US2535430A - Control instrument - Google Patents

Description

Dec. 26, 1950 G. w. KUNTNY CONTROL INSTRUMENT 3 Sheets-Sheet 1 Filed D60. 20, 1945 Y .N Wm M U K E. VW on 0 G E R G ATTORNEY.

Dec. 26, 1950 G. w. KUNTNY CONTROL INSTRUMENT 5 Sheets-Sheet 3 Filed Dec. 20, 1945 FIG. 5

FIG. 5

INVENTOR. GREGOR W- KUNTNY M y W W.

ATTORNEY.

Patented Dec. 26, 1950 UNITED STATES PATENT OFFICE 2,535,430 oONiRoL INSTRUMENT Gregor W; Kiintny, Philadelphia, Pa., assi'gnor,

by m'esn'e assi nments, to Minneapolis-Honeywell Regulator Company, Minneapolis; Minn., a corporation of Delaware Application ljec'einbr 20, 1945'. Serial Nb. 636,219

laimsi (Cl;

The present invention relates tocontrol in; struments and more particularly a mercury switch control mechanism that is adaptable for use with a, potentiometer type of instrument.

It is an object of the invention to provide a control instrument of a type that may be readily adjusted to control the condition being measured to any value within the range of the instrument. It is a further object of the invention to provide a relatively sensitive control system, or; one in which the control switch can be thrown from one position to another by a movement of a condition responsive member through a rela} tively small pcrcentage of the instrument scale.

It is a further object of the inventiontdproride a mercury switch control mechanism in which the switch is mounted on a carriage that is to be moved through an elongated toja position proportional tothe value at which the condition under control is to be maintained. Another part that is moved to positions correspond ing to the changing value of the condition cooperates with the switch to operate it in onle direction or the other as the condition varies above or below the control point. e H V It is a further object of the invention to pro videa means to hold positively the controls witch the position to which it has been adjusted. This means comprises latch fingers cooperating with the switch support. The fingers are au: tomatically released as the switch operating part moves into position when the switch has been operated. In another form of the invention the same means which serves to operate the control switch holds the switch in its adjusted position.

The various features of novelty which chareterize-this invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention," however, its advantages and specific objects obtained with its use; reference should behad to the accompanying drawings and descriptive matter in which is 11*- lustratrd and described a' preferred embodiment of the invention.

In the drawings: Figure 1 is a wiring diagram of a potentiometer circuit; Figure 2 is a perspective view of one form" of the invention, I, Figure 3 is a front view o f a' different form of invention; r r Figure 4' isa view taken on line 4 4 of Fig are 3,

2 Figure 5 is a view of a still difierent embodiment of the invention, and

figure 6 is a detailed view of a portion of Fig- Referring first to Figure 1 there is shown a wiring diagram of a potentiometer circuit. In an instrument of this type there is provided a slid'ewir'e l across which a potential is placed by a battery 2. A por'tionof this potential is opposed by the E. M. F. developed by a thermocouple 3; and to this end the thermocouple is connected in the potentiometer circuit by means of a collector 4 thatis attached to one of the th rmocouple terminals. This collector is'con} nested electrically with the slidewire l by means or a movable contact 5. The other thermocouple terminal is connected to the circuit through a switch 6 and an amplifier I. When the contact 5 is so positioned along theslidewire l and collector l that there is no' current flow in the eir cjuit, the instrument is in balance. If, however, the thrrmocouple should be subjected to a change in temperature, the voltage produced thereby weuld change and a current flow would take place through the potentiometer circuit. This current' fio w is detected and amplified by the amplifier 7 to produce an energization of a rebal'ancing' motor 8 in a, direction depending upon the current flow in the circuit. The motor is mechanically connected to contact 5 to move this contact along slidewire I in such a direction that the thermocouple voltageis exactly opposed bythe vvoltage drop across the slidewire When contact 5 reaches this point along the slidewire I, current will cease to flow in the circuit and the motor will again be deenergized so that the contact will remain still until a further change in thermocouple voltage takes place. At times it is necessary to r'ecalibrate or standardize .the potentiometer circuit. This is accomplished by moving a contact 9 of switch 6 to the right to disconnect the' thermocouple from the circuit and to connect a" standard cell H in its place. This standard cell is connected in the circuit and a suitable resistance 12 is simultaneously con nec't'ed in the circuit around the amplifier 7. The standard cell produces a givenvoltage drop across a portion of" thefpotentio'meter circuit so that i f'lthis' voltage' is not exactly opposed bythe volt age of the battery' 2, a resistance It may be ad; mer e in suitable manner until the voltages" are eq al. Thereafter the contact sf is'rnoved to the" to again connect the therm ocouple in the circuit.- For further details of the potentiometer circuit and the amplifier, attention is called to the copending application of Walter P. Wills, Serial No. 421,173, filed December 1, 1941, now Patent 2,423,540 issued July 8, 1947.

In Figure 2 there is shown one embodiment of the invention in which a mercury switch support is moved to a position corresponding to the temperature which it is desired to maintain, and in which a part movable by the motor 8 as it adjusts the slidewire is moved to adjust the switch mechanism.

There is provided a pair of supports l4 and 15 which may be attached to any suitable part of the instrument. These supports are joined by a channel member If; and a shaft l! which serve to mount and guide the various movable parts of the switch mechanism. lviounted for movement along the channel I6 is a control table it. This table is generally U-shaped and is provided along the cross part of the U with spring i9 that engages the upper surface of the channel so that the control table may be held in its adjusted position and not move too freely from one position to the other. This control table is moved by a cable 21 that is attached to it by a cable clamp 20. The cable 2! passes over a pair of pulleys 22 and 24 that are suitably, mounted at spaced points in the instrument. Channel l6 and bar I! should be made as long as possible, and the supporting pulleys 22 and 24 should be just beyond the edge of these members so that the path of the cable along the channel will be straight. This does away with any tendency of the cable to lift the control table off the channel. The control table may be moved to any position along the It will be seen from the drawing that the rear part of the control table extends downwardly below the shaft ll. Journaled in the lower end of this portion is a shaft 28 that has attached to its front end a switch supporting member 29.

Mounted upon this member is a mercury switch 3| that is held in position by a switch supporting a clamp 32. The rearwardly extending portion of the shaft 28 has attached to it an arm as which is provided in its free end with a slot 33. Re-

ceived b the slot is a pin 34 that projects from the end of a U-shaped tilting member 38 that is pivoted to the table [3 at 36. This member has projecting downwardly from its front side a portion 3'! that is provided with a slot, the edges of which form projections 38 and 39.

' The member 3'! is tilted to move the mercury switch by a switch actuating member 4! which is fastened to a carriage 42 that is moved by the motor 8 as the latter is operated in response to potentiometer unbalance. Motion is imparted to this carriage to slide it along the shaft l1 upon which it is mounted by means of a cable 43 that is attached to the carriage by a cable clamp 44. The carriage is held in a proper position on shaft 1'! by a roller 45 extending from its upper face, the

roller being received by the channel member It. This carriage may also be provided with a pointer that cooperates with the scale 21 to indicate the position of the carriage and therefore the value of the temperatur being measured at any given time. Movement of the carriage may also be used to move, in any conventional manner, a pen across a chart. The cable 43 passes around pulleys 46, one of which is located at each end of the shaft H and around a drive pulley 41, rotation of which serves to pull the cable in one direction or the other and thereby move the carriage 42. Pulley 41 is fastened to a shaft 48 that has on it a drive gear 49, the latter being driven by a pinion 5| on the shaft of the drive motor 8.

The operation of the device should be apparent from the above description. A short summary, however, will be given. The attendant of the instrument rotates knob 25 to move control table I8 to a position corresponding to the value at which the temperature under measurement and control is to be maintained. There is enough friction provided in this system by spring is to prevent accidental movement of table !8 along the channel. 16 so that this table will remain in its adjusted position until it is again adjusted by an attendant. Thereafter, if the temperature being measured varies, carriage 42 will be moved relative to control table I8, and as it moves above or below this control table, the switch will be tilted in a direction to properly operate some temperature changing medium. As shown in the drawing, if the temperature varies in such a direction that the carriage 42 is moved to the right, operating member 4| will engage projection 39 on the part 35. The part 35 will then be moved in a counterclockwise direction to move the switch support in a clockwise direction and thereby open switch 3 l. Upon a return of the temperature to a value which will cause carriage 42 to move to the left, member 4| will engage projection 38 of the member 35 and thereb tilt the switch back to the position in which it is shown. The switch is connected by means of leads 52 to a terminal block 53. From this terminal block connections may be made with any suitable temperature controlling apparatus. The connections can be made in any conventional manner so that if the temperature is high, the temperature controlling medium will be reduced to thereby lower the temperature and vice versa.

, In Figures 3 and 4 there is shown a different embodiment of the invention. This embodiment differs in construction from that previously described in that the control table is more rigidly mounted than that of the previous embodiment and in that it is provided with latches to hold the mercury switch in the position in which it is moved. There is also provided a frictionless mounting for the carriage that is moved by the potentiometer motor 8 so that the carriage may roll along rod I! instead of being slid along that rod. Various parts corresponding to similar parts in Figure 2 have been designated by the same numeral used in that figure plus a letter.

In this case the supports 14a and [5a are extended downwardly below the rod Ila and have attached to their lower ends an inverted channel member 54. Received by the sides of this channel is a roller 55 that is attached by a bracket 56 to the downwardly extending portion of the control table l8a. Thus that table is held positively in a vertical position by the engagement of the upper portion thereof with channel 16a and by the engagement of the roller 55 with channel 5d.

The switch actuating member that is mounted on shaft 35a is in this case designated 51 and has projecting from its left side in Figure 3 an arm 58 by means of which the mercury switch is operated when the member 51 is tilted around shaft 36a. The front portion of member '51 is generally Y-shapedwith the two extending legs indicated by the reference numerals 59 and El. The lower ends of each of these legs is provided with a forwardly extending portion, as is best shown in Figure 4. Cooperating with the forwardly extending portions of legs at and iii are a pair of latch members $52 and 63 that are pivoted at 64 and 65 respectively on the control table l8a. Latch member 62 is provided with a portion 65 on its right end that is adapted to move to its dotted line position and engage the leg 59' of member 5? when the mercury switch is to be tilted in one direction. The latch cs is similarly provided with an end portion 6? that is adapted to engage the leg El to hold member 5? in position when it is tilted in a direction opposite from the direction shown in the dotted lines. Each of the latch members is provided with a downwardly extending portion (58. The portion 68 on latch 63 lies directly behind that portion of latch 62 and accordingly cannot be seen in the drawings. The latches are biased by springs as and ll, respectively, in a direction so that they tend to engage and hold the legs of the switch actuating member These springs could be omitted and the action of the latches be made dependent upon gravity if it is so desired.

The carriage which is moved by the potentiometer motor 8 in response to changes in the temperature measured is in this case designated by the reference numeral l2. This carriage is provided on each end with a pair of rollers 13 that engage the upper surface of the bar Na and roll along this bar as the carriage is moved. The carriage is also provided with a roller 74 that is received by the sides of channel lea. Rollers 13 and the roller "M definitely locate the carriage and keep it in an upright position as it is moved through its path in the instrument. A more positive location of the carriage may be obtained, if desired, by providing a roller it which engages the lower surface of shaft Ila. This roller is mounted. on a spring support It which in turn is fastened to the front of a downwardly projecting portion of this carriage. The force of spring is maintains roller 15 in engagement with shaft Ha andthereby also maintains each of the rollers lain engagement with the shaft.

Carriage i2 has attached to the upper portion thereof a blocl: '15 which serves to engage legsBl and 5d to-til-tmember. El. This block is formed near its, front end with a cam ll that cooperates with projections 68 on the latches to release these latches at such time as the carriage E2 is moving past control table Illa. It is noted that the cable 3 is attached to carriage H! by av pair of cable clamps 86, one of which is located on each side of the, projecting portion of spring it.

Mercury switch 3! and its supporting clamp 32 are, attached to a U-shaped switch supporting bracket is which in turn is pivoted on shaft 28 projecting forwardly from the lower portion of control table Eda. Bracket 18 is provided with an arm l5 extending to the left in Figure 3 by means ofjwhich the mercury switch may be tilted The outer end of arm 19 is connected by a link 8! with the outer end of arm 58 and through this link motion of member 51 is transmitted to the mercury switch support. In this case the terminals 52 of the mercury switch are passed around shaft 28 from which they extend to the terminal block '53' which is suitably located in the instrument;

In the operation of this embodiment of the invention, the control table [Ba is positioned at a point corresponding to the value at which the temperature is controlled. Movement of the carriage 12 to the right or to the left of the table l8a in Figure 3 is used to operate the mercury switch. Suppose, for example, carriage l2 had been to the left of the position shown in full lines; in Figure 3. If this were the case the parts on the table would be in their dotted line positions. Thereafter the change in temperature which caused carriage T2 to move to the right in Figure 3 produces the following operation. As the cam 11 moves beneath projections 53 of the latches, these latches will be lifted to the position shown in full lines in the drawing. This motion moves the end 66 of the latch 52 out of the path of leg 59 of member 51. Simultaneously the right edge of block 16 will engage the leg 5e and pivot the member 51' around shaft 36a. This movement continues until member 5! has been tilted counterclockwise in Figure 3 sufficiently for leg 6| to be behind the end 6'! of latch 63. Member 5? will then be locked in position by latch F33 to hold the mercury switch in its new position until such time as the carriage l2 again moves to the left. It is noted that neither of the latches is effective when the carriage I2 is exactly centered with respect to table l8a, as is shown in full lines in the drawing. At this point, however, the use of the latches is not necessary since block it is made of such a size that it will simultaneously engage both of legs 59 and iii of member 5? to hold that member in position without lost motion. When the temperature is at the control point, as it is with the position of the parts shown in full lines in the drawing, the control switch may be either opened or closed depending upon the arrangement that is used for the particular system under control. In each of the embodiments of' the invention already described, the guide members are located in a horizontal plane. It will be readily apparent, however, that they could be located in a vertical plane if desired. In such a case the switch support would be rotated through 90 from the position shown. An arrangement in which the switch operating members are moved vertically will nOW be described.

In Figures 5 and 6 there is shown another embodiment of' the invention. In these figures the same straight line movement of the part carrying the switchand of the part moved by the potenti'ometer motor'is retained. In this case, however, a different structure is used for the control table and the carriage, which moves in response to temperature variations. The switch 3i. is mounted on a support 83 which is rotatably attached to a control table takingthe form of a longitudinally movable rack member 84. This rack is guided at its upper end in a suitable bearing as shown and is-provided with a rod 85- extending from its lower end that is guided in a journal 8%; The rack or control table 84 is moved upwardly and downwardly in' order to adjust the control point of the instrument by means of a gear 8'! in mesh with the rack and a pinion 88 that drives the gear; This pinion may be provided with a knob similar to knob 25 if so desired, or the pinion maybe moved by a pointer 9| attached to the shaft thereof. This pointer cooperates with a scale 92 to indicate the control point for which the instrument is set. It is noted that there is provided: a. spring 89 attached at one end to the shaft of gear 81 and at its other end" to a fixed point 90 in order to takeup back-lash between the various parts; The leads from the" mercury switch 3| are wrapped around rod 85 in a helix before they are lead to the terminal block 53. In this manner the leads between the movable part of the mechanism and the terminal block are held in place and prevented from getting in the way of any of the movable parts of the instrument.

Support 83 is provided with two fingers 93 and 94 by means of which it is rotated around its pivot. Finger 93 cooperates with a flange 95 and finger 94 cooperates with a flange 9i; that projects upwardly from the surface of a carriage taking the form of a second rack member 97. The manner in Which these flanges are formed on the rack is best shown in Figure 6 in which it may be noted that one flange isin front of the other and that the upper end of flange 95 extends beyond the lower end of flange 96. I'his overlapping is equal to the distance between arms 93 and 94 where they engage the flanges. The rack tentiometer unbalance, the rack will be raised and lowered so that the flanges act on the fingers 93 and 94 of support 83 and tilt that support to work the control switch.

Some means is necessarily provided in instruments of this type to indicate the value of the temperature being measured. To this end there is provided a segment member 99 that is pivoted at ISIS. The lower surface of this segment is formed with gear teeth that mesh with the teeth of pinion on the shaft of the potentiometer motor 8 or are driven by this pinion through suitable gearing. Attached to the shaft the of the segment member is a pointer lei which cooperates with an indicating scale m2. It is noted that the two scales 92 and H12 are located side by will beheld in its adjusted position by engage- I ment between this finger and the top of flange 95. When the temperature has changed sufficiently for rack 9'1 to be lowered, the lower edge of flange 96 will engage finger 96 at the same time the upper edge of flange 95 moves below finger 93.

To have continued downward movement of rack 91 will produce a clockwise rotation of switch support 83, thereby moving this switch to its other position. Therefore, there will be no lost motion in the operation of this switch as the rack 91 moves past the control point. The switch support will always be positively held in one position or the other or will be positively held as it is being moved between its two positions.

From the above description it will be seen that I have provided a novel type of control mechanism in which the operating parts of an instrument are moved in a straight line and parallel to each other. As the parts pass each other, the control switch will be thrown from one position to another. occur may be readily adjusted so that the point at which the control switch is operated is definitely located with respect to the scale of the instrument. Also because of the relatively long path The point at which this passing will of travel of the control table and the carriage, the instrument is very sensitive. This is true since the movement of the carriage required to throw the control switch from one position to the other is only a small percentage of the range of the instrument.

While in accordance with the provisions of the statutes, I have illustrated and described the best forms of the invention now known to us, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention as set forth in the appended claims, and that in some cases certain features of the invention may sometimes be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a potentiometer having a measuring instrument sensitive to a variable under control and a motor responsive to the variations of said variable sensed by said measuring instrument, a control table mounted in said potentiometer for straight line movement, a cable secured to said control table, a manually operable knob having driving engagement with said cable for adjusting said control table, a control switch pivotally mounted on said control table, a switch actuating member pivotally mounted on said control table, and having driving engagement with said switch to move it from one position to another, and a carriage driven by the motor of the potentiometer in straight line movement into and out of engagement with said switch actuating member.

2. In a potentiometer having a motor responsive to the variations of a variable under control, means for actuating electric control switches including, a carriage mounted in said potentiometer for straight line movement, a cable driven by the motor of the potentiometer and connected to said carriage so as to drive it, a control table mounted in said potentiometer adjacent the straight path of motion of said carriage, a control switch pivotally mounted on said control table for movement into circuit-making and circuit-breaking position, and a switch actuating member pivotally mounted on said control table and having a portion extending into the path of motion of said carriage so as to be engaged thereby and having driving engagement with said switch 'to move it to one of its various positions when said actuating member is engaged by said carriage.

3. In a potentiometer having a measuring element sensitive to a variable under control and a motor movable in response to the variations of said variable as sensed by said measuring element, a pair of fixed supports, a pair of straight U-shaped channels secured to said supports, a straight rod secured to said supports, intermediate said channels, a control table slidably 'mounted onone of said channels, a flexible cable secured to said control table, a manually operable knob having driving engagement with said flexible cable for moving said control table for thereby setting the control point of the potentiometer, a switch pivotally mounted on said control table for movement between its circuit-making and its circuit-breaking positions, a switch actuating member pivotally mounted on said control table and having driving engagement with said switch for moving it between its circuitmaking and its circuit-breaking positions, a.

carriage having a pair of rollers pivotally mounted thereon and supporting said carriage for movement along said rod and having a third roller pivotally mounted thereon riding on the inside of one of said channels, a cable engaging with said carriage and driven by the motor of the potentiometer to move the carriage along the rod so that said carriage engages said switch actuating member and thereby actuates said switch between its circuit-making and circuitbreaking positions.

4. In a potentiometer having a motor movable in response to the variations of a variable under control, a guide supported in said potentiometer, a control table slidable along said guide, a cable secured to said control table, a manually operable knob having driving engagement with said cable for adjusting said control table, a spring engaging said control table and said guide and providing a yielding connection therebetween, a switch pivotally mounted on said control table,

a switch actuating member pivotally mounted on said control table and having driving engagement with said switch and having an extending portion, and a carriage mounted in said potentiometer for movement along a fixed path so as to engage the extending portion of said actuating member and thereby turn said switch about its pivot between its circuit-making and its circuitbreaking positions.

GREGOR W. KUNTNY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,748,983 Hofstetter Mar. 4, 1930 1,820,990 Siebs Sept. 1, 1931 20 1,946,280 Harrison Feb. 6, 1934 2,431,929 Goff Dec. 2, 1947

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