US3905003A

US3905003A - Electrical switch construction and parts therefor

Info

Publication number: US3905003A
Application number: US437334A
Authority: US
Inventors: David M Rosenberg; Siegfried E Manecke
Original assignee: Robertshaw Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1974-01-28
Filing date: 1974-01-28
Publication date: 1975-09-09
Anticipated expiration: 1992-09-09

Abstract

An electrical switch construction having a support carrying a magnet and a movable armature that is attracted by the magnet to tend to move toward the same and thereby engage a fixed contact to complete an electrical circuit. A bimetal member is carried by the armature to move the armature away from the magnet when the bimetal member is heated to a certain temperature and thereby cause opening of the circuit. An electrical heater is carried by the bimetal member for heating the bimetal member when the heater is energized, the heater having opposed ends of which one is secured to the armature to operatively interconnect the bimetal member thereto as well as to provide electrical connection thereto.

Description

United States Patent [191 Rosenberg et al.

[ ELECTRICAL SWITCH CONSTRUCTION AND PARTS THEREFOR Primary Examiner-J. D. Miller Assistant ExaminerFred E. Bell [75] Inventors' Davld Rosenberg .Slegmed Attorney, Agent, or FirmCandor, Candor & Tassone Manecke, both of Indiana, Pa.

[73] Assignee: Robertshaw Controls Company, [57] ABSTRACT Richmond, Va.

An electrical switch construction having a support [22] F'led: 1974 carrying a magnet and a movable armature that is at- [21] A No. 437,334 tracted by the magnet to tend to move toward the same and thereby engage a fixed contact to complete an electrical circuit. A bimetal member is carried by [52] U.S. CI. 337/54; 337/90; 337/98, the armature to move the armature away from 2 337/ 3315 34 2 magnet when the bimetal member is heated to a cer- [51] Int. Cl. /1 tain temperature and thereby cause opening of the [58] Fleld of Search 337/54 cuit. An electrical heater is carried by the bimetal 337/366 member for heating the bimetal member when the heater is energized, the heater having opposed ends of [56] References C'ted which one is secured to the armature to operatively UNITED STATES PATENTS interconnect the bimetal member thereto as well as to 2,870,290 1/1959 Taylor et a1. 337/98 X provide electrical connection thereto. 3,110,789 11/1963 Hild et al. 337/90 X 3,177,316 4/1965 Mertler 337 90 x 23 Clams, 9 Drawing Figures I I 44 59 d 42 64 34 7? i 32 43 66'O 33 5O 67 a 35 76 72 w 62 PATENTEU SEP 9 i975 SHEET 1 UP 3 FUENTES EP 1975 sum 3 [If 3 ELECTRICAL SWITCH CONSTRUCTION AND PARTS THEREFOR This invention relates to an improved electrical switch construction as well as to improved armature arrangements therefor or the like.

It is well known that electrical switch constructions have been provided wherein each has a magnet therein for attracting an armature toward the magnet so that a contact carried by the armature will be moved into contact with a fixed contact to complete an electrical circuit through the switch construction. A bimetal member has been provided for the armature to cause movement of the armature away from the magnet when the bimetal member has been heated to a certain condition whereby the electrical circuit is broken. An electrical heater is provided for the bimetal member to heat the same when the heater is energized, the heater being energized when the circuit is completed and is deenergized when the circuit is open so that the electrical switch construction will cycle on and off as the heater is cycled on and off. The rate of cycling of said switch can be adjusted by a cam means that operates on the armature.

One such electrical switch construction is disclosed and claimed in the US. Pat. to Hild et al, No. 3,1 10,789.

It is a feature of this invention to provide an improved electrical switch construction of the above type.

It is also a feature of this invention to provide an improved armature arrangement for such a switch construction or the like.

In particular, one embodiment of the electrical switch construction of this invention includes a support means carrying a magnet and a movable armature being attracted by the magnet to tend to move toward the same and thereby be placed into contact with a fixed contact. A bimetal member is carried by the support means and is operatively interconnected to the armature to move the armature away from the magnet when the bimetal member is in a certain operating condition thereof. An electrical heater is carried by the bimetal member for heating the bimetal member when the heater is energized, the heater having opposed ends of which one end is secured to the armature to operatively interconnect the bimetal member thereto and to also provide electrical connection thereto. A spring blade has one end thereof secured to the armature and carrying a contact on the other end thereof. The spring blade has a normal bias to hold the other end thereof against one side of the armature in a direction away from the magnet. The armature has an opening passing therethrough and the other end of the blade has a tang projecting through the opening and being disposed adjacent the other side of the armature in spaced relation relative thereto but in the path of movement thereof for contact weld breaking purposes.

Accordingly, it is an object of this invention to provide an improved electrical switch construction having one or more of the novel features set forth above or hereinafter shown or described.

Another object of this invention is to provide an improved armature arrangement for an electrical switch construction or the like, the annaturc arrangement of this invention having one or more of the novel features set forth above or hereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from a reading of this description, which proceeds with reference to the accompanying drawings forming a part thereof and wherein:

FIG. 1 is a front, perspective view of the improved electrical switch construction of this invention.

FIG. 2 is an enlarged, front view of the switch construction of FIG. 1 with the front cover means thereof removed, FIG. 2 illustrating the switch construction in its off" condition.

FIG. 3 is a cross-sectional view taken on line 3-3 of FIG. 2.

FIG. 4 is a view similar to FIG. 2 and illustrates the switch construction in one of the operating positions thereof.

FIG. 5 is a fragmentary view similar to FIG. 4 and illustrates the switch construction in another operating condition thereof.

FIG. 6 is a view similar to FIG. 5 and illustrates the switch construction in still another operating condition thereof.

FIG. 7 is an exploded perspective view of the improved armature arrangement for the switch construction of FIG. 1.

F IG. 8 is a front view of part of the armature arrangement and is taken in the general direction of the arrows 88 of FIG. 7.

FIG. 9 is a view similar to FIG. 8 and is a rear view of the part of the armature arrangement of FIG. 8.

Referring now to FIGS. 1 and 2, the improved electrical switch construction of this invention is generally indicated by the reference numeral 10 and comprises a housing means or support means 1 1 formed from a generally 'rectangularly cup-shaped housing member 12 having its open end 13 closed by an intermediate cover member 14 and an outer casing cover 15 detachably secured thereto by tongues 16 in a manner well known in the art whereby a switch chamber 17 is provided in the housing means 1 1. The

housing parts

12 and 14 are formed from any suitable electrically insulating material.

A pair of

fixed contacts

18 and 19 are respectively disposed in the switch chamber 17 and supported therein by

conductive terminal members

20 and 21 carried by the housing means 1 1 and having parts projecting from the rear thereof in the manner illustrated in FIG. 1 for external lead attachment purposes.

A pair of

movable contacts

22 and 23 are respectively provided for cooperating with the

fixed contacts

18 and 19 in a manner hereinafter described.

The movable contact 23 is carried on a terminal arm 24 which is relatively flexible and is carried by the housing means 11 so that a part thereof extends from the rear of the housing 11 in the manner illustrated in FIG. 1. The terminal part 24 is bent to provide an elbow 25 thereof which is adapted to be normally biased against a cam surface 26 of a rotatable cam member 27 disposed in the switch chamber 17 and being rotatably mounted on a shaft 28 which projects out of the front of the switch housing 11 in the manner illustrated in FIG. 1 for a purpose hereinafter described.

The cam surface 26 of the cam member 27 has a recess 29 therein so when the elbow 25 of the terminal blade 24 is received in the recess 29 in the manner illustrated in FIG. 2, the natural bias of the blade 24 has moved the movable contact 23 out of contact with the fixed contact I9 as illustrated in FIG. 2. However,

when the cam member 27 is rotated so that the elbow 25 of the terminal blade 24 is no longer in the recess 29, the cam surface 26 maintains the movable contact 23 into contact with the fixed contact means 19 in the manner illustrated in FIG. 4.

The other movable contact 22 comprises part of the improved armature arrangement of this invention that is generally indicated by the reference numeral 30 and will now be described.

The armature arrangement 30 includes a flat platelike armature 31 of conductive material and having a hinge member 32 riveted by rivets 33 thereto at the lower end 34 thereof, the hinge member 32 having a pair of depending arms 35 each provided with an opening 36 passing therethrough to loosely receive a shaft member 37 that is rotatably mounted in suitable recesses (not shown) in the subcover member 14 and the closed end wall 38 of the cup-shaped housing member 12 in the manner illustrated in FIG. 3.

The shaft 37 so mounts the armature 31 that the upper end 39 of the armature member 31 is disposed closely adjacent a permanent magnet 40 carried by the support means 1 1 adjacent the fixed contact 18 so that when the armature 31 is free to move, the same is attracted toward the magnet 40 in the manner illustrated in FIG. 4 and the armature 31 pivots on the shaft 37 to permit the movable contact 22 to be disposed in contact with the fixed contact 18 in the manner illustrated in FIG. 4 as will be apparent hereinafter.

The contact 22 is carried on an upper end 41 of a spring blade 42 having its lower end 43 secured to the lower end 34 of the armature 31 by the rivets 33 whereby the upper end 41 of the spring blade 42 is adapted to move relative to the armature 31 as will be apparent hereinafter. However, the natural bias of the spring blade 42 is to hold the contact 22 and the blade 42 flat against the side 44 of the armature blade 31 in the manner illustrated in FIG. 2.

The upper end 41 of the spring blade 42 has a bent tang 45 thereof that projects through an opening 46 in the upper end 39 of the armature blade 31 and is spaced from the side 47 of the armature plate 31 in the manner illustrated in FIGS. 2 and 4 to provide for contact weld breaking purposes as will be apparent hereinafter and as illustrated in FIG. 5.

A bimetal member or strip 48 is welded or otherwise secured at the lower end 49 thereof to another bimetal strip 50 at its end 51 with the assembly of the

bimetal strips

48 and 50 being welded or otherwise secured to the shaft 37 in the configuration illustrated. The bimetal member 48 is for controlling movement of the armature 31 relative to the magnet 40 in the manner hereinafter described and the bimetal member 50 is for ambient temperature compensating purposes.

As illustrated in FIG. 7, a strip of high temperature micapaper 52, sold under the trade name Isomica by the Mica Insulator Co., with good electrical insulating properties is disposed against the side 53 of the bimetal strip 48 and has an upper end 54 bent over the upper end 55 of the bimetal member 48. Thereafter, an electrical strip heater 56 is disposed against the insulation strip 52 at the side 53 of the bimetal member 48 and its upper end 57 bent over the top 55 of the bimetal member 48 and outwardly turned to provide a flange 58 which is subsequently welded or otherwise secured to the upper end 39 of the armature 31 in the manner illustrated in FIG. 2 to provide the sole means for operatively interconnecting the bimetal member 48 to the armature plate 31 as will be apparent hereinafter.

Another strip of high temperature micapaper 59 of good electrically insulating properties is disposed on top of the strip heater 56, the strips of

insulation

52 and 59 being wider than the heater 56 as illustrated. Thereafter, a plurality of staple-like members or clamps 60 are disposed around the assembly to firmly hold the various parts thereof in the completed stacked arrangement illustrated in FIGS. 2, 8 and 9.

The lower end 61 of the strip heater 56 is looped upon itself to define a loop 62 to telescopically receive an end 63 of a lead 64 that has its other end 65 interconnected to a terminal member 66 whereby it can be seen that the terminal 66 is, in effect, electrically interconnected to the movable contact 22 through the lead 64, heater strip 56, armature plate 31 and spring blade 42 so so that when the movable contact 22 is disposed against the fixed contact 18 in the manner illustrated in FIG. 4, the

terminal parts

66 and 20 are electrically interconnected together for completing an electrical circuit through the switch construction 10 while at the same time causing electrical current to flow through the heater 56 for a purpose hereinafter described.

A cam follower 67 is carried on a leaf spring 68 that has its end 69 spot welded to a base 70 of the housing means 11 in a cantilevered manner so that the natural bias of the leaf spring 68 is to move the end 71 thereof upwardly in FIG. 2 to maintain an elbow 72 of the cam follower 67 in engagement with a cam surface 73 of the cam member 27.

A threaded adjusting member 74 is carried by the cam follower 67 and has its end 75 abutting against the free end 76 of the bimetal strip 50 in the manner illustrated in FIG. 2. Thus, when the cam member 27 is turned to the position illustrated in FIG. 2 so that the elbow 72 of the cam follower 67 is moved into a recess 77 of the cam surface 73 by the force of the leaf spring 68, such action of the cam follower 67 on the bimetal member 50 causes the armature assembly 30 to pivot in a counterclockwise direction in FIG. 2 in opposition to the attracting force of the magnet 40 to hold the movable contact 22 out of contact with the fixed contact 18 so that no electrical circuit can be completed between the

terminal parts

66 and 20. At such time, the elbow 25 of the terminal blade 24 is also received in the recess 29 of the cam surface 26 so that the movable contact 23 is held out of contact with the contact 19 so that the switch construction 10 is dis posed in its off condition when the cam member 27 is disposed in the position illustrated in FIG. 2.

However, oncethe cam member 27 is rotated so that the

elbows

72 and 25 respectively ride out of the

recesses

29 and 77 to be acted upon by the

respective cam surfaces

26 and 73, the cam follower 67 is moved downwardly from the position illustrated in FIG. 2 to the position illustrated in FIG. 4 to thereby permit the armature assembly 30 to move in a counterclockwise direction under the attracting force of the magnet 40 for the armature plate 31 and place the movable contact 22 into contact with the fixed contact 18 while the movable contact 23 is also moved into contact with the fixed contact 19.

The operation of the electrical switch construction l0 of this invention will now be described.

When the operator turns the cam 27 to an on position thereof as illustrated in FIG. 4 so that the

elbows

25 and 72 are moved outwardly relative to the shaft '28 to respectively place the

movable contacts

22 and 23 against the fixed

contacts

18 and 19 as illustrated in FIG. 4, not only is an electrical circuit provided between the

terminal parts

21 and 24, but also an electrical circuit is provided between the

terminal parts

66 and 20 as previously described.

However, as the current flows through the strip heater 56, the same begins to heat the bimetal member 48 in such a manner that the bimetal member 48 tends to warp to the left in FIG. 5 and when such warping force of the bimetal member 48 is such that the same tends to overcome the attracting force of the magnet 40 for the armature plate 31, the bimetal member 48 is adapted to move the armature 311 with a snap-action in a counterclockwise direction to abruptly move the movable contact 22 away from the fixed contact 18 and thereby open the circuit between the

terminals

66 and 20.

During such initial opening movement of the movable contact 22 away from the fixed contact 18, it may be that a contact weld situation has occurred between the movable contact 22 and the fixed contact 18 wherein the movable contact 22 is held against the fixed contact 18. Thus, the snapping movement of the armature 31 away from the magnet 40 permits a lost motion to be taken up between the armature 31 and the tang 45 of the contact blade 42 in the manner illustrated in FIG. 5 until such time that the armature 31 hits against the tang 45 as illustrated in FIG. 5 whereby a hammer-like blow is thus created against the blade 42 in a contact opening direction to thereby unweld the welded condition between the movable contact 22 and fixed contact 18 so that the movable contact 22 can thereby be moved away from the fixed contact 18 as the armature 31 moves to the left in the manner illustrated in FIG. 6.

The movable contact 22 is held away from the fixed contact 18 until the bimetal member 48. cools sufficiently so that the attracting force of the magnet 40 is again adapted to move the armature 31 toward the magnet 40 and thereby place the contact 22 into contact with the fixed contact 18.

In this manner, it can be seen that the contact 22 will be cycled between its open condition and its closed condition and thereby cycle the circuit between the

terminals

66 and 20 in a like manner.

In order to adjust the timing of the opening and closing cycle of the movable contact 22 with the fixed contact 18, the cam member 27 is rotated so that the desired portion of the cam surface 73 acts on the cam follower 67 to thereby vary the amount of force required for the magnett 40 to attract the armature 31 thereto as is well known in the art.

For further details of the switch construction and the operation thereof, see the aforementioned US. Pat. to Hild et al, No. 3,1 l0,789, as the features of this invention have been fully described in connection with the improved armature arrangement 30 for such a switch construction or the like.

Therefore, it can be seen that this invention not only provides an improved electrical switch construction 10, but also this invention provides an improved armature arrangement 30 for such a switch construction 10 or the like.

While the form of the invention now preferred has been described and illustrated as required by the Patent Statute, it is to be understood that other forms can be utilized and still come within the scope of the appended claims. I

What is claimed is:

1. An electrical switch construction comprising a support means carrying a magnet, a movable armature being carried by said support means and being attracted by said magnet to tend to move toward the same, an electrical contact of said switch construction being carried by said armature to be moved thereby, a bimetal member carried by said support means and being operatively interconnected to said armature to move said armature away from said magnet when said bimetal member is in a certain operating condition thereof, and an electrical heater carried by said bimetal member for heating said bimetal member when said heater is energized, said heater having opposed ends, one of said ends of said heater engaging and being secured to said armature to operatively interconnect said bimetal member thereto. strip 2. An electrical switch construction as set forth in claim 1 wherein said heater comprises a metal strip having said opposed ends..

3. An electrical switch construction as set forth in claim 2 and including a lead carried by said support means and having an end interconnected to the other end of said heater.

4. An electrical switch construction as set forth in claim 3 wherein said other end of said heater is looped and receives said end of said lead in said loop thereof.

5. An electrical switch construction as set forth in claim 2 and including a strip of electrically insulating material disposed between said bimetal member and said heater strip.

6. An electrical switch construction as set forth in claim 5 and including another strip of electrically insulating material covering said heater strip on the side thereof that faces away from said bimetal member.

7. An electrical switch construction as set forth in claim 1 and including a spring blade having opposed ends, one of said ends of said blade being secured to said armature, said contact being carried on the other end of said blade.

8. An electrical switch construction as set forth in claim 7 wherein said spring blade has a natural bias to hold said other end thereof against one side of said armature in a direction away from said magnet.

9. An electrical switch construction as set forth in claim 8 wherein said armature has an opening passing therethrough, said other end of said blade having a tang projecting through said opening and being disposed adjacent the other side of said armature in spaced relation relative thereto but in the path of movement thereof for contact weld breaking purposes.

10. An electrical switch construction comprising a support means carrying a magnet, a movable armature being carried by said support means and being attracted by said magnet to tend to move toward the same, means carried by said support means and being operatively interconnected to said armature to move said armature away from said magnet, a spring blade having opposed ends, one of said ends of said blade being secured to said armature, and a contact being carried on the other end of said blade whereby said other end of said blade is movable relative to said armature, said spring blade having a natural bias to hold said other end thereof against one side of said armature in a direction away from said magnet.

11. An electrical switch construction as set forth in claim 10 wherein said armature has an opening passing therethrough, said other end of said blade having a tang projecting through said opening and being disposed adjacent the other side of said armature in spaced relation relative thereto but in the path of movement thereof for contact weld breaking purposes. I

12. An armature arrangement for an electrical switch construction that has a support means carrying a magnet, said armature arrangement comprising a movable armature adapted to be carried by said support means and be attracted by said magnet to tend to move toward the same, a bimetal member carried. by said armature and being adapted to move said armature away from said magnet when said bimetal member is in a certain operating condition thereof, and an electrical heater carried by said bimetal member for heating said bimetal member when said heater is energized, said heater having opposed ends, one of said ends of said heater being secured to said armature to operatively interconnect said bimetal member thereto.

13. An armature arrangement as set forth in claim 12 wherein said heater comprises a metal strip having said opposed ends. 7

14. An armature arrangement as set forth in claim 13 and including a lead adapted to be carried by said support means and having an end interconnected-to the other end of said heater. 7

15. An armature arrangement as set forth in claim 14 wherein said other end of said heater is looped and receives said end of said lead in said loop thereof.

16. An armature arrangement as set forth in claim 13 and including a strip of electrically insulating material disposed between said bimetal member and said heater strip.

17. An armature arrangement as set forth in claim 16 and including another strip of electrically insulating material covering said heater strip on the side thereof that faces away from said bimetal member.

18. An armature arrangement as set forth in claim 12 and including an electrical contact carried by said armature.

19. An armature arrangement as set forth in claim 18 and including a spring blade having opposed ends, one of said ends of said blade being secured to said armature, said contact being carried on the other end of said blade.

20. An armature arrangement as set forth in claim 19 wherein said spring blade has a natural bias to hold said other end thereof against one side of said armature in a direction away from said magnet.

21. An armature arrangement as set forth in claim 20 wherein said armature has an opening passing therethrough, said other end of said blade having a tang projecting through said opening and being disposed adjacent the other side of said armature in spaced relation relative thereto but in the path of movement thereof for contact weld breaking purposes.

22. An armature arrangement for an electrical switch construction that has a support means carrying a magnet, said armature arrangement comprising a movable armature adapted to be carried by said support means and be attracted by said magnet to tend to move toward the same, a spring blade having opposed ends, one of said ends of said blade being secured to said armature, and a contact being carried on the other end of said blade whereby said other end of said blade is movable relative to said armature, said spring blade having a natural bias to hold said other end thereof against one side of said armature in a direction away from said magnet.

23. An armature arrangement as set forth in claim 22 wherein said armature has an opening passing therethrough, said other end of said blade having a tang projecting through said opening and being disposed adjacent the other side of said armature in spaced relation relative thereto but in the path of movement thereof for contact weld breaking purposes.

Claims

1. An electrical switch construction comprising a support means carrying a magnet, a movable armature being carried by said support means and being attracted by said magnet to tend to move toward the same, an electrical contact of said switch construction being carried by said armature to be moved thereby, a bimetal member carried by said support means and being operatively interconnected to said armature to move said armature away from said magnet when said bimetal member is in a certain operating condition thereof, and an electrical heater carried by said bimetal member for heating said bimetal member when said heater is energized, said heater having opposed ends, one of said ends of said heater engaging and being secured to said armature to operatively interconnect said bimetal member thereto. strip

2. An electrical switch construction as set forth in claim 1 wherein said heater comprises a metal strip having said opposed ends.

11. An electrical switch construction as set forth in claim 10 wherein said armature has an opening passing therethrough, said other end of said blade having a tang projecting through said opening and being disposed adjacent the other side of said armature in spaced relation relative thereto but in the path of movement thereof for contact weld breaking purposes.

12. An armature arrangement for an electrical switch construction that has a support means carrying a magnet, said armature arrangement comprising a movable armature adapted to be carried by said support means and be attracted by said magnet to tend to move toward the same, a bimetal member carried by said armature and being adapted to move said armature away from said magnet when said bimetal member is in a certain operating condition thereof, and an electrical heater carried by said bimetal member for heating said bimetal member when said heater is energized, said heater having opposed ends, one of said ends of said heater being secured to said armature to operatively interconnect said bimetal member thereto.

13. An armature arrangement as set forth in claim 12 wherein said heater comprises a metal strip having said opposed ends.

14. An armature arrangement as set forth in claim 13 and including a lead adapted to be carried by said support means and having an end interconnected to the other end of said heater.