the upper 
end of the body 50 will remain fixed while its lower end together with the 
arm 52 will move. The link 56 therefore has a flexible part 57 at its 
right hand end to accommodate such movement. 
The flexing movement of the center of the diaphragm 40 will be transmitted 
by way of the link 56 to the central portion of the body 50 and will exert 
a bending force upon the body 50. The axis of bending will be 
substantially the point of the adjustable fulcrum 62 whose position can be 
raised or lowered as indicated by the arrows. The higher the fulcrum 62 
the easier it is to flex the body 50. The movement of the arm 52 can thus 
be adjusted for any given flexing of the diaphragm 40 and hence can be 
calibrated for various pressure ranges. 
The flexing of the center of the diaphragm 40 to the left as indicated by 
the arrows will also cause the lower end of the body 50 to move to the 
left as indicated by the arrow on the body 50 below the connection 60. 
On the arm 52 there is disposed an array 12 of bar magnets comprising the 
linear element of apparatus 10. Like that of FIG. 1, the linear element 12 
is formed of three magnets 21, 22 and 23 arranged side by side. The 
magnets are disposed with their polarities as shown, the exact 
configuration and disposition being detailed in connection with FIG. 1. 
The practical structure has these magnets 21, 22 and 23 cemented to the 
arm 52. The operation of the gauge requires that the linear element 12 be 
translated substantially rectilinearly with the arm 52; hence under the 
circumstances mentioned above, movement will be to the left when the 
center of the diaphragm 40 moves to the left. 
According to the invention, there is a rotary element 14 polarized as shown 
and mounted on a suitable shaft 34 journalled for rotation on an axis 
normally fixed relative to the movement of the linear element 12. The 
rotary element 14 has its magnetic field coupled with the composite 
magnetic field of the array of magnets of linear element 12 and hence when 
the two fields are so coupled the magnets producing the fields tend to 
have forces applied thereto by the magnetic lines of force which seek to 
result in a balanced total field. In such a balanced field there are 
substantially no forces exerted on the magnets for moving the same. When 
an equilibrium condition is initially established with zero differential 
pressure on opposite sides of the diaphragm 40, the components of the 
gauge are adjusted so that the pointer indicator 66 that is mounted on the 
shaft 34 is aligned with the zero indication of a suitable dial intended 
to read pressure (or other quantity). When there is pressure applied to 
the diaphragm 40 in the direction of the arrows of FIG. 4 then the linear 
element 12 will move to the left and, in order to maintain the condition 
of magnetic field equilibrium the rotary element 14 will rotate in a 
counterclockwise direction indicated by the arcuate arrow of FIG. 4. The 
rotation continues until no more magnetic force is applied to the rotary 
element 14 and the coupled magnetic fields of the magnetic array of linear 
element 12 and the cylindrical magnet of the rotary element 14 are in 
balance. Obviously the pointer indicator 66 will swing in the same 
direction and the same angular extent that the rotary element 14 rotates. 
The axis of the rotary element 14 and the shaft 34 upon which the same is 
fixed is disposed spaced from the plane defined by the bottom polar 
surfaces of the array of magnets 21, 22 and 23 in FIG. 4 as in FIG. 1. As 
stated this plane is that surface of each magnet which is facing 
downwardly as viewed in FIGS. 1 and 4. The upper polar surfaces of these 
magnets, identified in FIG. 1 as 25, 26 and 27 are cemented to the bottom 
surface of the arm 52. This arrangement includes the provision of a gap 36 
between the linear element 12 and the rotary element 14. 
The gauge which will be described in some detail is of a type intended for 
use in measuring liquid levels, flow rates and the like characteristics of 
fluids. Aside from the fact that fluids may be viscous, corrosive, and 
have suspended material of a deleterious nature therein, it is not 
advisable to subject the so-called "meter movement" that includes the 
shaft 34 and its suspension to exposure by liquids. The rotary magnet 
element 14 and pointer indicator 66 are also best not immersed in any 
liquids. In order to keep the meter movement dry there is a non-magnetic 
barrier 68 in the gap 36 between the rotary element 14 including the meter 
movement on the one hand and the linear element 12 on the other hand. This 
barrier 68 prevents fluid from either of the bodies on opposite sides of 
the diaphragm 40 from entering the part of the gauge which contains the 
rotary element 14, the pointer indicator 66, the shaft 34 the suspension 
of the meter movement, etc. Obviously the pressure exerted by the fluids 
is also contained, and the barrier 68 may be termed a pressure barrier. 
Its thickness and hence the pressure that it can withstand is determined 
by the distance across the gap 36. 
From the above description one may deduce the important characteristics of 
this type of apparatus which renders it highly effective in making 
measurements where a mechanical movement which originates within a fluid 
must be transmitted to an element outside of the fluid. This can be done 
by the device of the invention because the lines of magnetic force freely 
pass through the non-magnetic pressure barrier 68 obviating the need for a 
mechanical connection between the "wet" and "dry" parts of the gauge. The 
benefits of the invention are thus advantageously felt when the invention 
is applied to a gauge which is designed to measure differential pressures 
in fluid on opposite sides of a movable pressure responsive member such as 
a diaphragm. This fact, and as well the fact that the detailed description 
hereinafter has as its subject matter such a gauge are not intended to 
limit the application of the invention to this particular environment. 
Many different types of motion produced by physical phenomena of a wide 
variety can be translated into the rotation of a pointer indicator using 
the teachings of the invention. Such apparatus may or may not require 
intervening barriers of the type mentioned as a pressure barrier 68. 
Changes in temperature, velocity, acceleration, illumination etc. can be 
measured through the use of gauges constructed in accordance with the 
principles of the invention. Where conditions are such that the invention 
provides advantages not achieved through the use of gauges normally 
utilized for the purposes, the applicable structure can be produced from 
the teachings set forth herein. 
In addition to the use of the invention in gauges, the apparatus is suited 
for use in control structures where variation from a predetermined value 
of a parameter must be detected and the information fed back to an 
operating process to correct for the change. The apparatus can also be 
used in connection with structures for recording and transmitting 
information on the variation of a parameter. In every case it is seen that 
the parameter can be one which occurs in an environment that should be 
physically insulated or isolated from the output of the responsive 
apparatus so that the information can be transmitted through a barrier by 
means of the coupling of the magnetic fields of a linear and a rotary 
element. 
Attention is now invited to FIGS. 5 through 8 which illustrated a pressure 
gauge that embodies the teachings of the invention. Where feasible, the 
same reference characters will be used to relate the illustrations with 
the subject matter of FIGS. 1 and 4. 
The gauge 70 has a housing 71 which is preferably formed of some high 
impact plastic suitably molded. Preferably this would be a thermosetting 
resin such as a polysulfane material which may be reinforced by suitable 
fillers such as glass fibers and highly resistant to corrosives while 
having the ability to withstand high pressures. Other parts of stainless 
steel where outside the magnetic fields. A panel 74 is mounted to the 
front of the housing 71 by means of the screws 76 passing through the 
panel. A suitable scale 78 is printed or otherwise mounted on the panel 
74. A cover plate 76 with a glass window 78 and bezel 80 is mounted on the 
panel 74 by screws 82 passing through the cover plate and into the panel 
74. The cover plate 76 protects the pointer indicator 66 and its mounting. 
The housing 71 has two principal exterior parts held together by bolts. The 
low pressure part is 84 shown in FIG. 6, the high pressure part 86 is 
shown at the right in FIGS. 7 and 8 and the bolts are designated generally 
88 and are suitably spaced around the parts to hold them together at the 
joint 90. Gasket or O-rings contain the pressures and fluids. The panel 74 
is shown partially broken away in FIG. 8. There are two chambers formed in 
the housing 71, a high pressure chamber 92 and a low pressure chamber 94. 
The high pressure side of the fluid source is connected to the chamber 92 
by way of the fitting 96 and the low pressure side of the fluid source is 
connected by way of the fitting 98 to the chamber 94. The fittings are 
gasketed in conventional manners. High and low pressure bleed fittings 100 
and 102 are provided at the top of the housing 71 to enable the air to be 
bled off and the chambers fully filled with the fluids. 
An internal annular ended member 104 closes off the high pressure chamber 
92 and provides means for mounting the diaphragm 40 and the linkages. The 
left hand face of the member 104 has annular configurations which are 
indicated at 106 coaxial with the diaphragm to conform thereto and provide 
back-up therefor, and the internal face of the part 84 also has such 
conforming configuration 108 for the same purpose. The diaphragm 40 is of 
highly stable elastomeric material such as Viton and circumferential edge 
is beaded as shown and clamped in position in the joint 90. This beaded 
edge serves as an O-ring. The connections 42 and 44 actually are parts of 
the same joint and comprise an annular engagement of the entire 
circumference of the diaphragm. The diaphragm is sandwiched between a 
thick disc 110 or resinous material and a thin metal disc 112, there being 
a threaded stud 114 comprising part of the connection 48 passing through 
the discs 110 and 112, the center of the diaphragm 40 having a nut 116 
thereon to secure the diaphragm in place over the passageway 118. This 
passageway 118 is the only fluid passageway between the high and low 
pressure chambers. Washers and other means are used to connect the 
assembly supporting the diaphragm 40 rigidly to the link 56. 
The link 56 has a helical spring 120 coaxially mounted thereon between an 
adjustable seat 122 and a fixed seat 124 formed in the right hand surface 
of the central member 104. The spring 120 biases the link 56 to the right 
so that fluid passing into the passageway 118 and intended to force the 
diaphragm center to move to the left must compress this spring 120. 
The right hand end of the link 56 has a block 126 adjustably secured 
thereto to which is connected a very thin highly flexible strip of high 
tensile strength metal comprising the flexible part 57 of the link 56. 
This flexible part passes through a hole 128 in the body member 48, this 
member being secured at its upper end to the central member 104. This is 
equivalent of the frame 46 referred to in FIG. 4. The flexible part 57 is 
connected to the body member 48 indirectly, being mounted on the bottom 
keeper 129 of the spring 130 whose upper end is also connected to the 
member 104. The body member 48 is in the form of a leaf spring. From the 
keeper 129 there is a right angle bent strip of metal 134 that is welded 
to the bottom end of the body member 48 and has the arm 52 as its right 
angle bent part on the bottom end thereof. The junction 60 comprises the 
connection of the upper end of the member 134, the right hand end of the 
flexible link 57 and the bottom end of the spring 130. The flexible part 
57 relieves any bending movement applied to the link 56 and the connection 
58. It decreases any chances of remenant strain in the total linkage. 
Pressure within the chamber 92 overcoming the pressure within the chamber 
94 will force the diaphragm 40 to the left, pulling the link 56 to the 
left and compressing the spring 120. The flexible part 57 will also tend 
to move to the left pulling the bottom end of the body member 48 to the 
left and also the arm 52 to the left. 
The internally threaded fulcrum 62 mounted on member 104 has its point 
engaging against the body member 48 as shown and hence the bottom of the 
body member 48 will tend to rotate about this point. The externally 
accessible screw 136 may rotate the shaft 138 to drive the fulcrum up or 
down. This enables adjustment of the range of the gauge 70 because of 
changing the effective length of the body member 48. The spring 130 exerts 
a bending force on the body member 48, which as stated, comprises a leaf 
spring. This insures contact between the body member 48 and the fulcrum 62 
at very low differential pressures. 
The apparatus 10 is incorporated into the gauge 70 as shown, the linear 
element 12 being connected to the bottom of the arm 52 and comprising the 
three magnets 21, 22 and 23. These are disposed and move within the 
chamber 92 that will normally be filled with fluid at high pressure. The 
rotary element 14 is disposed within an elongate cavity 140 that is wholly 
within one of the walls of the part 86 and has no connection with the 
chamber 92. This cavity is seen in end view in FIG. 7 and in a lengthwise 
section in FIG. 8. The gap 36 is the distance between the facing arrows in 
FIG. 7 and the barrier 68 comprises the wall between the chamber 92 and 
the elongate cavity 140. These magnets 21, 22 and 23 are sized 
differentially from those of FIG. 1 to produce a square root function. 
The rotary element 14 is mounted to a light weight shaft 34 that is 
suspended as movements for delicate instruments. This could be a taut band 
suspension if desired, but a more conventional one is shown. There is a 
jewel block 142 that is mounted in a suitable socket 144 and biased to 
move to the left as viewed in FIG. 8 by the spring 146 pressing against 
the block. The assembly is installed through an opening in the member 86 
and sealed as shown at 148. The shaft 34 has a pivot end 150 engaging a 
jewel 152 mounted in the block at the bottom of the cavity 140. Another 
pivot end 154 engages the jewel 156 at the top end, this latter jewel 156 
being accessible through the panel 74 as shown in FIG. 5. There is a 
damping stator 157 mounted on a post 158 adjustable by means of the screw 
160 to raise or lower the post and the stator 157 into closer spacing with 
respect to the damping rotor 162. The damping rotor 162 is fixed to the 
upper end of the shaft 34 as shown in FIG. 8 and it has an axially 
extending pin 164 that protrudes through a slot 166 in the panel 74. This 
pin has a fine aluminum tube telescopically engaged thereon, the tube 
comprising the pointer indicator 66. The space 161 between the stator 157 
and the rotor 162 is capillary in dimension and filled wth a viscous oil. 
Decreasing this space by the screw 160 increases capillary drag. 
The zero adjust is achieved by means of the pin 168 whose conical point 170 
enters a suitable conical recess 172 in the block 142. The pin 168 is 
threaded into the member 86 and has a screw slotted end 174 access to 
which is had at the front of the panel 74. Moving the block 142 right and 
left will change the position of the rotary element 14 with respect to the 
linear element 12 and hence cause rotation of the shaft 34 in one 
direction or the other. 
The operation of the gauge 70 is believed obvious from the description. 
There is an equalizing passage 176 between the two chambers which is 
controlled by a needle valve 178 whose slotted head 180 is accessible 
through the panel 74. Opening passageway 176 during zero adjustment 
equalizes pressure on opposite sides of diaphragm 40. 
Many structures in addition to the illustrated gauge 70 may be constructed 
using the invention and many variations in such structures can be made 
without departing from the spirit or scope of the invention as defined in 
the appended claims.