US2984832A - Electric sounder - Google Patents

Description

y 1961 J. E. GILMAN 3RD, EI'AL 2,984,332

ELECTRIC SOUNDER Filed Dec. 15, 1959 2 Sheets-Sheet 1' INVENTORS JOHN E.G|LMAN 3' Y ROBERT D.GRAF B ROBERT E.PROUTY mam AGENT FIG .4

y 15, 1951 J. GILMAN 3RD., ETAL 2,984,832

ELECTRIC SOUNDER 2 Sheets-Sheet 2 Filed Dec. 15, 1959 mmvrons JOHN E.GILMAN 3" ROBERT D. GRAF BY ROBERT E.PROUTY AGENT United States Patent ELECTRIC SOUNDER John E. Gilrnau, 3rd, Logansport, Robert D. Graf, Flora, and Robert E. Prouty, Logansport, Ind., assignors to Essex Wire Corporation Filed Dec. 15, 1959, Ser. No. 859,724

4 Claims. (Cl. 340392) This invention relates to electric sounders and more particularly to electric sounders of the plunger type which have a slidably mounted striker adapted to strike a sounding element such as a bell.

There are many applications where it is desired to use an electric sounder of the type in which repetitive striking of a sounding element occurs at a low rate such as only five times a minute. An electric sounder of this type has application, for instance, in electric appliances such as automatic washers and dryers to indicate the end of an operating cycle. In the past, the desired low rate of operation has been obtained by actuating the striker by a suitably geared rotary motor or by controlling the operation of an electromagnet plunger mechanism with a timer switch. These arrangements, however, are somewhat expensive and complicated, and as a result, attempts have been made to devise suitable thermally actuated sounders. These thermal-1y actuated sounders have generally employed a bowed bimetallic element which is alternately heated and cooled to provide a snap motion for moving a striker. This invention is concerned with improvements in sounders which are particularly applicable to sounders employing a bowed bimetallic element.

One object of this invention is to provide an improved electric sounder which is relatively simple in construction, economical to manufacture and reliable in operation.

Another object of this invention is to provide an improved electric sounder which will provide clear and loud sounds repetitiously at a low rate.

A further object of this invention is to provide a thermally actuated sounder having an improved striking mechanism.

In the preferred embodiment of the invention hereinafter described, a sounder of the type having a reciprocating plunger adapted to strike a sounding element is provided with a lost motion driving connection between the plunger and the operating element of an electrically energized actuating means by which the plunger is propelled with motion independent of the operating element to strike the sounding element. The lost motion driving connection includes a driving connection between the operating element and the operating member of a switch controlling the energization of the electrical actuating means by which striking motion may be imparted to the plunger before the motion of the switch operating member is impeded by the force required to move the switch operating member to its operated position. More specificall'y, the motion of the operating element in one direction is directly imparted to the switch operating member which in turn propels the plunger in the same direction toward the sounding element. Upon return motion of the operating element, the latter directly engages the plunger to propel it toward another portion of the sounding element. As shown and described herein, the electrical actuating means comprises a bowed bimetallic strip confined under compression between two flexible supports and adapted when heated by a heating coil connected to the switch to snap to an oppo- Patented May 16, 1961 sitely bowed position and when cooled to return to the initial bowed position.

Other objects and features of the invention will be apparent from reference to the following description and accompanying drawings in which:

Fig. 1 is a side view of a thermal-electric sounder embodying the present invention, with the bell shown in section;

Fig. 2 is a sectional view taken substantially along the line 22 of Fig. l, but with the bell illustrated in dotted lines;

Fig. 3 is a sectional view taken substantially along line 3-3 of Fig. 2, but with the bell removed;

Fig. 4 is a sectional view taken substantially along line 44 of Fig. 2, but with the bell removed;

Fig. 5 is a view similar to Fig. 4, but with the parts of the sounder in another operating position; and

Fig. 6 is an exploded view in perspective, illustrating certain parts of the sounder prior to assembly.

Referring to the drawings, the parts of the sounder are carried by a base plate 10 of insulating material to which may be secured a suitable mounting bracket 11 for mounting the sounder upon a wall or panel. Also secured to the base plate 10 is a supporting bracket 12 which is provided with a base portion 13 and and three (3) laterally extending parts 14, 15 and 16. Part 14 has a bent extension 17 to which a spacer 18 and a cuplike bell or sounding element 19 are fastened with a screw 20.

Part 14 of bracket 11 supports a generally U-shaped holder 21 formed of spring material and comprising a pair of arms 22 joined by an intermediate portion 23. Each of the arms 22 is provided an aperture 24 for pivotally supporting the tongued ends 25 of a bowed bimetallic strip or operating element 26. Strip 26 is composed of two (2) thin layers of metal having dilferent coefiicients of expansion and is confined under endwise compression by the flexible arms 22 with the lower expansive layer facing the intermediate portion 23 of holder 21. When strip 26 is heated to predetermined temperature, it Will snap from the bowed position shown in Fig. 2 to the oppositely bowed position shown in Fig. 5. Upon cooling suificiently, the strip 26 will snap back in the opposite direction to the position shown in Fig. 2. To adjust the pressure of arms against the ends of strip 26 to provide the desired snap action of strip 26, an adjusting screw 27 is threaded in part 14 of bracket 12 and bears against the intermediate portion 23 of holder 21.

An electric heating coil 28 is wrapped around strip 26 and has one end connected by lead 29 to the bracket 12 while the other end of heating coil 28 is connected by lead 30 to a terminal 31. Lead 29 is conductively connected through bracket 12 to a fixed contact 32 which is secured to the end of bracket part 15. Contact 32 is arranged to be engaged by a movable contact 33 carried by a resilient metal vane 34. Vane 34 is supported on a post 35 so that it is biased in the position shown in Fig. 2. Post 35 is suitably secured on base plate 10 in electrical connection with terminal 36. In the position of vane 34 shown in Fig. 2, it is apparent that current will flow through lead 30, heating coil 28, lead 29, bracket 12, contact 32, contact 33, vane 34 and post 35 when terminals 31 and 36 are connected to an electric power source.

In order to move the vane 34 to a contact-separating position, a switch-operating member or slide 37 of suitable electrical insulating material is slidably supported in bracket 12. The rectangular end portion 38 of slide 37 is supported for reciprocation in portion 39 of a T-shaped opening 40 formed in bracket part 14 While the other rectangular end portion 41 of slide 37 is supported in the aligned opening 42 formed in bracket part 16. Slide 37 is shaped to provide a straight edge 43 adjacent the base portion 13 of bracket 12 while the opposite portion is provided with an integral projection 44 consisting of a shank portion 45 with an inclined edge 46 and an overhanging shoulder portion 47 forming recess 48. End portion 38 of the slide 37 is arranged to pass freely between the bracket base portion 13 and the adjacent edge of bimetallic strip 26, but edge 49 of shank portion 45 is adapted to be engaged by strip 26. Similarly, end portion 41 of slide 37 is arranged to pass freely between the bracket base portion 13 and the adjacent edge of vane 34 while edge 50 of shoulder portion 47 is adapted to engage a narrow tongue 51 extending from an inner flap extension 52 of the free end of vane 34 within an elonged aperture 53 formed in switch vane 34.

To serve as a striker to be projected against the bell 19, a plunger 54 of suitable electrical insulating material is slidably supported by the bracket 12 for reciprocation in the same directions as the slide 37. The plunger 54 comprises a first end portion 55 and a second end portion 56 of reduced width which is provided with a central slot 57 extending along the longitudinal axis of the plunger from the junction between the end portions. End portion 55 is slidably supported in portion 58 of opening 40 in the bracket part 14 while end portion 56 passes through an aligned opening 59 formed in bracket part 16. End portion 55 also passes freely through an opening 60 formed in holder 21 and shaped to permit assembly of the slide 37 therethrough after holder 21 is fastened to bracket part 14. End portion 56 passes through an opening 61 in bimetallic strip 26 and through aperture 53 of vane 34 while the shoulders 62 defined between end portions 55 and 56 are adapted to be engaged by bimetallic strip 26. The shoulder portion 47 of slide 37 is loosely received in slot 57 of the plunger 54 with the edge 50 being adapted to engage the edge 63 at the end of slot 57.

The operation of the sounder is as follows: Prior to energization of the heating coil 28, the parts of the sounder assume the position shown in Fig. 2 in which the contact 33 is in engagement with contact 32 and a circult is completed to the heating coil 28 from terminals 31 and 36. When a suitable electric power source is connected to the terminals, the bimetallic strip 26 is heated by the heating coil 28 and at a predetermined temperature, reverses its curvature to snapover-center to the oppositely bowed position shown in Fig. 5. As strip 26 moves from its initial position, it engages edge 49 of the slide shank portion 45 and drives slide 37 toward the vane 34 with a snap action. When the strip 26 snaps overcenter, the edge 63 of slot 57 is struck by edge 50 of the slide shoulder portion 47 propelling the plunger end 56 sharply into engagement with the bell 19 with a final movement independent of the motion of either the slide 37 or the strip 26. During movement of the slide 37, the edge 50 of shoulder portion 47 also engages the tongue 51 of vane 34, but not before the plunger 54 is struck by the slide 37 so that the plunger is shifted with a maximum impact force. The slide 37 then deflects the vane 34 to the position shown in Fig. and separates contacts 32 and 33 to interrupt the circuit to the heating coil 28. It is to be noted that the slot 57 is of suflicient length to permit a definite separation between edge 50 of the slide shoulder portion 47 and the edge 63 of the plunger slot 57 so that the plunger 54 is not held against the bell 19 which would deaden the ring of the bell.

Upon heating coils 23 being deenergized, the bimetallic strip 26 begins to cool. After a predetermined time, strip 26 snaps back to its original position shown in Fig. 2. As the strip 26 snaps overcenter, it strikes shoulders 62 of the plunger 54 with an impact which propels the plunger 54 sharply into engagement with another portion of the bell 19 with a final movement that is independent of the motion of strip 26. It is to be noted that after strip 26 has returned to initial position, it does not press against shoulders 62 of plunger 54, which would deaden the ring of the bell 19. During movement of the plunger 54, slide 37 is shifted away from vane 34. It will be apparent that as vane 34 returns contact 33 into engagement with contact 32, vane 34 does not resist the return movement of the plunger 54. Upon reengagement of contacts 32 and 33, heating coil 28 is again energized and this cycle of operation will be repeated as long as terminals 31 and 36 remain energized.

It will be seen from the foregoing description that the shoulders 62 and slot edge 63 of plunger 54 cooperate with edges 49 and 5t) of the slide projection 44 to provide a lost motion driving connection between bimetallic strip 26 and the plunger 54 by which the plunger is propelled in both directions with a motion independent of strip 26 to strike the bell 19. This lost motion driving connection also prevents the switching movement of slide 37 from impeding the striking motion of the plunger 54. This free motion of the plunger 54 is effective to consistently provide clear and loud ringing sounds in both directions of plunger motion. It will also be seen that the sounder can be simply and economically manufactured, but is constructed of sturdy parts to be durable in operation.-

While the invention has been illustrated and described in its preferred embodiment and has included certain details, it should be understood that the invention is not to be limited to the precise details herein illustrated and described since the same may be carried out in other ways falling within the scope of the invention as claimed.

What is claimed is:

1. A thermally actuated sounder comprising, in combination: a sounding element; supporting structure for said sounding element; a thermally responsive snap-acting element carried by said supporting structure and being opera tive when heated to move from a normal position and when cooled to return to normal position; electrically energizable means for heating said thermally responsive element; a circuit for said heating means; switch means including electrical contacts in said circuit for controlling the energization of said heating means; a switch-operating member mounted on said supporting structure for longitudinal movement relative to said thermally responsive element; said switch-operating member being movable between a first position where it permits said switch means to energize said heating means and a second position where it causes said switch means to de-energize said heating means; said switch-operating member having a first portion positioned to be engaged by said thermally responsive element as the latter moves from its normal position; said thermally responsive member driving said switchoperating member from said first position to said second position as said thermally responsive element moves from its normal position; a striker slidably mounted on said supporting structure for longitudinal movement relative to said thermally responsive element for striking said sounding element; said switch-operating member and said striker being movable relative to each other along parallel paths; said switch-operating member having a second portion positioned to engage said striker and drive said striker in one direction toward one part of said sounding element as said switch-operating member moves from said first position to said second position; and said striker being free for continued movement in said one direction after said switch-operating member reaches said second position.

2. A sounder according to claim 1 wherein said striker has a portion positioned to be engaged by said thermally responsive element as the latter returns to its normal position; said thermally responsive element driving said striker in an opposite direction toward a second part of said sounding element as said thermally responsive element returns to its normal position; and said striker being free for continued movement in said opposite direction after said thermally responsive element returns to its normal position.

3. A thermally actuated sounder comprising, in combination: a sounding element; supporting structure for said sounding element; a snap-acting bimetallic strip having end portions by which said strip is mounted upon said supporting structure in a bowed condition; said strip being operative when heated to snap from a normal bowed position to an oppositely bowed position and when cooled to return to said normal position; an electric heating coil for heating said strip; a circuit for said heating coil; switch means in said circuit including relatively fixed and movable contacts; a flexible vane carrying said movable contact and biased to normally urge said movable contact into engagement with said fixed contact; a switchoperating slide slidably mounted on said supporting structure adjacent said strip for longitudinal movement relative to the latter; said slide having a first portion positioned to engage said vane and to move said vane to a contact-separating position as said slide moves from a first position to a second position; said slide having a second portion positioned to be engaged by said bimetallic strip as the latter moves from its normal position; said bimetallic strip driving said slide from said first position to said second position as said bimetallic strip moves from its normal position; a striker slidably mounted on said supporting structure for longitudinal movement relative to said bimetallic strip for striking said sounding element; said slide and said striker being movable relative to each other along parallel paths; said striker being provided with a longitudinal slot; said slide having a part projecting into said slot and longitudinally movable therein; said projecting part of said slide having one edge positioned to engage said striker at one end of said slot and drive said striker in one direction toward said sounding element as said slide moves from said first position to said second position; and said slot having a length sufficient to permit continued movement of the striker into engagement with one part of said sounding element after said slide reaches its second position.

4. A sounder according to claim 3 wherein said striker has a portion positioned to be engaged by said bimetallic strip as the latter returns to its normal position; said bimetallic strip driving said striker in an opposite direction toward a second part of said sounding element as said bimetallic strip returns to its normal position; and said striker being free for continued movement in said opposite direction into engagement with said second part of said sounding element after said bimetallic strip returns to its normal position.

References Cited in the file of this patent UNITED STATES PATENTS 1,980,194 Ford Nov. 13, 1934 2,141,775 Varley Dec. 27, 1938 2,220,979 Swanson Nov. 12, 1940 2,293,671 Alexander Aug. 18, 1942 2,816,280 Detweiler Dec. 10, 1957 2,817,080 Badluman Dec. 17, 1957

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