US2094199A - Switch - Google Patents

Description

Sept. 28, 1937.

c. J. WERNER SWITCH Filed July 25, 1934 3 Sheets-Shee?I l Sept 28, 1937- n C. J. WERNER 2,094,199

SWITCH Filed July 25, 1934 3 Sheets-Sheet 2 (9g INVENTOR zw/nf wlw/yf@ ATTORN EYS SWITCH Filed July 25, 1934 3 Sheets-Sheet 3 l N V E N TOR CA'fw//f J. Wig/yf@ Patented Sept. 28, 1937 PATENT OFFICE SWITCH Calvin J. Werner, Dayton, Ohio, as sgnor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application July 25, 1934, Serial No. '136,832

12 Claims.

This invention relates to improvements in electric switches and particularly to electric switches adapted to be actuated automatically in response to temperature changes.

It is among the objects of the present invention 'to provide a switch which is adapted to be operated automatically to open an electric circuit in response to an increased temperature caused by abnormal flow of current through the switch.

A further object of the present invention is to provide an automatically controlled electric switch, the contacts of which cannot be engaged while the high temperature, which causes the switch to be moved automatically to circuit breaking position, exists.

A still further object of the present invention is to provide an electric switch which is adapted to be actuated automatically to circuit-breaking position in response to a predetermined rise in temperature and which cannot be tied or fastened in the circuit-making position by any means separate from the switch.

Another object of the present invention is to provide a switch with means for preventing short circuiting lm from building up on the insulated walls of the switch housing adjacent its contacts.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a front view of the switch mechanism in position within a terminal box.

Fig. 2 is a fragmentary sectional view taken substantially along the line 2-2 of Fig. 1.

Fig. 3 is an enlarged fragmentary sectional view taken substantially along the line 3-3 of Fig. 1.

Fig. 4 is a detail sectional view taken substantially along the line 4-4 of Fig. 1 and showing an ordinary thermostatically controlled switch.

4 Fig. 5 is a detail view of the electro-magnet and the movable contact of the main switch.

Fig. 6 is a view somewhat similar to Fig. 4 illustrating the improved thermostatically controlled switch. In this view the switch is in full contact-making position.

Fig. '7 is a view taken substantially along the line 1-1 of Fig. 6.

Fig. 8 is a fragmentary part sectional view somewhat like Fig. 6, showing the switch mechanism in normal inoperative position.

Fig. 9 is a fragmentary view showing portions of the switch in fullinperated position and the actuator in the position into which manual force will move it if applied after the switch has been engaged by the thermostatic detent.

Fig. 10 is a diagrammatic view showing the switch and its electrical circuit.

Referring to the drawings, the numeral designates a terminal box in which the switch is mounted. This terminal box has a back plate 2l and a hinged door 22, opening of which renders the switch accessible. lo

The switch comprises a housing 23, made of any suitable insulating material, said housing having front and back walls 24 and 25 respectively, partitions between said front and back walls providing compartments within the switch housing, certain of these compartments being designated in the Fig. '1 by the numerals 2G and 21. It will of course be understood that the num--y ber of compartments is dependent upon the number of switch contacts to be provided by the switch. In the present instance, for a two-phase machine which is to be controlled by this switch, six compartments are provided, four, similar to the compartment 26, in which the switch contacts are housed, and two, similar to compartment 21, in which the thermostatically controlled switches are housed. A bracket 3U is secured to the front and back walls of the housing 23 by screws 32 and 33 respectively, said bracket having the mounting plate 34 attached thereto in any suitable manner, a rubber shock-absorbing element 35 being interposed between the bracket 30 of the switch housing and the mounting plate 34.

' This mounting plate has slotted openings which are adapted to receive stud heads carried by the terminal box 20 so that the switch may easily be attached to said box.

Bracket 30 has spaced, depending ears 31 between which the laminated polepiece 38 is rigidly supported. Associated with the polepiece 38 is an electro-magnet coil 40, held in position on the polepiece by wire clamps 4| which are hingedly attached to the bracket 30 as at 42.

The electro-magnetic coil is adapted to be energized to actuate an armature which has a support carrying the movable contacts or bridging elements of the main switch. This armature is T-shaped, being designated by the numeral 45. It is made up of a plurality of stacked laminations, secured together by rivets 49 which pass through aligned openings I9 in the laminations of the armature, said openings being of greater diameter than the rivets. The laminations are not tightly riveted together, but may move relatively to each other so that the faces 50 of the laminations of the armature, when engaging the adjacent laminated ends of the associated polepieces, may align themselves with the respective laminations of said polepieces so as to avoid air gaps at these points, which practically eliminates humming while the armature is in attracted position. The main or central stem of the T-shaped armature, designated by the numeral 5|, extends into and through the central opening in the electro-magnet coil and has the carrier 52 attached thereto in any suitable manner. This carrier supports the movable contacts or bridging elements of the main switch, as has been mentioned before. In the present drawings four such movable contacts or bridging elements are shown, and inasmuch as all are alike, only one Awill be described detailedly.

'I'he movable contact comprises an insulating barrel 55 secured to the carrier 52. The outer end of this barrel is recessed to receive a nut 56 into which one end of the cone-shaped standard 51 is screw-threaded. The bridging element or movable contact 6D i'lts about the cone-shaped standard 51, the opening in said bridging element being of such a size that it cannot pass the flanged head 58 of the cone-shaped standard. A spring 6l, interposed between the nut 56 and the mov- ,able contact or bridging element 60, normally urges said contact toward and against the flanged head 58 of the cone-shaped standard 51. When the armature is unattracted, the bridging element 6D is out of engagement with the stationary contact terminals 63 and 66 secured to the front and back walls 29 and 25" respectively, of the housing. However, when the armature is attracted by the electro-magnet coil and is moved upwardly, the bridging element 68 is moved into contact engagement with the stationary contact terminals 63 and 66 as shown in Fig. 2, the spring 6i being compressed under these circumstances. Deenergization of the electro-magnetic coil releases the armature and, as said armature drops, the flanged head 56 of the standard 51 engages the movable contact or bridging element 68 with a hammer-blow effect, resulting in a quick suparation of the contacts.

n Referring to Figs. 2 and '1, it will be seen that the surface of the partition walls 10 h'ave spaced grooves 1l provided therein adjacent the contacts, or more particularly between the two stationary Contact elements 63 and 64. By experience it has been found that, after comparatively long operation of `a switch of this type, a film will form on the wall of the housing adjacent the contacts due to arcing, this film being of a metallic character and eventually providing a conductor between the twostationary contacts, which will cause short circuiting of the switch. The slots 1I between the two terminals provide inacce'ssible-corners in which this film cannot build up and consequently, although a iilm does laccumulate, there'will be breaks inthe film which breaks prevent a continuous conductive iilrn between the stationary terminals, thus eliminating the danger of short circuits. The Ystationary terminals 68 and 64 in this instance are secured to their respective walls by terminal screws 115 and 116 respectively. v A

One feature of the present invention resides in Athe thermostatically controlled switch which controls the main switch just'described. As has been mentioned heretofore, the thermostatic switch is provided in the end compartment of the insulated switch housing, the one compartment being shown in Fig. 7 and designated by the numeral loaded trigger 19 when it is engaging the thermostatic detent 15. 'Ihe thermostatic detent 15 is heated to i'lex and release the trigger 1li by a heating element 16 which surrounds. a stud 11 carried by the switch housing and in thermal contact with the thermostatic element 15. Terminal posts 18 and 19 are provided for the heating element 16.

In the improved thermostatic switch shown particularly in Figs. 6, 7, 8, and 9, the bi-metallic thermostatic element 15, the heating element 16 and its stud 11 as well as the heating element terminals 18 and 19 are` exactly like the structure shown in Fig. 4. This improved structure also includes the trigger 16 of the structure shown in Fig. 4. 'I'his trigger is pivotally supported by the pin and is constantly urged clockwise toward the stop 8 I, provided by the switch housing, by a spring 82. In this improved construction the stationary terminals 89 and 84, adapted to be bridged by the movable contact element 85, are attached to the switch housing by terminal posts i83a and. |88 respectively, which terminal posts are best shown in Figs. 1 and 10. The movable contact 85 is iloatingly supported in aslot 86 provided in the actuator 81. As shown in Figs. 6, 8, and 9 this slot terminates short of y both ends of this actuator. The movable contact has one end 89 substantially in constant pivotal engagement with the stationary contact 88 as shown in Fig. 8. At this end of the movable contact aprojection 90 is provided which is adapted to cooperate with a wedge-shaped flange 9| on the actuatorA 81', for purposes to be described. Theend 92 of the movable contact is adapted to engage the stationary contact 83 tov bridge contacts 83- and 84. A spring 94 is interposed between the wedge-shaped iiange 9| of the actua? tor andthe movable contact 85. A oating cam element 95 is located within the slot 86 of the actuator, one end oi said i'loatingcam element being adapted to engage the movable contact 85 l the normal oi position of the switch, as shown.

in Fig. 8, it will be seen vthat the rear end walls f of the elongated notches 96 of the actuator 81 engage the trigger 16 due to the action of the spring 98 urging the actuator 81 forward. In the normal oi position asshown in Fig. 8, spring 82 yieldably holds the trigger against the stop 8l.. When manual pressure is exerted upon the actuator 81 to move it inwardly, the actuator moves relatively to the trigger a distance equal to the A`distance between the rear end andthe front end walls of notches 96 or until the Afront end walls of said notches engage the trigger, after which the trigger will be moved counter-clockwise about' its pivotal pin 88 by the movement of the actuator 81 toward contact closing position. During this time the oating cam 95 has its respective ends engaging the movable contact 85 and the trigger 14 and thus the movable contact 85 will be held, from engagement withthe stationaryv to bridge contacts 83 and 84.

contact 83, and will only partially pivot about its resting end 89. The continued movement of the actuator 81 toward the contact-making position will eventually bring the trigger 14 over and behind the end ofthe bi-metallic detent 15 as shown .in Fig. 6. However, at this time the projection on the movable contact 85 will have engaged the sloping surface of the wedge-shaped iiange 91 so that continued movement of the actuator 81 toward the contact closing position, after the trigger has engaged the detent 15, will act to pivot the movable contact 85 about its resting end 89 to move its end 92 a greater distance away from the stationary contact 83. Thus it may be seen that while the actuator is moving the trigger 14 toward its detent-engaged position, the floating cam will prevent the movable contact 85 from having its end 92 engage the stationary terminal 83, and continued movement of the actuator thereafter will bring the wedge-shaped flange 91 into effect, as shown in Fig. 9, to move the end 92 of the movable contact 85 farther away from the stationary terminal 83. Thus it may be said that while the actuator is being movedtoward contact-making position and while manual pressure is being exerted upon said actuator, movable contact 85 cannot engage stationary contact 83 However, when manual pressure on the actuator is released after the'trigger 14 has been moved into engagement with the thermostatic detent 15, then the spring 94 may become effective to move the actuator forwardly through a distance equal to the length of the notches 96 in actuator 81, so that the rear ends of4 notches 96 of the actuator again engage the trigger. Because the effective length of the floating cam is less than the distance between the trigger and the closed contact, the floating cam 95 is ineffective to hold the movable contact 85 out of contact-engaging position and the release of pressure upon the actuator permits the spring 94, which is considerably weaker than spring 82, to move the movable contact 85 about its resting end 89, so that its end 92 engages theL stationary terminal 83 as shown in Fig. 6. Thus contacts 83 and 84 may be bridged only upon release of the actuator after it has moved the trigger 14 into locking engagement with the detent 15.

From the aforegoing it may be seen that if the actuator 81 were retained in the position as shown in Fig. 6, in,which the movable contact bridges contacts 83 and 84, and if the thermostatic detent 15 were flexed to release trigger 14,I

then the spring 82, moving the trigger 14 clockwise, and being considerably stronger than spring 94, would cause said trigger to move the floating cam 95 forwardlyso that its front end would engage the movable contact 85 and'thus move said contact about its resting point 89 to disengage its end 92 from contact 83. It may also be seen that this construction absolutely renders the switch incapable of being tied in such a position in Whichcontact 85 would bridge contacts 83 and 84, for it is absolutely necessary entirely to release the actuator 81 after it has moved the trigger into the position as shown in Fig. 6, in which it engages the detent 15, in order to permit the movable contact 85 to bridge contacts 83 and 84. Thus the destructive practice of tying a protective switch of this kind in its operative position, even when the system demands that the switch b e opened for protective purposes, is substantially impossible with this structure.

Referring now to the Fig. 10 in which a twophase circuit is depicted, the numeral 100 desig- `two lines and 125. Line 105 has a terminal 183 which is connected with a stationary contact 63a-, adapted to be connected to stationary contact 64a by the bridging element 60a. The stationary contact 64a is connected with terminal 101' which in turn is connected with a continuation of line 105. Terminal 183 is in direct electrical connection with the stationary contact 283 of the thermostatically controlled switch, while the other stationary contact 284 thereof is connected with the terminal 184.

The line has a terminal 115 which is connected with the stationary contact 63 of the main switch, adapted to be connected to the stationary terminal 64 by the bridging element 60. Stationary contact 64 is connected with a terminal 19 of heater coil 16, the other end of the heater CFI as has been mentioned is connected by terminal 183 to 'the stationary contact 63a of the main switch. The other line connectible with line |86 by the manually controlled switch 136 has a termina-l 131 connected with the stationary contact 83 of Vthis thermostatic switch which is adapted to be connected with stationary terminal 84 by the movable contact 85 whose actuator is designated by the numeral 81. In this thermostatic switch the trigger is designated by the numeral 14, the trigger spring by the numeral 82, the detent by 15 and the actuator by the numeral 81., Closing of the switch |36 will permit the second phase of'this circuit to energize the electro-magnet coil 40 so that its armature 45 will be moved to actuate the contact carrier 52 into contact closing position tof complete both phase circuits through the main switch. It will of course be understood that actuators 281 and 81 have previously been operated to close the respective contacts 83 and 84 and 283 and 284. If for any reason excessive currents flow through the first phase circuit, heater 116 will provide a temperature that will cause the thermostatic detent 215 to flex to release trigger 214 which in turn will move the actuator 281 to shift movable contact 285 out of engagement with its associate contacts 283 and 284 and thus break the electromagnet coil circuit thereby causing opening of the main switch. On the other hand if the abnormal conditions arise'in the second phase circuit, the heating coil 16 will be affected to cause iiexureI of the thermostatic detent 15 whereby the trigger 14 will be released to move the actuator 81 to break engagement of contacts ,83 and .84. .fi-Under no circumstances willthe construction of the thermostatic switches in this instance permit these switches to be held or tied in such a position in which contacts 283 and 284 or 83 and 84 would be bridged while abnormal conditions exists in either phase circuit. Extra terminals 30D-30| are provided on the switch where diierent phase electrical circuits are to be controlled.

From the aforegoing it may be lseen that applicant has provided an automatic electric switch adapted to protect electrical circuits so that under abnormal circumstances this switch will disconnect the main circuit, the construction of the switch being such that it canot beheld or maintained in circuit-closing position in any manner while 'such abnormal condition exists. He has also provided a switch in which short circuiting by the building up of a metallic lm in the housing, caused by arcing, is substantially eliminated and humming due to air gaps between the armature and its associate pole pieces is also practically eliminated by the provision of relatively movable laminations in one of the elements which permits alignment of \the laminations betweenv loaded trigger also moved by the actuator; a detent adapted to engage the triggerwhen it is moved into a certainv position and to retain said trigger in said position; a plurality of instrumentalities for rendering said movable contact ineffective to engage the stationary contact while the trigger is free of the detent.

-2. In an automatic switch, a stationary tact; a movable contact; an actuator having yieldable means engaging the movable contact to eect movement thereof into engagement with the stationary contact; a spring loaded trigger also moved by the actuator; a detent adapted to engage the trigger when it is moved into a certain 'position and to retain said trigger in said position; and means interposed between the trigger and movable contact for rendering the said contact ineiective to engage the stationary contact while the trigger-is free of the detent.

3. In an automatic switch,=a stationary contact; a movable contact; an actuator; resilient means interposed between the actuator and movable contact and adapted to move the movable contact toward engagement with the stationary contact; a spring loaded trigger moved by the actuator; a detent adapted to engage the trigger when it is moved into a. certain position and to retain said trigger in said position; and means associated with the actuator, in-

' .teiposed between the trigger and the movable contactfor engaging said contact and preventing its engagement with the stationary contact while the trigger is free of the detent. Y

4, In an automatic switch, a stationary contact; a movable contact; a resilient member urging tlie movable `contact toward the stationary contact; an actuator adapted to move the movn able contact into engagement with the stationary COD.-

spring stronger than said resilient member biasing the trigger toward the movable contact; a detent adapted to engage the trigger when it is moved into a certain position and to retain said trigger in said position; and instrumentalities including a member interposed between the trigger and movable contact, said member being urged by said trigger to hold the movable contact out of engagement with the stationary contact While the trigger is free of the detent.

5. InY an automatic switch, a stationarycontact; a movable contact having a cam portion; an actuator adapted to move the movable contact into engagement with the stationary contact and having a camming surface engageable with the cam portion of the movable contact; a trigger adapted to be moved by the actuator; a spring resisting movement of the trigger by the actuator; a detent adapted to engage the trigger and retain it in a certain position; and a member interposed between the trigger and movable contact, said member being actuated by the spring pressed trigger to engage the movable contact and said member, cam and camming surface preventing engagement of the movable contact with the stationary contact While the actuator is manually depressed.

6. In an automatic switch, a stationary contact;e a movable contact; a manually operable actuator for moving said movable contact into i engagement with the stationary contact; a detent; a spring loaded trigger adapted to be moved by the actuator into locking engagement with the detent for preventing immediate return of the actuator'in'to normal position; a lost motion connection between the actuator and trigger permitting a partial return of the actuator toward normal position upon being released; means ,for preventing engagement of the movable contact with the stationary contact while the trigger is moved toward engagement withvthe detent; and means for preventing such engagement of the contacts while the manual force upon the actuator is maintained after the last mentioned means becomes ineiective.

7. In an -automatic switch, a stationary contact; a movable contact; ,a manually operable actuator for moving said movable contact into engagement with the stationary contact, said interposed between the trigger and movable contact, and urged by the trigger to hold the movable contact out of engagement with the stationary contact during a portion of the movement of the actuator; and cam means for preventing engagement of theymovable contact with the stationary contact during a portion of the `movement of the actuator.

8. In an automatic switch a pair of stationary contacts; a movable contact for bridging the stationary contacts and having a projecting cam portion; a manually operable actuator fr moving said movable contact into engagement with the stationary contacts; yieldable means con-- y tion connection between the actuator and trigger permitting a partial return of the actuator toward normal position upon being released; means for preventing engagement of the movable contact with both of the stationary contacts during a portion of the movement of the trigger toward the engagement thereof by the detent; and a cam on the actuator, adapted'to engage the cam portion of the movable contact and urge it away from one of the stationary contacts immediately before the trigger engages the detent and while the manual force is exerted upon the actuator after said trigger engages the detent.

9. In an automatic switch, a pair of stationary contacts; a movable contact for bridging the stationary contacts and having a projecting cam portion; a manually operable actuator for moving said movable contacts into engagement :with the stationary contacts; a detent; a spring loaded trigger adapted to be movedvby the actuator into locking engagement with the detent 'for preventing immediate return of the actuator into normal position; a lost motion connection between the actuator and trigger permitting a partial return of the actuator toward normal position upon being released; means for preventing engagement of the movable contact with both of the stationary contacts until the trigger is moved and actually engaged by the detent, said means including a flange on the actuator, said flange having a sloping surface adapted to engage camportion oi the movable contact and move it away from one of the stationary contacts immediately prior to the engagement of the trigger with the detent, said flange maintaining the movable contact out of engagement with the stationary contacts until the actuator is released and permitted to move said partial distance toward normal position.

10. In an automatic switch, a stationary contact; a movable contact adapted to engage the stationary contact; an actuator for manually effecting engagement of the contacts; a member biased against a portion of the actuator in such a direction that movement of the actuator toward effecting engagement of the contacts is resisted; means supported by the actuator and substantially freely movable with respect to the actuator, said means engaging the movable contact and said member to bias the movable contact away from the stationary contact for a portion of the movement of the actuator toward effecting engagement of the contacts.

11. An electric switch comprising, in combination, a housing of insulating material providing compartments having walls; a thermostatically controlled switch in one compartment; a switch in the other compartment comprising stationary contacts secured to opposing walls of the compartment and a cooperating movable switch element for electrically connecting the stationary contacts; the walls intermediate the stationary contacts having recesses therein interrupting the substantially smooth surface between the stationary contacts to prevent the formation of a short circuting film on said walls.

12. An electric switch comprising, in combination, a housing of insulating material providing compartments having walls; a thermostatically controlled switch in one compartment; a switch in the other compartment comprising spaced stationary contacts secured to the housing and a cooperating movable switch element for electrically connecting the stationary contacts; the wallsr intermediate the stationary contacts having grooves therein to prevent the formation of a short circuiting lm on the walls.

CALVIN'J. WERNER.

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