Патент USA US2117670код для вставки
May 17, 1938. M. FfKETAY ET AI. 2,117,670 _ SALINITY INDICATOR Filed sem.` 1o, l195e A-C-UNF. m l. Patented May 17, 1938 N 2,117,670 ` UNITED-STATES . PATENT oFFlcE j 2,117,670 ~ SALINITY INDICATOR Morris Fred Ketay,~ Brooklyn, N. Y., and Joel Darwin Peterson, Roselle, N. J., assignors to Bendix Aviation Corporation, South Bend, Ind., a. corporation of Delaware Application September 10, 1936, Serial No. 100,216 ‘5 Claims. (Cl. 175-183) Fig. 5 is a vector diagram similar to Fig. 4 This invention'relates to devices for electrically measuring and indicating the saline content of l but illustrating the conditions existing when the iiuids, and more particularly to the electrical cir cuits employed in salinity indicators of this type. One of the objects of' the invention is to pro Ui vide an improved salinity indicating device in which is embodied a novel electric circuit for ef fecting movement of that element of the device the position of which serves as an indication of 10 the degree of salinity of the ñuid being tested. Another object is to provide a new and im proved electrical circuit for use in salinity indi cators in which a modified form of Wheatstone bridge/is utilized. 15 A further object is to provide a salinity indi cator of the character referred to in which is included improved means for compensating for variations in the temperature of the fluid being tested. 20 ` . ' Still another object is to provide an electrical - ciflc Acircuit arrangement has been disclosed and illustrated in the accompanying drawing, it is to be expressly understood that this drawing is 5 . that required to balance the bridge circuit. As shown somewhat schematically and -diagrammatically in Figs. 1, 2 and 3, the salinity measuring and indicating device of the present invention comprises an electrical meter so com bined with a modiñed form of bridge circuit and a salinity cell,as to give an accurate indication of the degree of salinity of the ñuid being tested in the cell. Since the resistance to current iiow through the salinity cell varies inversely with the temperature of the ñuid as well as with its salin ity, the vindicator circuit also includes means for compensating for variations in the ñuid tem The meter or indicating portion of the device consists of movable and fixed elements mounted 20 in a suitable casing 9 in such a manner that the position of the movable element at any instant constitutes a clear indication of the salinity of the fluid being tested. ' As illustrated, the mov able element of the meter -comprises a pair of circular coils of wire C1 and C2 mounted with be construed as a definition oi’- the limits of the their planes at right angles to one another and having a common diameter, indicated at I0, which serves as their axis of rotation. Coplanar invention, reference being had for this latter with coil C1, yand ñxed with respect thereto so purpose to the appended claims. . as to rotate therewith about axis IIJ, is a suit- v In the drawing, wherein like `reference charac ters indicate like elements throughout the sev `eral views: ` Fig. 1 is a view of the face of the meter or indicator of a salinity measuring and indicating device embodying the present invention with the fixed and movable coils of the electrical circuit indicated schematically, the positions of the mov able coils and indicating pointer corresponding to a fluid of zero salinity; 45 _ tion and of greater accuracy than similar instru for purposes of illustration only and is not to> 40 _ ' Fig. 6 is another vector diagram corresponding to a fluid the salinity of which is greater than perature. These and other objects of the invention will appear more fully upon consideration of the de 25 tailed description of the embodiment of the in vention which follows. Although only one spe-- 35 the bridge circuit; and salinity indicating device of improved construc ments hitherto known to the art. " 30 ñuid is (a) of relatively slight salinity and (b) of sufficient salinity to just effect a balancing of Fig. 2 is a diagram of the electrical circuit of a salinity indicator constructed in accordance with the invention; y , Fig. 3 is a schematic rearrangement of the cir cuit diagram of Fig. 2 more clearly illustrating 50 the modified bridge circuit utilized by the present invention; Fig. 4 isa vector diagram of the electromag netic ñelds produced by the fixed and movable coils oi’ the indicator when the salinity of the fluid being tested is zero; able indicating element such as a pointer II adapted to travel` over a scale I2 calibrated in terms of salinity. The fixed or iìeld element of the meter consists of a, pair of field coils I3 and Il, of somewhat larger diameter than movable coils C1 and C2, which are ñxedly mounted ad jacent themovable coils on opposite sides of axis IIJ with their planes vertical and parallel to one another. 'I'he magnetic fields produced by coils I3 and I4 arefcoaxial and extend at right angles to axis I0. As indicated in Fig. 2, ñeld coils I3 .. and III are connected in series across the termi nals-of the indicator, said terminals in turn be ing adapted for connection to any suitable source - of alternating current. Movable coils C1 and C2 are electrically connected to the electric circuit of the indicator next to be described _by three hair springs (not shown) of negligible- torque, two of the springs being connected to the ends of the coils while the third spring is connected to the junction therebetween. The relative po 2,117,670 sitions of these three springs are shown in the circuit diagram of Fig. 2 at the points marked I5, I6 and Il. » 'I'he elements of the indicator thus far de scribed are combined and electrically connected with a salinity cell and a novel testing -circuit in the manner illustrated in Fig.- 2. As shown there in, the cell comprises a suitable container I 8 for the ñuid to be tested and a pair of electrodes I9 10 and 20 which are mechanically held in ñxed and parallel spaced relation and completely immersed in the ñuid in container I8. If desired, the salin ity cell may be mounted in or secured to the in dicator ‘casing 9 and suitable connections pro 15 vided for enabling the fluid to be tested to flow to and from the container I8. One of the electrodes ì of the cell, electrode I9 in the example illustrated, is connected .to the same terminal of the indicator as :field coil I 3 while the other electrode 20 is con 20 nected to the opposite terminal through two par hence vary the current ñowing through both coils Ci and C2, the relative amounts of current ñow ing in coils C1 and C2 remain the same With the result that the resultant iield R of said coils, al though altered in magnitude, will not be changed El in direction and the pointer vII will remain in the position shown in Fig. 1. This ñxes the zero posi tion of the pointer. - If it now be assumed that the iluid being tested is slightly saline, the resistance to the passage of current between electrodes I9 and 20 is reduced to a finite value. Under these conditions, the cur rent flowing in the circuit passes part through the leg of the bridge containing the resistance T and part through the leg represented by the re sistance B, thus tending to balance the bridge and reduce the current through the coil C2. Due to the consequent reduction in the current passing through the resistance T, the current flow through the coil C1 will be slightly increased. The fields of the coils Ci and Cz will then b'e of the allel paths, one path including the fixed resistance R1 and the other comprising movable coils Cz magnitude and direction represented by the vec- ‘ and C1 (in series) and a fixed resistance R3 which serves to limit the current through the coils in tors F1 and F2 of Fig. 5, with a resultant field rep 25 the event of a short circuit of the electrodes. resented by the Vector R. Since the resultant Connected in parallel with the cell and coil C2 is . field will again tend to align itself with the main '.25 field of the ñxed coils I3 and I4, the coils Ci and a calibrated variable resistance 'l' which is adapt C2 will be rotated through the angle a, this rota ed to be manually adjusted to correspond to the tion turn moving the pointer II through an temperature of the ñuid being tested in the cell. equalinangle in a clockwise direction. Another fixed resistance R2 may be shunted across If, at this time, the temperature of the ñuid in coil C1 and resistance R3 in order to ensure a proper division of current ilow between the coils the container I8 should increase, there would C1 and C2. >As is best illustrated by Fig. 3, the result a ldecrease in the cell resistance B and an increase in the amount of current flowing through electrical circuit just described is in fact a modl 35 fied form of Wheatstone bridge with the resist- the corresponding leg of the bridge circuit. How ance B of the iluid in the cell and temperature ever, this temperature change may be manually 3,5 compensated for by decreasing the variable re compensating resistance T constituting the par allel variable legs of the bridge and the coil C2 sistance T suil'iciently to result in the same un balance of the bridge as before, and therefore the functioning as the bridge wire. same ratio of field strengths of the coils Ci and C2. 40 Referring now to Fig. 4, let it be assumed that If the salinity of the ñuid were such that its 40 the salinity of the ñuid under test is zero-that resistance acted to balance the bridge, the cur is, the iiuid contains no salt; the resistance of the rent in coil C2 would be zero and the resultant fluid tothe passage of alternating current then ñeld of the coils Ci and Cz would be the ñeld of approaches an inñnite value. Under these cir 45 cumstances, if the terminals of the indicator be the coil Ci. In this case, the coils C1 and C2 would be rotated from their zero positions through connected to a source of alternating current, the entire current will pass through that leg of the the angle b indicated in Fig. 5 to bring the ñeld Fi of coil C1 into alignment with the main field, bridge circuit containing the temperature com the pointer II turning through a like angle from pensating resistance T and then divide between the position shown in Fig. 1. Here again any 50 the coils C1 and C2. If at any instant the mag reduction in fluid resistance due to an increase 50 netic ñelds of lfixed coils I3 and I4 are as rep in temperature would be compensated for by re resented by the vectors F1a and F14, the circuit is ` ducing the resistance T sufficiently to rebalance such that the ñelds of coils C1 and C2 will be rep ‘ the bridge. resented bythe vectors F1 and F2, as shown. The ’ If the salinity of the fluid should increase be 55 resultant of the latter two perpendicularly di that suflicient to elfect a balancing of the rected ñelds will be a field represented by the . yond bridge, the bridge would again be unbalanced, 55 vector R which will attempt to align itself with the main field F13, F14- of the fixed coils I3 and but in a direction opposite to that previously de I4. Inasmuch as the coils'Ci and C2 are free to ' scribed, and the field of the coil C2 would be re versed. Under these conditions, the positions of_ rotate about the axis I0, the tendency to align ment of the resultant and main ñelds will place the 'vectors representing the iields of the several the coils C1 and C2 in the positions indicated coils, after alignment of the resultant ñeld with which, in turn, will carry the pointer II over the that of the fixed coils, would be as shown in Fig. scale I2 to the position shown in Fig. 1. When 6. In this case, the pointer II will swing even 65 the direction of the current ñow is opposite to further in a clockwise direction, as viewed in Fig. that just considered, the directions of the vectors ' 1, onto the right-hand portion of the scale I2. 65 of Fig. 4 will be reversed; however, since all of _Anyvreduction in circuit resistance with an in the ñelds of the circuit are reversed, the pointer crease of 'temperature will still be compensated will remain in the same position. Furthermore, ' for by reducing the resistance T to produce the so long as the salinity of the fluid remains zero, same degree of unbalance of the bridge as before and thereby maintain the correct pointer posi any change in temperature of the fluid or any tion. variation in the resistance T will likewise have no 'I'here is thus provided by the present invention eiîect upon thel position of the pointer. While a change in the resistance T will vary the total an improved salinity measuring and indicating amount of current passing therethrough and device embodying a novel electrical circuit for producing an accurate indicatlonof the salinity 2,117,670 3 and an indicating member iixed with respect to said movable coils for rotation therewith about of the iiuid under test, the said circuit consti tuting a modiñed form of Wheatstone bridge and including as one of the variable legs thereof a said axis, a variable resistance, and a ñxed re manually adjustable resistance which serves to compensate for variations in the fluid tempera ture. Although only one particular form of in the form of a Wheatstone bridge with the elec dicator has been speciñcally disclosed, it will be obvious that the invention is not limited there to but is capable of a variety of mechanical em 10 bodiments. Various changes, which will now sug gest themselves to those skilled in the art, may be made in the forni, details of `construction and arrangement of the elements Without departing from the spirit of the invention. Reference is, sistance, said electrodes, movable coils andre sistances being electrically connected together in trodes and variable resistance lying in parallel legs of the bridge and one of said movable coils constituting the bridge Wire, the other movable coil and ?lxed resistance comprising the other 10 two legs of the bridge, said variable resistance being calibrated in terms of the temperature of the iluid being tested and manually adjustable to compensate for variations in said temperature. 4. In a salinity measuring and indicating de 15 therefore, to be had to the appended claims for _ vice, a pair of spaced electrodes adapted to‘be 15 a deiinition of the limits of the invention. What is claimed is: 1. In a. salinity measuring and indicating de immersed in the fluid the salinity of which is to be determined, a meter for indicating the cur vice, a pair of spaced electrodes adapted to be rent flow between said electrodes including a pair 20 of parallel ñxed coils arranged on a common 20 immersed in the fluid the salinity of which is to axis and adapted to produce a main energetic be determined, a meter for indicating the cur rent flow between said electrodes, comprising field, a pair of movable coils mounted in said mutually interacting iixed and movable coils, a field with their planes at right angles to one an variable resistance calibrated in terms of the other and having a common diameter about vwhich they are free to rotate as an axis and an 25 25 temperature of the fluid being tested and man ually adjustable to compensate for variations in said temperature and a iixed resistance; said lelectrodes, meter, variable resistance and fixed resistance being electrically connected together indicating pointer iixed with respect to said mov able coils for rotation therewith about said axis, a variable resistance, and a ñxed resistance, said electrodes, movable coils and resistances b_eing electrically connected together in the form of a 30 Wheatstone bridge with the electrodes and var iable resistance lying in parallel legs of the bridge tuting the bridge wire across one diagonal of the and one of said movable coils constituting the bridge, a second coil connected across the other . bridge wire, the other movable coil and ñxed resistance comprising the other two legs of the 35 ` diagonal of the bridge, and a third coil compris bridge. ing a third leg of the bridge. 5. In a, salinity measuring and indicating de 2. In a salinity measuring and indicating de vice, a pair of spaced electrodes adapted to be vice, a pair of spaced electrodes adapted to be immersed in the iiuid the salinity of which is to be immersed in the fluid the salinity of which is to . determined, a meter for indicating the current 40 = be determined, a meter for indicating the current flow between said electrodes including a pair of flow between said electrodes including a plurality parallel fixed coils arranged on a common axis of iixed coils adapted to produce a main mag and adapted to produce a main magnetic field, a netic field, a pair of movable coils mounted in f pair of movable. coils mounted ,inl said ñeld with said iield and having a common diameter about their planes at right angles to one another and 45 which they are free to rotate as an axis and an indicating member ñxed with respect to said having a common diameter about >which they in the form of a. Wheatstone bridge with the electrodes and variable resistance lying in par allel legs of the bridge, one of said coils consti movable coils for rotation therewith about said are free to rotate as an axis and an indicating pointer ñxed with respect to said movable coils for rotation therewith about said‘axis, a variable ing electrically connected together in the form of resistance, and three fixed resistances, said elec trodes, movable coils and resistances being elec a Wheatstone bridge with the electrodes and var iable resistance lying in parallel legs of the bridge trically connected together in the form of a and one of said movable coils constituting the Wheatstone bridge with the electrodes and vari bridge wire, the other movable coil and fixed re -able resistance forming two of the parallel legs 55 of the bridge and one of said movable coils con sistance comprising the other two legs of the stituting the bridge wire, the other movabley coil being connected in series with one of the said 3. In a salinity measuring and indicating de vice, a pair oi' spaced electrodes adapted to be fixed ‘resistances to form the thirdv leg of the immersed in the fluid the salinity of which is to bridge and the second fixed resistance completing the bridge, the third iixed resistance` being shunt be determined, a meter for indicating the cur rent `iiow between said electrodes including a ed across said third leg of the bridge to ensure plurality of fixed coils adapted to produce a main a proper division of current betweenl said movable magnetic field, a pair of movable coils mounted coils. ‘ MORRIS FRED KE'I'AY. axis, a variable resistance, and a iixed resistance said electrodes, movable coils and'resistances be bridge. ` I „ in said ñeld and having `a common diameter about which they are `fi.'i:ee¿tiyrgitate"as an`axis. JOEL DABWIN‘PE‘I'ERSON.