US2340197A

US2340197A - Safety switch

Info

Publication number: US2340197A
Application number: US394601A
Authority: US
Inventors: Harold A Mantz
Original assignee: Milwaukee Gas Specialty Co
Current assignee: Milwaukee Gas Specialty Co
Priority date: 1941-05-22
Filing date: 1941-05-22
Publication date: 1944-01-25
Anticipated expiration: 1961-01-25

Description

SAFETY swi'rcn Jaw 25, 1944. H. A. MANTZ Filed May 22, 1941 2 Sheets -Sheet 1 Jan. 25;"1944.

H. A. MANTZ SAFETY SWITCH Filed May 22, 1941 2 Sheet-Sheet 2 v fiaroZcZJlManiz eta/ UNITED STATES PATENT OFFICE SAFETY SWITCH Application May 22, 1941, Serial N0. 394,601

7 Claims.

This invention relates, generally, to protective devices for burner apparatus, and it has particular relation to a safety switch adapted to be controlled by condition responsive means, and operative to prevent the escape of unburned fuel.

While the particular device which I shall describe hereinafter in connection with the drawings is a safety switch, operative to cause a valve in the fuel supply pipe leading to a burner to close whenever a, flame to which the device is responsive-as a pilot flame-goes out, it is to .be understood that the invention, in its broader aspects, is not limited to this particular use but may be employed in all similar work as suitable or desired.

Moreover, while I have shown and shall describe the switch of the present invention in connection with a valve that requires current only for opening the same, the invention is not limited to use with valves of this particular type, but may be employed with valves that require current for both opening and closing the valve, and it is to be understood that the switch may be used for controlling other circuits and other devices than the particular circuit and particular device selected for illustration.

One of the main objects of the invention is to provide an improved form of switch embodying a simple and improved mode of operation for opening the circuit into which the switch is connected, for example, upon extinguishment of the flame to which the device is responsive, or upon the occurrence of some other abnormal condition or malfunctioning of the apparatus; also a simple and improved mode of operation which will permit resetting the switch to closed position only when the flame to which the device is responsive is burning, or when the other abnormal condition or malfunctioning of the apparatus is cured.

Another object of the invention is to provide a switch of the character described which is of simple, inexpensive, and improved construction embodying few parts, and operative effectively to accomplish the purposes set forth.

Another object of the invention is to provide. in a switch of the character described, simple and improved means for indicating the position of the switch.

While the particular structural features and combinations by which I obtain a device of the character set forth are important features within the more specific aspects of the invention, it is to be understood that the precise features shown and described may be varied within the broader aspects of the invention.

In order to acquaint those skilled in the art with theconstruction and operation of a safety switch embodying the present invention, I will now describe, in connection with the drawings, one preferred embodiment of the invention.

In the drawings:

Figure 1 is a front view of a safety switch embodying the present invention, partially in section and with the cover removed, and showing the switch in closed position;

Figure 2 is a detail section taken on the line 2-2 of Figure 1;

Figure 3 is a detail section taken on the line 3-3 of Figure 2;

Figure 4 is a more or less diagrammatic view showing the switch in side elevation and in connection with burner apparatus;

Figure 5 is a fragmentary detail view showing the position of the switch actuator and reset means, with the reset member pressed inwardly to cock or reset the device; and

Figure 6 is a view similar to Figure 5 showing the position of the switch actuator and reset means, with the switch in open position and the reset member and reset stem released.

In Figure 4 of the drawings, a gas or other fuel burner of any suitable or preferred type is conventionally illustrated at III. The burner Ill may be the burner of a room or space heater, water heater, floor furnace, gas range, or any other burner. A gas or other fuel supply pipe II leads to the burner III for the delivery of gas or other fuel thereto-for example, through a mixing chamber (not shown) to which air is admitted in the usual way, as well understood In the art.

A power actuated or electroresponsive valve I2, such as a solenoid or motor valve, is interposed in the fuel supply pipe I I. The valve I2 is shown as comprising a valve body I3 and a hood I4 having suitable power operated valve actuating means therein. A step-down transformer I5 supplies power for the operation of the valve I2. This transformer comprises a line voltage primary I6 and a low voltage secondary II. The primary I6 is connected to line wires I8 leading to any suitable source of current or power (not shown). The valve actuating means for the valve I2 is connected into the secondary circuit I 9. The control switch of the present invention is also connected into the secondary circuit I9, as will presently appear.

For purposes of illustration, it may be assumed.

that the valve i2 is of a character to be actuated to open position by closing of the circuit I9, and to be held in open position to supply fuel or operative energy to the burner I as long as the circuit I9 is closed. The valve l2 may have spring means, or other suitable means, for actuating the valve to closed position to shut off the supply of fuel to the burner l0 when the circuit I9 is opened or otherwise disabled.

The control switch of the present invention is shown as located within a housing 20. The opposite ends of the back wall of the housing are turned in to form end walls 2 I, and at the opposite sides of the back wall are inturned flanges 22. The cover 23, which may be of generally U-shaped cross section, fits over the inturned end walls 2| with the inner marginal edges of the sides of the cover fitting over the flanges 22. Slots 24, opening inwardly from the inner marginal edges of the side walls of the cover, fit over the shanks of screws 25 having threaded engagement in the side flanges 22. These screws 25 are adapted to be tightened to secure the cover in place on the base of the housing and to be loosened to permit removal of the cover. The screws 25 and slots 24 may be positioned at different distances from the opposite ends of the device to assure proper mounting of the cover 23.

The front wall of the cover 23 has an opening 28, shown in dotted lines in Figure 4, through which an indicator is adapted to be viewed to indicate the position of the switch, as will hereinafter appear.

An actuator or reset member 30 operates between open and closed positions by rectilinear movement through an opening 3| in the adjacent end wall 2| of the housing. The outer end of the actuator member 30 is provided with an operating button 32. The actuator member 30 is shown as comprising a pair of actuator member parts forming a fork at the inner end of the actuator member and secured together outwardly of the forked inner end. A pin 34 secured in the actuator member 30 outwardly of its forked inner end cooperates with the adjacent end wall 2| to limit outward movement of the actuator member.

The actuator member 30 is yieldingly retained in its outwardly projected position as shown in Figures 1 and 6. and upon release of the button 32, as will presently appear, is returned to this outwardly projected position by a coiled return spring 36. This spring 36 is shown as connected between the inner end of the actuator member 30, at 31, and a spring anchoring lug 38 pressed inwardly from the adjacent end wall 2| of the housing.

A reset member 40 extends between the sides of the forked inner end of the actuator member 30. The inner end of the member 40 has a bifurcation or slot at 4| within which a cam lever 42 is pivoted on a pin 43, the opposite ends of which pin extend into longitudinal slots 44 in the opposite sides of the forked inner end of the actuator member 30. The cam lever 42 has a cam slot 45 through which extends a pin 46, the opposite ends of which are secured in the opposite sides ofvthe forked inner end of the actuator member 38.

The cam lever 42 has secured thereto, for example, at 48, an over-travel spring arm 49 for actuating the switch to closed position. The lever 42 also carries a flag or indicator member 50. This indicator member has "on and ofi" markings thereon as shown, or is provided with colored or other appropriately marked portions for indicating through the opening 26 in the switch cover 23 the position of the switch, as will presently appear.

The means for holding the reset member 40 in the position shown in Figure 1, so that the switch will close when the actuator member 30 is released following its inward resetting movement and will remain closed as long the the member 40 is held in the position shown and the actuator member 38 is in its outwardly projected position, is shown in the form of an electromagnet located within the housing 20. The electromagnet selected for illustration comprises a magnet frame 56 secured to a terminal bushing 51 by a terminal tip H36, headed at its lower end and peened over at its upper end, with the parts suitably insulated from each other, as shown. The coil 58 of the electromagnet is wound around the legs of the magnet frame 56 and has one end grounded to the bushing 51 in any suitable manner. The bushing 51 is shown as extending through an opening 59 in the adjacent end wall 2| and as externally threaded for threaded engagement at 60 with a nut 62 by means of which the bushing is clamped in place in the end wall 2| of the switch housing.

The electromagnet has an armature 84 attached at 65 to the adjacent end of a stem 66, if desired, in a manner to permit self-accommodation of the armature when in attracted position to the pole ends of the magnet frame 56. The electromagnet and armature are enclosed within a cup 68. The stem 66 extends for reciprocatory movement through an opening 89 in the inner end of the cup 58. The opening 89 is sealed by suitable sealing material, such as a leather washer, felt packing or the like, as indicated at in, interposed between the inner end of the cup 68 and a spring seating disc 12. The end of the stem 66 opposite the end on which the armature 64 is mounted is secured, for example, by a pin 13 to the adjacent end of the reset member 40. A coiled spring 14 interposed between the spring seating disc 12 and a spring seat member 15 actuates the armature 64 to retracted position and the reset stem 86 and reset member 40 to the position shown in Figure 6 when the electromagnet is deenergized, for example, upon extinguishment of the flame to which the device is responsive.

The particular switch selected for illustration is indicated in its entirety at 18, and is shown as comprising a pair of contacts or contact pins positioned in spaced relation and suitably insulated from each other and the other parts of the device. The contact pins 80 are connected to terminals 82. The conductors IQ of the circuit for the valve I2, which conductors are insulated at 84, enter the housing 20 through an insulating grommet 85. One of the conductors 9 is connected to the terminal 82 for one switch pin 80, and the other conductor I9 is connected to the other terminal 82 for the other switch pin 80.

The switch stem 88 has rectilinear sliding movement in the insulating base or block of the switch 18, with the outer end of the stem in position for cooperation with the free end of the switch operating spring arm 49 on the cam lever 42. Within the switch block the reduced inner end of the stem 88 passes through a bridging contact plate 90. A coiled spring 92, surrounding the reduced inner end of the stem 88 and interposed between the contact plate 90 and an abutment 93 on, or forming a part of, the switch base, yieldingly urges the plate 30 out of bridging contact with the contacts 80 to open the circuit I9. By engagement of the contact plate 90 with the shoulder 94 on the stem 88, the spring 92 also yieldingly urges the stem 88 to its outwardly projected position as shown in Figure 6. Stop means (not shown) may be provided for limiting the outward movement of the switch pin 88 under the action of the spring 92.

The pilot burner 95, which is located in juxtaposition to the main burner I to maintain a pilot light for lighting the main burner, is supplied with gaseous fuel by a pilot supply pipe 96. The pilot supply pipe 96 may be connected with the main fuel supply pipe I I anterior of the valve I2, or it may be supplied with fuel for delivery to the pilot burner in any other desired manner.

A thermocouple, indicated at 98, is placed in position so that the hot junction 99 thereof will be heated by the pilot flame as long as the pilot flame is burning. The construction of the thermocouple may be similar to that more fully disclosed in Oscar J. Leins Patent No. 2,126,564, granted August 9, 1938, or a thermopile, or any other form of thermoelectric generator may be employed.

For the purpose of the present description, suffice it to state that the particular thermocouple 98 selected for illustration comprises an outer tubular thermocouple member and an inner metallic thermocouple member of different thermoelectric characteristics. The inner thermocouple member is joined at one end to the outer end of the outer thermocouple member to form the thermojunction 99 which is placed in position to be heated by the pilot fiame. An inner lead conductor I00 is joined to the inner thermocouple element to form an internal thermojunction I02, and an outer tubular lead conductor I03 is connected to the outer thermocouple member, for instance through a sleeve, to form a third thermojunction. The lead conductors are of flexible character so as to be readily bent to insure neat installations. The inner lead conductor I00 is insulated from the outer lead conductor I 03, for

instance, by a wrapping of insulation I04 on the inner lead conductor.

A quick detachable or removable connection is preferably provided between the coil 58 of the electromagnet and the ends of the leads I00 and I03 opposite the ends which are connected to the thermocouple. Thi removable lead connection may be of any suitable or preferred form. Sufiice it to state that the inner lead I00 has a connector cone I05 which seats in the correspondingly recessed outer end of the terminal tip I06 and is clamped in contact therewith by a connector sleeve I01. The adjacent end of the outer tubular lead conductor I03 is connected in circuit with one side of the coil 56 through the bushing 51, and the other side of the coil is connected to the terminal tip I06, the parts being suitably insulated as shown.

To start the operation of the system shown in the drawings. the following sequence is followed:

The actuator or reset member is pressed inwardly from the position shown in Figure 6 by engaging the button 32 with the hand or fingers and imparting pressure thereto. The armature 64 is in released or retracted position. and the spring 14 holds the pin 43 in engagement with the inner ends of the slots 44. As a result, the inward movement of the actuator member 30 moves the reset stem 66 with it in the same direction until the armature 64 is cooked or set in- III Qb'rlIIIH NOW to attracted position against the pole ends of the magnet frame 56.

The pilot burner 95 is lighted, or, having been lighted, heats the thermoelectric generator, and the actuator member 30 is held pressed-inwardly until the heat of the pilot flame on the thermoelectric generator has energized the electromagnet sufficiently so that it will hold the armature 64 attracted thereto.

When the electromagnet is energized sufficiently to hold the armature 64 in attracted position, the actuator member 30 is released and the reset stem 66 and reset member 40 remain in cocked position holding the pivot 43 for the cam lever 42 in the position shown in Figure 5. The switch operating spring arm 49 assumes the position shown in Figure 5 when the actuator member 30 is pressed inwardly. Then with the armature held attracted to the magnet frame 56, thereby holding the pivot 43 for the cam lever 42 in the position shown in Figure 5 when the actuator member 30 is released, the outward movement of the actuator member 30, under the action of the spring 36, causes the pin 46, by its outward movement in the cam slot 45, to swing the arm 49 in a counterclockwise direction (Figures 1 and 5') about the pivot 43 from the position shown in Figure 5 to the position shown in Figure 1. The arm 49, by cooperation with the outer end of the switch pin 88 in this movement, moves the contact plate 90 inwardl against the action of the spring 92 and into bridging contact with the contacts to close the circuit I9. The circuit is thus closed not by the inward movement of the actuator member 30, but by the movement of this member 30 to its outwardly projected position following the resetting operation and only when the electromagnet is effective to hold the armature 64 in attracted position. The over.- travel character of the spring arm 49 assures good firm contact of the contact plate with the contacts, there being preferably some overtravel of the cam lever 42 after engagement of the contact plate 90 with the contacts 80 which tensions the spring arm 49 to assure firm and tensioned contact.

If the pilot burner is not lighted to produce the thermoelectric current for holding the armature 64 in attracted position upon setting the same to that position by the actuator member 30, the armature 64 and reset stem 66 will move to retracted position upon release of the actuator member 30, the spring 92 at this time maintaining the switch plate 90 in open position.

If. after the parts are set as shown in Figure 1 and the pilot burner is lighted to hold the parts in the position shown in this figure, the pilot burner is extinguished, the armature 64 is released and the spring I4 then operates to move the armature 64 to retracted position. The cam lever 42 moves outwardly with the movement of the reset stem 66 to released position through the pin connection at 43, and the cam slot 45 cooperating with the pin 46 by this movement of the cam lever 42 relative to the actuator member 30 swings the arm 49 in a clockwise direction about the pivot 43 to the position shown in Figure 6. This releases the switch pin 88 and the spring 92 separates the contact plate 90 from the contacts 80. This opens 01' interrupts the circuit I9, and the valve I2 operates to closed position to shut off the supply of fuel to the main burner.

When the armature is in retracted position with the actuator member 30 in released position as shown in Figure 6, the of! marking on the indicator arm is positioned to be viewed through the opening 26 in the cover of the housing to indicate that the switch is off. When the armature is in attracted position and the actuator member 30 is in its outwardly projected position as shown in Figure 1, the on marking on the indicator arm 50 is positioned to be viewed through the opening 26 to indicate that the switch is on."

The embodiment of the invention shown in the drawings is for illustrative purposes only, and it is to be expressly understood that said drawings and the accompanying specification are not to be construed as a definition of the limits or scope of the invention, reference being had to the appended claims ior that purpose.

I claim:

1. In combination, a supporting structure, a switch fixedly mounted on said structure provided with a controlling member having an "on" position and on oiT" position, a reset member mounted on said structure for rectilinear movement to reset and released positions, an actuator member mounted on said structure for rectilinear movement to resetting and released positions and cooperable with said reset member, when same is in released position, to reset said reset member to reset position by movement of said actuator member from released position to reset position, said reset member and said actuator member being substantially coaxial, means for holding said reset member in reset position, and an operating arm for actuating said controlling member to on" position by cooperation of said actuator member therewith upon movement of said actuator member from resetting position to released position and only when said reset member is held in reset position.

2. In a switch of the class described, in combination, a supporting structure, a reset member mounted on said structure for rectilinear movement to reset and released positions, an actuator member mounted on said structure for rectilinear movement to resetting and released positions and cooperable with said reset member, when same is in released position, to reset said reset member to reset position by the movement of said actuator member from released position to reset position, said reset member and said actuator member being substantially coaxial, means for holding said reset member in reset position, switch means fixedly mounted on said structure, and a switch operating member actuated to position closing said switch means by cooperation with said actuator member upon movement of said actuator member from resetting position to released position only when said reset member is held in reset position.

3. In combination, a supporting structure, a switch fixedly mounted on said structure provided with a controlling member having an on position and an ofi" position, a reset member mounted for movement to reset and released positions, an actuator member mounted for movement to resetting and released positions and cooperable with said reset member, when same is in released position, said reset member and said actuator member being substantially coaxial, to reset said reset member to reset position by movementof said actuatormember fromreleased position to reset position, means for holding said reset member in reset position, a cam lever pivoted on said reset member, cam means on said actuator member for cooperation with said lever,

and an overtravel spring operating arm carried by said cam lever for actuating said controlling member to on" position by movement of said actuator member from resetting position to released position and only when said reset member is held in reset position.

4. In switch operating means, a supporting structure, an actuator member guided by said structure movable to a resetting position and a released position, a reset stem and guide means therefor, said stem being yieldingly urged toward released position and movable therefrom to reset position, means for releasably holding said stem in reset position, a switch, a switch actuating lever pivoted to said stem for movement therewith and for relative swinging movement into switch closing position and switch opening position, means for moving said reset stem from its released position to its reset position in the movement of said actuator member from its released position to its resetting position, and cam means carried by said lever and said actuator member effective for swinging said lever into switch closing position by movement of said actuator member from its resetting position to its released position when said stem is held in reset position and for swinging said lever into switch opening position by movement of said stem to its released position when said actuator member is in its released position, said cam means being also effective for swinging said lever into switch opening position by movement of said actuator member from its releasing-position to its resetting position when said reset stem is held in its reset position.

5. In switch operating means, a supporting structure, an actuator member guided by said structure having rectilinear movement to a resetting position and a released position, a reset stem and guide means therefor, said stem having rectilinear movement to a reset position and a released position and being yieldingly urged toward its latter position, means for releasably holding said stem in its reset position, a switch, a switch actuating lever pivoted to said stem for relative swinging movement into switch closing position and switch opening position and having a cam slot, means for moving said reset stem from its released position to its' reset position in the movement of said actuator member from its released position to its resetting position, and a cam pin carried by said actuator member and engageable in said slot for swinging said lever about its pivot into switch closing position upon movement of the actuator member to released position when said stem is held in its reset position and swinging said lever into switch opening position upon movement of said stem to released position when said actuator member is in its released position, said pin also being effective for swinging said lever into switch opening position upon movement of said actuator member from its released position to its resetting position when said stem is held in its reset position.

6. In switch operating means, a supporting structure, an actuator member guided by said structure having rectilinear movement to a resetting position and a released position, a reset stem and guide means therefor, said stem having rectilinear movement to a reset position and a released positionand being yieldingly urged toward its latter position, means for releasably holding said stem in its reset position, a switch fixedly mounted on said structure having an operating member movable between on" and off posi- 2,340,197.Har0ld A. Mantz, Milwaukee, Wis. SAFETY SWITCH.

Jan. 25, i944. Disclaimer filed May 22, 1947, by the assignee, Milwaukee Gas Spectalty Company; the inventor assent-mg.

Hereby enters this disclaimer to claims 1 and 2 of said patent.

[Ofiicial Gazette June 17, 1947.]

tions, a switch actuating lever pivoted to said stem and having a cam slot, an arm carried by said lever and cooperating with said operating member to actuate the latter to its on position by swinging movement of said lever to a first position and to its oil position by swinging movement of said lever to a second position, means for moving said reset stem from its released position to its reset position in the movement of said actuator member from its released position to its resetting position, and a cam pin carried by said actuator member and engageable in said slot for swinging said lever about its pivot into its said first position upon movement of the actuator member to released position when said stem is held in its reset position and swinging said lever to its said second position upon movement oi said stem to released position when said actuator member is in its released position, said pin being also effective for swinging said lever into its said second position upon movement of said actuator member from its released position to its resetting position when said stem is held in reset position.

'7. In switch operating means, a supporting structure, an actuator member guided by said structure movable lengthwise to a resetting po sition and a released position and having a forked ill/ll inner end provided with lengthwise slots in its arms, a reset stem substantially coaxial with said actuator member having one end positioned between the arms of the forked inner end of said actuator member and yieldingly urged toward released position, means for releasably holding said stem in reset position, a pin carried by said stem extending through said slots and engageable by the actuator member for moving said stem to reset position by movement of said actuator member to resetting position, a switch actuating lever pivoted to said stem extending between the arms of the forked inner end of said actuator member and having a cam slot, and a cam pin carried by said actuator member and operable in said slot effective for swinging said lever in one direction upon movement of said actuator member from its resetting position to its released position when said stem is held in its reset position and in an opposite direction upon movement of said stem from its set position to its released position when said actuator member is in its released position, said pin also being effective for swinging said lever in its said opposite direction upon movement of said actuator member from its released position to its resetting position when said stem is held in its reset position.

HAROLD A. MANTZ.

DISCLAIMER Patent dated