US2165555A - Control device - Google Patents

Description

y 1939- c. G. KRONMILLER ET AL 2,155,555

CONTROL DEVICE Filed Aug. 6, 1936 OarZ G. Kfiorzmflkr 3% Frederick D Joesiz'izg Patented July ll, 1939 2,1655% CONTROL DEVICE Carl G. Kronmiller and Frederick D. Joestlng,

Minneapolis, Minn., assignors to Minneapolis- Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application August 6, 1936, Serial No. 94,530

14 Claims. (01. 200-112) Our invention relates to a control device, and tion of any control device which is moved from more particularly to a switch controlled by a conone controlling position to a second controlling dition responsive meansposition by changing the angular position thereof.

It is common to employ for various control pur- Other objects of our invention will be apparent poses a switch which will remain in closed posifrom the accompanying specification, claims and tion only when some controlling condition has a drawing, of which desired value. A particularly common use for Figure 1 is a view of our controlling device as such a switch is in a safety pilot in a fluid fuel applied to a mercury switch with the switch in burner control system wherein the switch will one circuit controlling position, l0 remain closed only when the pilot is burning. In Figure 2 is a view of the same device with a certain of such switches, a manual operating switch shown in a different circuit controlling means is provided which is effective to close the position, and switch only when the controlling condition has Figure 3 is a schematic view of our device apthe desired value. With this type of structure, it plied to a gas burner control system.

13 has further been proposed to provide means Referring to Figure]. of the drawing, a switch whereby the manual operating means is inefiecis shown as located within a housing Ill. Setive to open the switch while the controlling concured to the rear wall of this housing is a U- dition has the desired value. shaped bracket ll having forwardly extending In these prior structures, the switch employed legs I2 and- I3. Slidably mounted in the forhas been an open contact switch which is actuwardly extending legs l2 and i3 of bracket ll 20 ated between open and closed position by a more is a bar member it. Secured to thebar I6 is a or less rectilinear movement of one or more collar 15, and interposed between said collar switch elements. The present invention is parand the lower forwardly extending leg i3 is a ticularly concerned with such a device wherein a spring l6 which serves to yleldably urge bar I l mercury switch, or some other switch which is upwardly. Attached to bar ldthrough a pivot 25 actuated between open and closed positions by i8 is a lever l9. The pivotal movement of lever tilting thereof, is employed. ()ur invention furl9 about pivot I8 is limited by a pin 20 also ther provides an additional safety factor in that secured to member It and extending into an after the switch has been moved to closed posiarcuate slot H in lever is.

tion, the actuating means is not only ineffective Lever I9 is provided with an upwardly extendto open said switch but is inefiective to apply any ing extension 22 which in the position shown in force to any of the members directly associated Figure 1 lies in the path of movement of an with the switch. actuator member 23. Actuator member 23 is slid- An object of the present invention is accordably mounted in the leg l2 of member H and in ingly to provide a switch or other control device the upper wall of housing ill. Secured to the 35 having an actuating means which upon the member 23 is a collar 26 and interposed between switch or other control device being moved to a said collar and leg I2 is a spring 25 which serves desired controlling position is ineffective to alter to bias member 23 upwardly. It will be readily the position of the device or to even apply a force seen that upon member 23 being pushed downtending to alter the position thereof. wardly, the lower end thereof engages the ex-I A further object of the presentinvention is to tension 22' of lever l9 moving the entire lever provide a switch of the type set forth in the along with strip l4 downwardly. Since the actuprevious object wherein the switch is held in the ator member 23 is in line with pivot l8 and pin desired controlling condition only during the 20 or slightly to the right thereof, such downduration of a certain condition and upon the Ward movement of actuator 23 will not cause 5 termination of said condition, the switch is moved member l9 to be tilted. toadifierent controlling position regardless of the Pivotally secured to member is is a rod 21. position of the actuating means. This rod has secured thereon at its lower end Our invention further resides in the particular through a clip 28 an armature member 2a of structural features by which we obtain a device suitable magnetic material. This armature 29 is of the type discussed which is adapted for use designed to cooperate with the core 30 of an with a tiltable switch. While we have shown our electromagnet 3i. Rod 27 extends through the device as employed in connection with a mercury upper wall 32 of a housing 33 for electromagnet switch, it is to be understood that the structure 3!. A spring 35 is interposed between the upper g5 employed is of broad general utility for the operaend of rod 2i and the upper wall 32 of housing 33. This spring serves to bias rod 21 upwardly causing lever I9 to assume the angular position shown.

A thermo-couple is generally indicated by the numeral 31. This thermo-couple comprises the usual elements 38 and 39 of different thermoelectric characteristics which are joined at 49 to provide the hot junction" of a thermo-couple. While the metals employed for elements 39 and 39 may be any metals having suitable dissimilar thermo-electric characteristical have found it desirable to employ an inner member of Constantan, an alloy comprising approximately fifty per cent nickel and fifty per cent copper, and an outer member 39 of stainless steel. The stainless steel employed may be any suitable stainless steel capable of adequately resisting the heat of the pilot burner flame where the device is intended to be employed in connection with a pilot burner.

The inner member 38 is connected to a conductor 4| which is suitably insulated as at 42. The outer member 39 is connected to a copper reducing sleeve 43, which in turn is connected to a copper tube 44. The conductor 4| is electrically joined through a metal coupling sleeve with one terminal of the winding of electromagnet 3|. Surrounding the metal sleeve 45 is an insulating bushing 46 and surrounding this bushing is a copper sleeve 41 which is rolled. down to engage the copper tube 44. Electrically connected to sleeve 41 is the other terminal of the winding of electromagnet 3|. In order for the rather small electromotive force generated by the thermocouple to produce a sufficient holding action of electromagnet 3|, the conductor 4|, copper tube 44 and the winding of the electromagnet are all of relatively large size to provide an extremely low resistivity. By reason of this fact, sufilcient force is generated in the electromagnet 3| so that when the armature 29 is moved into engagement with the pole pieces of core 30, the electromagnet is able to hold the same in said position against the action of spring 35.

As pointed out previously, our device is particu- A larly applicable for use with a switch which is moved from one circuit controlling position to a second controlling position by tilting thereof, such as a tiltable mercury switch. We have accordingly shown a mercury switch 49 mounted on the lever I9. This mercury switch is secured to lever I9 in any suitable manner, such as by a. clip 59. A switch 49 comprises in the usual manner a container 5| in which is housed a plurality of electrodes 52 and a mercury globule 53. In the usual manner, when the switch is tilted, the mercury is caused to shift its position so as to bridge the electrodes 52: Connected to electrodes 52 are conductors 55 which are connected to suitable terminals 56 of a terminal block 51. Although we have shown one pair of electrodes in switch 49, it is understood any desired number of electrodes may be employed and if desired one pair may be employed at each end of the container so that one pair of electrodes are bridged when the switch is in one position and a second pair bridged when the switch is in the other position.

As previously pointed out, when actuator member 23 is moved downwardly with the members in the position shown in Figure 1, the end of the actuator engages the extension 22 of lever l9 and moves the entire lever l9 downwardly along with masses has no effect upon the circuit controlling position of switch 49. This downward movement of lever I9 causes armature 29 to be moved into engagement with the poles of core 39 of electromagnet 3 I. Unless the thermocouple is energized so as to energize electromagnet 3|, springs 35 and I9 will be eflectlve to return lever I9 to its original position without tilting thereof. If, however, the electromagnet is energized, armature 29 will be held downwardly against the action of spring 35. At the same time, spring I 9 will be eiIective to move bar member I4 upwardly, carrying upwardly the right-hand end of lever I9 so that the parts now assume the position shown in Figure 2.

It will be noted that in the new position of elements, switch 49 is changed in angular position from that occupied in Figure 1 so that the mercury 53 is now bridging electrodes 52 causing a circuit to be established therebetween. It will further be noted that the tilting of lever I9 has caused the upwardly extending extension 22 to be moved out of the path of movement of member 23 so that further movement of actuator 23 has no effect whatsoever upon either member I4 or lever I9. In this manner, we insure that movement of actuator 23 after the switch has been closed is not only inefiective to open such switch but is ineffective to apply any force to any of the members directly associated therewith, tending to open said switch.

If actuator 23 is moved downwardly and held in that position in an attempt to prevent opening of the mercury switch, the switch will, nevertheless, open upon the deenergization of the thermocouple. This is due to the fact that while actuator 23, in its lowermost position prevents a complete return movement of lever l9, due to the fact that it lies in the path of arm 22 of the lever, sufilcient return movement of lever I9 is permitted to open the switch. Thus it is impossible for an operator to prevent operation of the switch by securing actuator 23 in its innermost position.

As previously stated, the particular structure employed is of broad general utility for use with various control devices. It is particularly applicable for use as a safety pilot in a fuel burner control system. In Figure 3, we have shown it so used. Referring to said figure, a conventional gas burner is indicated by the reference numeral II. This gas burner 1| is connected through a pipe I2 with a valve 13 which controls the flow of gas to said burner from a gas main I4. Valve I3 may be of any suitable power actuated type and is shown as comprising a valve body 15 and a suitable power operated valve actuating means I9.

A pilot burner 11 is connected through a pipe 19 with the gas supply pipe I4. Located adjacent to said pilot burner 11 is the thermo-couple 31 of our improved control device.

A step-down transformer 19 supplies power for the operation of the system. This transformer comprises a line voltage primary 99 and a low voltage secondary 9|. The primary 99 is connected to line wires 92 leading to any suitable source of power (not shown).

A thermostat 99 of conventional form is shown as controlling the operation of the gas valve 13. This thermostat comprises a bimetallic element 95 to which is attached a contact arm 99. The contact arm 99 is moved by the bimetallic element 99 into engagement with a contact 91 upon the temperature dropping below a predetermined value.

After the pilot TI is ignited so that thermocouple 31 is heated, the moving of actuating menber 23 inwardly and releasing the same causes the switch within housing ID to be closed, in the manner previously described. When the temperature drops below the value desired to be maintained, the contact arm 86 will be caused to move into engagement with contact 81, In other words, the thermostat calls for heat. Upon this taking place, the following circuit is established: from the right-hand .terminal of secondary 8| through conductor 90, bimetallic element 85, contact arm 86, contact 81, conductor 9|, switch l0, conductor 92, motor 16 and conductor 93 to the left-hand terminal of secondary 8|. This causes the valve 13'to be opened with the result that gas is supplied to the burner H, the gas being ignited by the pilot 11. In a normal operation, this continues until the temperature in a room or a space to be heated has risen above the desired value so that contact arm 86 separates from contact 81, or in other words, until the thermostat is satisfied". Upon this taking place, a circuit through valve motor 16 is broken and the valve is closed. If at any time .the pilot burner 11 is extinguished, the thermocouple 3! will very rapidly cool off, allowing the switch of the safety pilot to open, thus interrupting the portion of the circuit between contact 81 and the motor 16. With the switch open, it is impossible for the valve to be opened or to remain open.

It will be seen that we have provided a control device of particular applicability as a safety pilot wherein it is impossible to close a switch or other controlling device so long as the controlling condition, such as a temperature adjacent a pilot burner, has a desired value, and wherein, after the switch is closed, it is impossible to even apply an opening force to the same by operation of the actuating means. Furthermore, it is impossible to prevent opening of the switch upon extinguishment of the pilot burner. It will further be seen that our construction is relatively simple and is of general utility wherever it is desired to change the angular position of a member and to prevent such change being effective unless a predetermined condition exists.

While we have shown a specific embodiment of our device, it is to be understood that this is for purposes of illustration only and that our invention is to be limited only by the scope of the appended claims.

We claim as our invention:

1. In combination, a switch, a switch actuating member movable between first and second positions, and operative upon movement to ,said second position to move said switch between first and second positions without changing the circuit controlling position of said switch, selectively operable holding means, and means operative upon said holding means being efiective and upon said actuating member being returned to said first position to move said switch from saidsecond to a third and different circuit controlling position, said third position being such that said actuating member is free to move between said first and second positions but is inoperative to cause movement of said switch.

2. In combination, a controlling member comprising elements movable from one controlling position to a second controlling position upon change in angular position of said member, supporting means for said member comprising a pivot, actuating means for moving said pivot from a first to a second position to move said controlling member without changing the angular position thereof, and means for pivotally holding said member at a point spaced from said pivot when said member is in the position assumed during the second position of said pivot so that upon movement of said pivot back to said first position, said member is changed in angular position to cause the elements thereof to move to said second controlling position.

3. In combination, a controlling member comprising elements movable from one controlling position to a second controlling position upon change in angular position of said member, supporting means for said member comprising a pivot, actuating means for moving said pivot from a first to a second position to move said member without changing the angular position thereof, and means, including an electromagnet, for pivotally holding said member at a point spaced from said pivot when said member is in the position assumed during the second position of said pivot so that upon movement of said pivot back to said first position, said member is changed in angular position to cause the elements thereof to move to said second controlling position.

4. In combination, a switch having spaced electrodes and a movable conductive liquid element adapted to be moved into and out of bridging engagement with said electrodes upon change in angular position thereof, actuating means for moving said switch between predetermined positions without changing the angular position thereof sufliciently to cause the liquid element to bridge the electrodes, and further selectively operable means effective when operable to vary said movement of said switch by said actuating means to cause a sufficient change in the angular position of said switch to cause such bridging of the electrodes.

5. In combination, a switch movable between different circuit controlling positions upon change in angular position thereof, a pivotally mounted support for said switch, actuating means for moving said support and said switch between predetermined positions without changing the angular position thereof and means selectively operable to pivotally hold said support at a point spaced from the pivot point of said support to vary the movement thereof by said actuating means to cause a change in the angular position of said switch.

6. In combination, a switch movable between different circuit controlling positions upon change in angular position thereof, a pivotally mounted support for said switch, actuating means for moving said support and said switch between pre- 5 determined positions without changing the angular position thereof and means, including an electromagnet, selectively operable to pivotally hold said support at a point spaced from the pivot point of said support to vary the movement thereof by said actuating means to cause a change in the angular position of said switch.

7. In combination, a switch movable between different circuit controlling positions upon changein angular position thereof, a pivotally mounted support for said switch, actuating means for moving said support and said switch between predetermined positions without changing the angular position thereof, and means selectively operable to pivotally hold said support at a point spaced from the pivot point of said support to vary the movement thereof by said actuating means to cause a change in the angular position of said switch, said actuating means being ineffective to cause movement of said support after said change in angular position thereof.

8. In combination, a switch movable between different circuit controlling positions upon change in angular position thereof, actuating means for moving said switch between predetermined positions without changing the angular position thereof, and further selectively operable means effective when operable to vary said movement of said switch by said actuating means to cause a change in the angular position-of said switch, said actuating means being ineffective to cause movement of said switch after said change in angular position. i

9. In combination, a support, a member slidably mounted on said support, a lever pivotally secured to said member, a switch mounted on said lever. said switch being movable between different circuit controlling positions upon change in angular position thereof, a switch actuator slidably mounted on said support, said lever having a portion lying in the path of movement of said actuator when said lever is in one angular position, said actuator being effective upon movement thereof to engage said portion to slide said lever and the switch mounted thereon without changing the angular position thereof, and selective operable holding means effective when operable to pivotally hold said lever at a point spaced from the point at which it is secured to said slidable member to cause said lever to be tilted upon motion thereof being caused by said actuator.

10. Incombination, a support a member slidably mounted on said support. a lever pivotally secured to said member, a switch mounted on said lever, said switch being movable between different circuit controlling positions upon change in angular position thereof, a switch actuator slidably mounted on said support, said lever having a portion lying in the path of movement of said actuator when said lever is in one angular position, means for biasing said slidable member and the lever secured thereto in the direction of said actuator, said actuator being effective upon movementthereof to engage said portion to slide said lever and the switch mounted thereon against the action of biasing means without changing the angular position thereof, and selectively operable holding means effective when operable to pivotally hold said lever at a point spaced from the point at which it is secured to said slidable member to cause said lever to be tilted upon motion thereof being caused by said biasing means.

11. In combination, a support, a member slidably mounted on said support, a lever pivotally secured to said member, a switch mounted on said lever, said switch being movable between different circuit controlling positions upon change in angular position thereof, a switch actuator slidably mounted on said support, said lever having a portion lying in the path of movement of said actuator when said lever is in one angular position, said actuator being effective upon movement thereof to engage said portion to move said lever and the switch mounted thereon without changing the angular position thereof, and selectively operable holding means effective when operable to pivotally hold said lever at a point spaced from the point at which it is secured to said slidable member to cause said lever to be tilted upon motion thereof being caused by said actuator, said tilting of said lever being effective to move said portion lying in the path of movement of said actuator out of said path of movement so that further movement of said actuator is ineffective.

to cause movement of said lever.

12. In combination, a switch movable between different circuit controlling positions upon change in angular position thereof, selectively operable holding means for an element associated with said switch, reciprocable means effective when moved in one. direction to move said element into cooperative relationship with said holding means without changing the angular position of said switch, and means operative upon movement of said reciprqcable means in the direction of its original position and upon said holding means being effective to change the angular position of said switch.

13. In combination, a switch movable between different circuit controlling positions upon change '81 angular position thereof. selectively operable holding means for an element associated with said switch, reciprocable means effective when moved in one direction to move said element into cooperative relationship with said holding means without changing the angular position of said switch, and means operative upon movement of said reciprocable means in the direction of its original position and upon said holding means being effective to change the angular position of said switch, said reciprocable means being ineffective in the new position of said switch to aifeet the position thereof.

14. In combination, a switch having spaced electrodes and a movable conductive liquid element adapted to be moved into and out of bridg ing engagement with said electrodes upon change -in angular position thereof, selectively operable holding means for an element associated with said switch, reciprocable means effective when moved in one direction to move said element into cooperative relationship with said holding means III without changing the angular position of said I switch, and means operative upon movement of said reciprocabl'e means in the direction of its original position and upon said holding means being effective to change the angular position of said switch,

CARL G. KRONMILLER. FREDERICK D. JOESTING.

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