Патент USA US2412263код для вставки
DeqlO, 1946. ' H. E. HARTIG 2,412,263 CONTROL APPARATUS Filed Feb. 24, 1943 LD/ID M10 %f€ Gttorneg Patented Dec. 10, 1946 ‘2,412,263 UNITED STATES- PATENT OFFICE 2,412,263 CONTROL APPARATUS Henry E. Hal'?g, Robbinsdale, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Application February 24, 1943, Serial No. 476,907 8 Claims. 1 This invention relates to electrical networks, and especially to networks of the normally bal anced type, which are adapted for use in electri~ cal measuring or control systems. Such normally balanced networks are so con structed that two electrically separated points in the network are at the same potential when the network is balanced. When an impedance con nected in the network, sometimes termed the con (Cl. 172-239) 2 vide an improved electrical network for use in control on measuring systems. Another object of the present invention is to provide an improved electrical network of the normally balanced type, wherein the disturbing e?’ect of the distributed capacitance between var ious parts of the network and ground is main tained at a minimum. A further object is to provide such a network, which because of its low trol impedance, is varied, the changed electrical 10, capacitance to ground, is especially adapted to conditions in the network cause a difference of have its output potential ampli?ed by an elec potential to appear between the two points, which tronic ampli?er. may be termed the output terminals of the net A further object of the invention is to provide work. This difference of potential between the an electrical network including a pair of sources output terminals may be utilized to operate suit~ 15 of electrical energy and a pair of impedance able measuring or controlling apparatus. An means, and circuit means connecting the sources other variable impedance, sometimes termed the and the impedance means alternately in series in rebalancing impedance, may be connected in the ‘ a single loop circuit. network and varied simultaneously with the op— Other objects and advantages of the present eration of the measuring or controlling appara invention will become apparent from a consider tus. This rebalancing impedance is so connected ation of the accompanying speci?cation, claims, in the network that its variation by the operation and drawing, in which the single ?gure repre of the measuring or controlling apparatus re sents an electrical control or measuring system stores the network to its balanced condition, embodying my invention. thereby reducing the potential between the net 25 Referring to the drawing, there is shown a load work output terminals to zero and stopping op device I0, which is to be operated in accordance eration of the measuring or controlling apparatus. with the temperature adjacent a resistance ele In electrical control systems employing such ment H, which may be of nickel or some other networks, it is common to use a source of alter material having a high temperature coef?cient nating electrical energy to supply the network. 30 of resistance. The load device I 0 may be any The network then operates to produce at its out suitable measuring, recording, or controlling ap put terminals an alternating potential of a given phase if the control impedance varies in one sense, and of the opposite phase if the control imped ance varies in the opposite sense. Where such an alternating current network is used, the out put potential of the network may be ampli?ed by a suitable electronic ampli?er, and the out put current of the ampli?er may be utilized to operate suitable measuring or controlling appara tus in a. sense depending upon the phase of the signal supplied to the ampli?er input. A suit able rebalancing impedance device may be con nected in the network and operated concurrently with the measuring or controlling apparatus to rebalance the network. In such a network, un paratus. For example, it may be a valve con trolling the ?ow of a temperature changing ?uid to a heat exchanger located adjacent the tem perature responsive resistance l l. The load device I0 is operated by a motor 12 through a gear train schematically indicated at IS. The motor I 2 also operates, through the gear train l3,'a slider M which moves along a resist ance IS. The slider M and resistance 15 together form a rebalancing potentiometer I6. The temperature responsive resistance H, and ‘the resistance l5 of rebalancing potentiometer 16, are connected in a balanceable network H, which is constructed in accordance with the principles of the present invention. The network ll in~ balanced capacitances between the various ele cludes, in addition to the resistances II and IS, ments of the circuit and ground give rise to out a pair of transformer secondary windings 20 and of-phase potentials between the output termi 2|, a slide-wire resistance 22, a ?xed resistance nals. Ordinarily these out-of-phase potentials 50 23, and a variable resistance 24, the latter being can only be reduced by inserting capacitance ele connected in parallel with resistance l5. ments in the network to produce a capacitive bal The network ll comprises a single loop circuit ance in addition to the resistive balance which which may be traced from the upper terminal of is used for control purposes. , It is an object of the present invention to pr0~ 55 transformer secondary winding 20, through the winding 20, a conductor 25, resistances i l, 22, and 3 amazes 23, a conductor 26, winding 2|, a conductor 2?, resistances l5 and 2t in parallel, and a conductor 28 back to the upper terminal of secondary wind ing 20. ' 61. 32 is determined by the characteristics of the ampli?er 42 and the various circuit elements controlling the transfer of electrical energy be tween winding 32 and motor winding 5|. In the The transformer secondary windings 20 and CH usual system, some ?xed shift in phase will take 2| are located on the same transformer 30, which is provided with a primary winding 3| and two additional secondary windings 32 and 33. It should be noted that the secondary windings 2t place during this transfer of energy. The con— denser 513 is so proportioned and chosen so that the current ?owing through winding 52 is al ways substantially 9O electrical degrees out of and 2| are connected so that their potentials aid 10 phase with the current ?owing in winding 5|. each other in the network ll, thereby causing a Whether the current in winding 52 leads the cur circulating current to continuously ?ow around rent in winding 5|, or vice versa, depends upon the loop in that network. The impedance ele the phase of'the signal potential applied to the ments of. the network and the potentials of the input terminals of ampli?er 42. The phase of transformer secondary winding may be so chosen 15 this signal potential depends in turn upon the that this circulating current is not sumciently sense of unbalance of the network |'|. Since large to heat the resistance elements appreciably. the motor I2 is operated in one direction or the A slider 34 cooperates with resistance 22. The _ - other, depending upon whether the current in slider St is movable along the resistance 22_by winding 5| leads or legs the current in wind means of a manually movable knob 35' which 20 ing 52, it may be seen that the direction of op? carries a pointer 36 cooperating with a stationary eration of motor i2 is determined by the sense scale. Movement of slider 34 across resistance of unbalance of network I7. 22 by means of knob 35 adjusts the control point Operation of the system. In other words, the position of slider 36 on resistance 22 determines the par Consider the potential distribution conditions ticular value of resistance H at which the net existing in the network i'i during a half cycle work I‘! is balanced, for any given position of when the lower terminals of transformer wind the rebalancing slider It and load device it). ings 2D and 2| are positive with respect to their Slider 31% is connected through a conductor 37 to upper terminals. At such a time, the current ground at 38. ' 30 ?ow around the loop circuit is in a clockwise The sliders M and 34 serve as the output ter~ direction, as viewed in the drawing. Starting minals of the network ll. ‘Slider Ill is connected from the upper terminal of transformer sec through a conductor 40 to an input terminal ondary winding 20, and following around the All of an electronic ampli?er generally indicated loop circuit in a clockwise direction, it may be at 42. The ampli?er 62 may be of any suitable 35 seen that a potential rise takes place in the wind type. For example, it may be an ampli?er of ing 20, followed by a series of potential drops ' the type shown in the co-pending application across resistances ||, 22, and 23, another poten of Albert P. Upton, Serial No. 437,561, ?led April tial rise across secondary winding 2|, and an 3, 1942. The ampli?er 132 is provided with a sec other drop across the resistances l5 and 24 in ond input terminal 433, which is connected to 40 parallel, back to the upper terminal of secondary ground at £343, and through ground connection 38 ‘Winding 2c. Taking ground potential, which is and conductor 31 to slider 3%. The ampli?er 62 that of slider body 3%, as a reference, it may be is provided with power supply terminals 45, t6, seen from the foregoing that points on the re and Ill, which are connected to the opposite ter sistance 22 to the right of slider 3d are negative minals and a center tap, respectively, of trans 45 with respect to ground, while parts to the left former secondary winding 32. The ampli?er 62 of slider 36 are positive with respect to ground. is also provided with a pair of output terminals Furthermore, since by Kirchhoff’s1aw,_the sum of 48 and 49.‘ the potential rises and drops around the loop The motor i2 is of the split phase type, and is circuit must be zero, it may be seen that there provided with a pair of ?eld windings 5i and 52 are four points on the loop circuit which are at ' which are displaced from each other 90 electrical ground potential. One of these points is of degrees in space. A condenser 53 is connected in course the slider 36, another is located on resist parallel with motor winding 5|. The winding ance | 5, and the other two at some point in each 52 is connected in a series circuit which includes of the transformer windings 20 and 2|. If the the transformer secondary winding 33 and a con network H is balanced, the point at ground po denser 54. tential on resistance I5 is that point engaged by The motor winding 52 is supplied with alter slider iii. If the sum of the resistances | I, 22, nating current whose phase with respect to the and 23 equals the equivalent resistance of the alternating potential supplied by secondary parallel resistances i5 and 24, the points of 60 winding 33 is ?xed by the condenser 56. The ground potential on windings 2|] and 2| will be motor winding 5| and its parallel condenser 53 the center points of those windings. If the sum are connected across ampli?er output terminals of the resistances | i, 22, and 23 is not equal to 88 and 49. As explained in detail in the co the equivalent resistance of the parallel resist pending Upton application, Serial No. 437,561, ances I5 and 24, the points on the windings 20 previously referred to, the ampli?er 62 operates and 2| which are at ground potential will be in response to the application of an alternating displaced from the center points of those wind signal potential to its input terminals to supply ings in one direction or the other, depending the motor winding 5| with an alternating cur upon which group of resistances is the largest. rent of a given phase or the opposite phase, de Furthermore, it may be pointed out that since pending upon the phase of the alternating po the average potential to ground of all points along tential applied to the input terminals iii and any one half of the loop circuit is zero, under 63. The phase of the alternating current sup balanced conditions, the effect of distributed ca plied to winding 5| with respect to the alternat pacitance in the network H is minimized. ing potential supplied by transformer winding 75 Consider now the conditions obtained in ‘the 2,412,263 network I7 if the resistance II increases, such as would occur upon an increase in the tempera ture adjacent it. Such an increase in resistance -II increases the sum of the potential drops on the left hand side of the loop between sliders 34 and I4, above the sum of the potential drop along the right hand side of the loop between the sliders. The point of ground potential on 6 essary to cause movement of the valve from its fully closed to its fully open position. While I have shown and described a preferred embodiment of my invention, other modi?cations thereof will readily occur to those skilled in the art, and I therefore wish my invention to be lim ited only by the appended claims. I claim as my invention: resistance I5 is thereby shifted to the left along 1. Temperature control apparatus, comprising resistance I5, making slider I4 positive with re 10 in combination, a pair of sources of electrical spect to ground. In a similar manner, if the re energy, a pair of impedance means, means con sistance H decreases, the potential of slider I4 necting said sources and said impedance means alternately in a series circuit, one of said imped ance means comprising, in series, a temperature potential of slider I4 were made under the as sumption‘that only the conditions existing when 15 responsive resistance element and a ?xed resist ance element, the other of said impedance means the lower terminals of secondary windings 20 and comprising a potentiometer resistance element, 2| were positive were being considered. Consid said potentiometer resistance element having a ering the conditions existing during an alternate contact slidable with respect thereto to complete half cycle, when the transfomer secondary wind ings 20 and 2| have their upper terminals positive 20 an electrical connection with any of a plurality of spaced points thereon, temperature control with respect to their lower terminals, it is be means, electrical motor means for driving said lieved to be readily apparent that the opposite temperature control means and said slidable con conditions as to the potential of slider I4 exist. tact, and potential responsive means for control Therefore, when alternating current is supplied ling said motor means connected between said to the network I‘! from windings 20 and 2|, the contact and a point on said other impedance potential difference between sliders I4 and 34 is means intermediate said temperature responsive zero when the network I1 is balanced. When resistance element and said ?xed resistance ele the resistance II increases above its normal value, ment. > a potential of the same phase as that existing 2. Control apparatus, comprising in combina 30 between the lower and upper terminals of sec tion, a pair of sources of electrical energy, a pair ondary winding 20, respectively, appears between of impedance means, means connecting said sliders I4 and 34, and is impressed upon the sources and said impedance means alter input terminals 4I and 43 of ampli?er 42. Sim nately in said series circuit, an electronic ilarly, when the resistance II decreases, an al ternating signal of a phase opposite to that exist 35 ampli?er having input terminals and out put terminals, a connection between an inter ing at the terminals of secondary winding 20 is mediate point on one of said impedance means impressed on the input terminals of ampli?er 42. and one of said ampli?er input terminals, con Therefore, it may be seen that the motor I2 is nections between ground and a normally equipo rotated in one direction when the resistance of tential point on the other of said impedance element I I increases from a predetermined value, means and between ground and the other of said and is rotated in the opposite direction when the input terminals, control means connected to said resistance of element II decreases from that ampli?er output terminals, and means for vary value. If the load device I0 is controlling the ing at least a portion of one of said impedance supply of a heating ?uid to a space in which re 45 means to produce an unbalance potential between sistance II is located, the direction of rotation said points. of motor I2 is so chosen that the supply of heat 3. A balanceable electrical network, comprising ing ?uid is increased when resistance element in combination, a pair of sources of electrical II decreases, and the supply of heating ?uid is energy, a pair of impedance means, means con decreased when the resistance of element II in 50 necting said sources and said impedance means creases. alternately in a series circuit, one of said im It is believed that the functioning of the slider pedance means comprising a potentiometer im 34 as a control point adjuster for the system will pedance element having a contact slidable with be readily understood from the foregoing with respect thereto to complete an electrical con out further explanation. The resistance 24 determines the total resist 55 nection with any of a plurality of spaced points thereon, potential responsive means connected ance between the terminals of the parallel group between said contact and a normally equipo consisting of resistances I5 and 24. It therefore tential point on the other of said impedance determines the total potential drop across this is made negative with respect to ground. The foregoing statements with'respect to the parallel group. Furthermore, its setting deter means, means for varying at least a portion of one mines the resistance drop per unit length of the 50 of said impedance means to produce an unbalance potential across said potential responsive means, slider wire resistance I5. Therefore, when a and means operated by said potential responsive change in the resistance element II causes a means for driving said contact along its associated given change in the potential of slider I4, the set impedance element so as to reduce said unbalance ting of resistance 24 determines the distance 65 potential substantially to zero. along resistance I5 through which the slider I4 Ll. A balanceable electrical network, comprising must be driven by the motor I2 in order to re in combination, a pair of sources of electrical balance the network IT. The resistance 24 there energy, a pair of impedance means, means con fore determines the width of the range of tem necting said sources and said impedance means peratures adjacent resistance II which causes slider I4 to be moved from one end of its travel 70 alternately in a series circuit, one of said imped ance means comprising a potentiometer im to the other. If the load device III is a valve pedance element having a contact slidable with controlling a supply of heating ?uid, the setting respect thereto to complete an electrical con of resistance 24 therefore determines the total nection with any of a plurality of spaced points change in temperature adjacent resistance I I nec 75 thereon, potential responsive means connected be 2,412,283 lb) tween said contact and a normally equipotential point on the other of said impedance means, means for varying at least a portion of one of said impedance means to produce an unbalance potential across said potential‘ responsive means, means operated by said. potential responsive means for driving said contact along its associated impedance element so as to reduce said unbalance potential substantially to zero, and a variable impedance device connected in parallel with said 10 ating said control device and means connecting said potential responsive means between said ‘taps on said pair if impedance means, said con necting means including means for varying the ratio between the impedances of the portions of one of said impedance members on either side of said tap. '7. A balanceable electric network, comprising in combination, a pair of sources of electrical energy, a pair of impedance means each includ potentiometer impedance element to control the potential di?erence per unit length of said ele ing end terminals and an intermediate tap, means connecting said sources and said impedance ment and hence the distance moved by said con means alternately in a single series circuit, poten tact in response to a given operation of said tial responsive means, means connecting said impedance varying means. 15 potential responsive means between the taps on 5. A balanceable electrical network, comprising said impedance means, said taps being normally in combination, a pair of sources of electrical at the same potential, means for varying the energy, a pair of impedance means, means con the ratio between the impedances of the portions necting said sources and said impedance means of one of said impedance means on either side alternately in a series circuit, an electronic am 20 of said tap to produce an unbalance potential be pli?er having a pair of input terminals and a pair of output terminals, means connecting each of said input terminals to a point on one of said impedance means, said points being of the same tween said taps, and means operated by said potential responsive means for varying the ratio between the impedances of the portions of the other of said impedance means on opposite sides potential when said bridge is balanced, means 25 of the intermediate tap to restore a potential for varying at least a portion of one of said im difference between said taps to zero, thereby re pedance means to produce an unbalance potential balancing said network. between said points, and means connected to said 8. An electrical network for producing an alter ampli?er output terminals for varying a different nating potential variable in phase and magnitude _ portion of one of said impedance means to re ~30 in accordance with the departure of a variable store the potential between said points to zero, condition from a predetermined value compris thereby rebalancing said network. _ ing in combination a pair of transformer second 6. Control apparatus, comprising in combina ary windings, a pair of impedance means each tion, a pair of transformer secondary windings, a including end terminals and an intermediate pair of impedance means each including end tap, means connecting said sources and said im terminals and an intermediate tap, a single cir pedance means alternately in a series circuit, out cuit connecting said windings and said impedance put terminals for said network connected to said means in series, said windings being connected intermediate taps, and means responsive to said into said circuit to aid each other, each said condition for varying the ratio between the por secondary winding being connected to one ter 40 tions of one of said impedance means lying on minal of each of said impedance means, a con trol device, potential responsive means for oper opposite sides of said intermediate tap. HENRY E. HAR'I‘IG.