US2648734A - Safety device - Google Patents

Description

R. J. KUTZLER Aug. 11, 1953 SAFETY DEVICE Filed May 31, 1950 A WF INVENToR 'ROBERT J. KUTZLER MMM ATTORNEY Patented Aug. 11, 1953 SAFETY DEVICE Robert J. Kutzler, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis,v Minn., a corporation of Delaware Application May 31, 1950, Serial No. 165,310

(Cl. 20G-87) 9 Claims.

This invention relates to safety devices in general and, more speciiically, to a safety device for use in a gas heating system for preventing operation of the fuel burning means when an unsafe condition exists.

It is customary in gas heating systems to provide some sort of safety device which is responsive to the presence or absence of a pilot liame to exert a controlling function with respect to the system which will prevent the delivery of fuel to the burner of the system should the pilot burner become extinguished or the gas pressure become so low as to produce dangerous operation of the burner. In recent years, many of the devices which sense the presence or absence of a pilot flame have been thermocouples` or thermopiles which generate enough electricity, when heated by a pilot flame, to sufficiently energize an electromagnet to hold a valve or switch in a position against the bias of a spring to cause the flow of fuel to the main burner. It is this type of control with which the present in vention is concerned.

One of the objects of the invention is to provide an inexpensive yet reliable safety control device that is adapted to be held in its operative position by the amount of current generated by a pilot-burner heated thermocouple.

Another object of the invention is to provide a manually operated safety reset switch having a relatively few parts that are simply yet sturdily assembled.

Another object of the invention is to provide a manually reset switch which makes use of a strip of flexible material to provide theresetting of an armature against an electromagnet while holding an electrical contact out of engagement with a cooperating Contact until the elec'- tromagnet has become energized and the strip has been released.

Still another object of the invention is to provide a simple mechanism for actuation by va l manually operable member to first movea member into engagement with a cooperative holdingV Figure l is a plan view of the device with portions of its elements broken away and with the .l

cover of the device removed;

'slot (not shown) in the arm 22.

2 Figure 2 is a cross-sectional View taken along the line 2 2 of Figure 1;

Figure 3 is an end view of the device with portions of the elements broken away and with the cover removed;

Figure 4 is a fragmentary View similar to Fig? ure 2 but wherein the elements of the device are shown in the positions they would assume in the first step of placing the switch into operating position;

Figure 5 is a fragmentary View similar to thatl of Figure 4 wherein the elements are shown in illustrated and described in the preferred em? bodiment and with the preferred arrangement of its elements.

A mounting or base plate II has laterally extending and transversely offset ears I2 and I3 and transversely and upwardly extending sidev The ears I2 and I3 have an walls I4 and I5. aperture I6 and a slot I1, respectively, to receive mounting screws or bolts for securing the device to a suitable support (not shown). The sidewall i4 has an aperture therein (not shown) which is adapted to receive a coupling unit for BX cable orl other electrical conduit. The wall I5 has a large opening (see Figure 3) which is covered by a Bakelite or other suitable insulating plate I9, carrying conventional electrical connector terminals 20.

Suitably secured to the base II, by means of spot welding or rivets (not shown), is a bracket member 2I having an upwardly and transversely extending arm 22, an upwardly longitudinally extending arm 23, and an upwardly and trans- -=versely extending arm 24 for purposes to be presently described, Secured to the arm 23 by means of a screw 25, is a Bakelite or other electrically insulating panel 26 having a longitudinally extending nger 2'I extending through a vertical It will be noted that the screw 25 will prevent the finger 21 from pulling out of the slot in the arm 22 and that the arms 22 and 23 will thus hold the panel 26 in a rigid vertical or transverse position with respeci;A to the base plate II.

A generally U-shaped bracket 28, made of brass or any other suitable non-magnetic material, is secured to the panel 26 by means of rivets 29. A lower leg 30 of the bracket 28 supports an inverted U-shaped core 3| of an electromagnet by having a bolt 32 pass through an aperture therein, through spacing washers 33 and 34, and through an opening in the base portion of the core member 3 I.

Encircling one of the legs of the U-shaped core member 3|, is a low voltage coil of wire 55 that is adapted to be energized sufficiently by a pilot flame heated thermocouple as to hold the armature 52 against the end of the core against the bias of spring 5d, but insufficient to draw the armature 52 into engagement with the ends of the core against the bias of the spring. The coil is connected by leads 55a and 55h to the two terminal connectors 26 on panel |9. The terminals 26 are connected to the thermocouple A-B by means of internal lead Wires C-D.

Secured to the inner surface of the vertically extending portion of the bracket 28, by means of the rivets 29 that hold said bracket to panel 26, is one leg of an L-shaped adjustment member 35. This members other leg extends substantially parallel with an upper leg 36 of the bracket 28. An adjusting screw 3T extends freely through a hole near the outer end of the member 35 and is screw-threaded through a threaded hole 58 in the outer end of the leg 36. It is thus seen that by adjusting the screw 31, the distance between the leg 36 and the member 35 may be varied for a purpose to be described hereinafter.

An L-shaped terminal bracket 39 is secured to panel 26 by means of rivets 48 and bent-over tines 26a of a well-known terminal connector 28. A leg 39a of the L-shaped bracket 39 extends laterally from the panel 26 in a plane spaced above the plane of the upper ends f the core 3|. One end of a substantially flat or slightly bowed leaf spring 4| is secured to the leg 39a by means of a rivet 42. The leaf Spring is prevented from rotating on the rivet 42 by means of detents 43 struck downwardly from the arm 39a and engaging in notches in the edges of the leaf spring 4|. Substantially centrally of the leaf spring 4| is an enlarged portion fila having a large central opening Mb therein substantially in alignment with the bolt 32 and adjustment screw 3l. The other end 0f the leaf spring 4| has a portion 4|c that is bent outwardly at a slight angle to the adjacent portion of the leaf spring. A conventional Switch contact member 45 extends through a hole in the leaf spring closely adjacent to portion 4|c and is held thereon by riveting the upper end thereof over the top surface of the leaf spring- Positioned directly below contact 45, so as t0 be engaged thereby when the leaf spring 4| swings in that direction, is a Contact 46 riveted to a horizontally extending leg of an L-shaped bracket 4l. Bracket 4l, which is made 0f rigid electrically conductive material, such as brass. is connected to the panel 26 by means of a rivet 4.0 and connector terminal 28 in the same manner as is bracket 39.

Secured to the under side of leaf spring 4|, concentrically with the opening 4|b, is a Bakelite washer 3B having diametrically opposed peripheral recesses 49 (see Figure 4) which receive clamping ears llld extending from the enlarged portion lla of the leaf spring and wrapped around the opposed edges of the Washer 48, through the recesses 49, to Selllely hold 4 the washer 48 to the underside of the leaf spring 4|. A brass sleeve 58, having an enlarged abutment member 5| intermediate itsl` ends, has the upper portion thereof extending.' upwardly through the Bakelite washer llt, and'. a lower portion extending downwardly through. a hole in an armature 52 with a forced fit S0 as to hold the armature 52 tightly against the: A cotter pin: 53 extends downwardly through the sleeve 58,

lower surface of the abutment 5|.

with the loop portion thereof extending above:

the upper end of the sleeve 58 and the tines? thereof extending laterally below the lower end.

of the sleeve 56.

A coil tension spring 54 has a lower hook perf tion which engages the loop of the cotter plflv and an upper hook portion through a pair of spaced holes 35a in adjust-` ment member 35, one of which is broken awas7 in Figure 1 of the drawing.

leaf spring 4|` adjusted by means of the screw 3l' so as to er1-' able such spring to hold the contact 45 out of VVlth thisy engagement with the Contact 63. arrangement, it is obvious that the normal bias of the leaf spring 4| must not be strong inthe direction of bias of spring 54 to enable adjustment of said bias. The bias of spring 4| may be in opposition to spring 54 provided spring 51@ is the stronger.

The means for actuating the armature 52 into surrounds the inner portion of the plunger 6.9

and bears against the inner leg of the bracket 56 and the shoulder 66e to normally urge the plunger 60 outwardly, or to the left as viewed in the figures of the drawing. The plunger isl prevented from being shoved completely out of the bracket 56 by means of a transversely extending portion of the outer end of coil spring 6|, which extends through a hole 66d in the plunger 6E, said end of the spring bearing against the outer leg of the bracket 66 in the normal position of the plunger. The portion 69a limits the inward movement of the plunger 60 by engaging the outer surface of the U- shaped bracket member 56.

A cover 62 has a vertically extending slot 62a adapted to permit the head 68a of the plunger 60 to pass freely therethrough when positionedv on the base plate The sidewalls of the cover are also upwardly recessed from the bottom thereof, to expose the walls I4 and |55 yet corne sufciently close thereto as to prevent dust from getting into the device. The cover is 'held on the base by means of a downwardly and out wardly extending hook portion 63 which lis adapted to extend through a slot Ila in the base Plat@ and hOQk under the bottom surface of the which extends It is thus seen* that the spring 54 will lift the armature 52 away from the core 3| of the electromagnet and hold the upper surface of the abutment 5| against# the under side of washer 48, and tend to lift the The tension 0f the spring 54 is? base plate adjacent said slot. lA hole (not shown) in the other end of the cover 62 enables a screw 64 to pass therethrough and screwthreadedly engage in a threaded hole (not shown) the upwardly extending member 24 on bracket 2|.

Operations With the device described above connected in a heating system, as schematically shown in Figure 1 of the drawing and With the terminal brackets 39 and 41 electrically connected to a suitable control means for a main fuel supply to the burner, the operation of the device is as follows:

After the pilot burner has been ignited by suitable means (not shown), the above described safety device is placed in operative position by shoving the plunger 60 inwardly to cause engagement of the shoulder 60h with the free end of the portion 4|c of leaf spring 4|. Continued movement of the plunger against the bias of spring 6| will cause the leaf spring 4| to buckle downwardly in an obvious manner to cause the elements of the device to assume the positions shown in Figure 4. That is, the armature 52 in engagement with the upper ends of the core 3| of the electromagnet, with the contact 45 still out of engagement with but closer to the contact 46 than in its normal position as shown in Figure 2. Then, if the coil 55 of the electromagnet is suiciently energized, indicating that the ame is of suflicient intensity to cause the thermocouple to provide a sufficient amount of electricity to energize the coil the required amount, a releasing of the plunger 6i) to return to its normal position under the bias of spring 6|, will cause the leaf spring 4| to bias the contact 45 into engagement with contact 46. It will be noted that in this position, the free end of the portion 4|c will be out of alignment with the shoulder 60h so that any subsequent pressing of the plunger 64 will not cause disengagement of the contact 45 from contact 46. The only way that these contacts would separate after the device has been placed in operation, would be by removing the cover and manually moving the contacts apart, or by breaking the circuit to the coil by disconnecting one of the leads to the thermocouple. Of course, the contacts 45 and 46 will separate if the pilot burner becomes extinguished or of such low intensity that the thermocouple will not be heated sufficiently to hold the armature 52, or, in other words, if the device goes into safety operation in the manner in which it is intended. It is thus apparent that the circuit to the controller for the main fuel supply will not be completed unless a pilot iiame is present, as the inward and outward movements of the plunger 60 will merely cause the up and down movements of the armature 52 under the bias of spring 54 unless coil 55 is suiciently energized to hold the armature 52 once it has been engaged by the core 3|. This provides the so-called safety reset of the control device.

While the preferred embodiment of the invention has been described above, a slightly different modiiication of the spring arrangement, as shown in Figure 6, may be satisfactorily used. It will be noted that in this modification, the coil spring 54, member 35, and the upper leg 36 of the bracket 28 is dispensed with and that thev armature 52 is secured to the insulation washer 48 with a spacing washer 1| therebetween by means of a bolt 12 loosely fitting through said members 48, 52 and 1|, witha retaining pin 12a extending through the lower end of they bolt 12. The loose fit of the armature 52 on the bolt 'l2 enables sucient rocking thereof to assure a flat t of the armature 52 on the end of the electromagnet. The leaf spring 4|', on which the Washer 48 is mounted as in the above described modification, is riveted to' an L-shaped bracket I3 as in the modification of Figures 1-5. The bracket I3 differs from the bracket 39 in that it has a laterally extending-and downwardly offset portion 13a through which an adjusting screw I4 extends. It will be observed in this modication that the normal position of the leaf spring 4| must be such that the contact 45 is normally held out of engagement with contact 46 and that the bias of the armature 52 away from the core of the magnet is provided solely by the bias of leaf spring 4|. Therefore, to enable the bias to be calibrated for different dropout voltages, the adjustment screw 'I4 has been provided to vary the upward bias of the spring 4| on the armature 52 when it is in engagement with the electromagnet.

Except for the difference in the details of the spring arrangement, the remainder of the control device is the saine as in the modification of Figures 1-5. Likewise, the resetting or the placing of the device into operating condition is identical to that of the rst described modication.

As indicated above, the illustrated device is merely the preferred form of the invention. It is deemed to be obvious that the arm 4| could carry a Well known bridging contact bar for two spaced contacts similar to the contact 46, instead of a single contact 45; or that the arm could have no contact means but merely be the actuating means for a Well known type of plunger-operated valve which is spring biased to its closed position. In the valve arrangement, the arm 4| would be adjusted to be free of the valve plunger in the positions it assumes in Figures 1 and 4 but would engage and move the plunger to valve open position when it takes the position of Figure 5.

While it will be apparent to those skilled in the art that still other arrangements of the elements of the device and various substitutions of wellknown parts for said elements may be made without departing from the spirit of the invention, it is to be expressly understood that the scope of the invention is to be determined solely from the appended claims.

I claim as my invention:

l. In a safety device, the combination comprising a flexible switch arm having a rst contact on a free end thereof and fixed at its other end, a fixed second contact normally spaced from said rst contact, condition responsive means normally spaced from an intermediate portion of said switch arm and operable to hold said intermediate portion when a predetermined condition exists and said intermediate portion has been moved into engagement therewith, and manually operable means normally biased away from said arm but movable to engage the free end of said arm and to exert a force substantially along the longitudinal axis thereof to iiex the intermediate portion of said arm laterally into engagement with said condition responsive means and thus bias said arm so as to cause said rst contact to move against said second contact when the manually operable means is released from saidarm.-

2. A control'jdevice comprising a control means having a rst member-on one end of a flexible arm which is supported at itsother end, condition responsive means normally spaced from an intermediate portion of said arm and operable to hold said intermediate portion when a predetermined condition exists and said portion has been moved into engagement therewth, a second member of said control means' normally spaced from said firstmember when said' condition does not exist, said second member being held in engagement withsaid first member when said condition exists, and manually operable means having a V-shaped portion thereof for engaging said one end of said arm and exerting a force lengthwise of said arm to cause said intermediate portion of said arm to move into engagement with said condition responsive means while holdingsaid rst member out of engagement with said second member, said manually operable meansibeing biased to free said arm for movement toward said second member under its own bias when it is released.

`3. A control device comprising a control means having a first member near a free end of a movable arm, said free end being laterally oiset from the remainder of said arm, said arm being supported at its other end, a xed second member of said control means, said arm normally biasing said first member against said second member, resilient means biasing said arm and rst member away from said second member, condition responsive means normally spaced from an intermediate portion of said arm and operable to hold said intermediate portion when a predetermined condition exists and said portion has been moved into engagement therewith, and manually operable means for engaging said one end of said arm and exerting a force thereon to cause said intermediate portion of said arm to move laterally into engagement with said condition responsive means against the bias of said resilient means While holding said iirst member in inoperative relationship with respect to said second member, said first member being movable under the bias of said arm to operative position with respect to said secondmember when said manually operable means is released at a time when said condition exists.

4. In combination, a generally arcuate strip of flexible material having one of its ends fixed and the other end thereof free, a rst electrical contact means carried by the free end of said strip, a second fixed electrical contact means cooperable with said first contact means, resilient means acting on said strip and normally biasing said first and second contacts apart, an armature connected to said strip intermediate its ends, an electromagnet energizable by a current generated by a thermocouple heated by a pilot burner name and positioned to be engaged by said armature, and manually operable means normally biased out of engagement with said strip but movable to engage the free end of said strip and to exert a force lengthwise thereof to buckle it into an arc of smaller radius than normal to overpower said resilient means and to cause said armature to engage said electromagnet while holding said first contact means spaced from said second contactmeans, the buckling being such that when the manually operable means is released to return to its normal position and the electromagnet is holding the armature the free end'of the strip willlmovefthe first 8 contact means into engagement with'thel second contact means.

5. In combination, a generally arcuate strip of exible material having one of its ends xed and the other end thereof free, a first electrical contact means carried by the free end of said strip, a second iixed electrical contact means cooperable with said first contact means and normally spaced therefrom, an armature connected to said strip intermediate its ends, an electromagnet energizable by a current generated by a thermocouple heated by a pilot burner flame and positioned to be engaged by said armature, means biasing said strip away from said electromagnet, and manually operable means having a notched portion normally biased out of engagement with said strip but movable on an axis generally parallel to the longitudinal axis of said stripto engage the free end of said strip and to exert a force lengthwise thereof to buckle it into an'arc of smaller radius than normal to cause said armature to engage said electromagnet while holding said rst contact means spaced from said second contact means, the buckling being such that when the manually operable means is released to return to its normal position and the electromagnet is holding the armature the free end of the strip will move the iirst contact means into engagement with the second contact means.

y6. In combination, a substantially flat strip of flexible material having one of its ends fixed and the other end thereof free, said free end having a portion thereof at an angle to the remainder of said strip, a iirst electrical contact means carried by the free end of said strip adjacent said angle portion, a second iixed electrical contact means cooperable with said first contact means and normally spaced therefrom, an armature connected to said strip intermediate its ends, an electromagnet energizable by a current generated by a thermocouple heated by a pilot burner flame and positioned to be engaged by said armature, and manually operable means normally biased out of engagement with said strip but movable to engage the free end portion of said strip and to exert a force lengthwise thereof to buckle it into an arc to cause said armature to engage said electromagnet while holding said first contact means spaced from said second contact means, the buckling being such that when the manually operable means is released to return to its normal position and the electromagnet is holding the armature the free end of the strip will move the first contact means into engagement with the second contact means.

'7. In a safety control device requiring resetting to its operating position after movement to its non-operating position, a holding means comprising a holding member and a held member biased to move away from said holding member and requiring movement to said holding member to again be held thereby after release, a control member having operative and inoperative positions, means connecting said control member and held member together for holding said control member in its operative position when the held member is held by said holding member, means for moving said control member to its inoperative position upon release of said heldv member from said holding member, said connecting means having portions thereof movable relative to each other for normally causing movement of said control device and held member together but permitting such relative movement between them that said held member may be moved to its held position while said control device moves toward but does not reach its operative position, and actuating means positioned to engage said connecting means adjacent said control member for so actuating said connecting means.

8. In a safety control device requiring resetting to its operating position after movement to its non-operating position, a holding means comprising a holding member and a held member biased to move away from said holding member and requiring movement to said holding member to again be held thereby after release, a control member having operative and inoperative positions, means flexibly connecting said control member and held member together for holding said control member in its operative position when the held member is held by said holding member and for moving said control member to its inoperative position upon release of said held member from said holding member, said connecting means normally causing movement of said control device and held member together but providing relative movement therebetween so that said held member may be moved to its held position while said control device moves only part way toward its operative position, and actuating means normally spaced from but movable into engagement with said connecting means adjacent said control device for so actuating said connecting means.

9. In a safety control device requiring resetting to its operating position after movement to its non-operating position, a holding means comprising a holding member and a held member biased to move away from said holding member and requiring movement to said holding 10 member to again be held thereby after release, a control member having operative and inoperative positions, flexible means connecting said control member and held member together for holding said control member in its operative position when the held member is held by said holding member and for moving said control member to its inoperative position upon release of said held member from said holding member, said flexible connecting means comprising elongated arm means having a xed end and a free end, said control member being positioned on said flexible means near said free end, means for applying force to said free end of said arm means generally lengthwise thereof to move the ends of said arm means closer together so that an intermediate portion of said arm means is moved laterally to a greater extent than said control member, said control member being actuated by said free end and said held member being actuated by said intermediate portion whereby said held member may be moved to its held position while said control member is moved toward but not to its operative position, said free end being biased to move said control member to its operative position when said held member is held in its operative position and said force applying means is free of said arm.

ROBERT J. KUTZLER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,676,155 Pfeifer July 3, 1928 1,680,428 Mottlau Aug. 14, 1928 2,014,286 Nelson Sept. 10, 1935 2,515,992 Engholdt July 18, 1950

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