US3906179A - Electrical switch and combination electrical resistor and switch - Google Patents

Electrical switch and combination electrical resistor and switch Download PDF

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US3906179A
US3906179A US364506A US36450673A US3906179A US 3906179 A US3906179 A US 3906179A US 364506 A US364506 A US 364506A US 36450673 A US36450673 A US 36450673A US 3906179 A US3906179 A US 3906179A
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Prior art keywords
movable contact
cam
contact
stationary contact
switch
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US364506A
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Jack A English
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CTS Corp
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CTS Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C10/00—Adjustable resistors
    • H01C10/30—Adjustable resistors the contact sliding along resistive element
    • H01C10/32—Adjustable resistors the contact sliding along resistive element the contact moving in an arcuate path
    • H01C10/36—Adjustable resistors the contact sliding along resistive element the contact moving in an arcuate path structurally combined with switching arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/12—Contacts characterised by the manner in which co-operating contacts engage
    • H01H1/14—Contacts characterised by the manner in which co-operating contacts engage by abutting
    • H01H1/18—Contacts characterised by the manner in which co-operating contacts engage by abutting with subsequent sliding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H19/00—Switches operated by an operating part which is rotatable about a longitudinal axis thereof and which is acted upon directly by a solid body external to the switch, e.g. by a hand
    • H01H19/54—Switches operated by an operating part which is rotatable about a longitudinal axis thereof and which is acted upon directly by a solid body external to the switch, e.g. by a hand the operating part having at least five or an unspecified number of operative positions
    • H01H19/60—Angularly-movable actuating part carrying no contacts
    • H01H19/62—Contacts actuated by radial cams
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H21/00—Switches operated by an operating part in the form of a pivotable member acted upon directly by a solid body, e.g. by a hand
    • H01H21/02—Details
    • H01H21/18—Movable parts; Contacts mounted thereon
    • H01H21/36—Driving mechanisms
    • H01H21/40—Driving mechanisms having snap action
    • H01H21/44—Driving mechanisms having snap action produced by flexing blade springs

Definitions

  • ABSTRACT A switch comprising a stationary contact, a movable contact cooperating therewith and a resilient member carrying the movable contact.
  • a movable cam engages the resilient member and controls the movement thereof into and out of operative engagement with the stationary contact.
  • the cam is located at a position on a rotary actuating means widely spaced from the axis of rotation thereof, whereby only a small rotary movement of the actuating means is required for the operative movements of the cam.
  • This preferred arrangement preferably includes means whereby in the opening movement of this switch the movable contact is caused by the operation of the cam to make a wiping movement along the surface of the stationary contact, prior to the actual separation of the contacts, with the initial engagement between the movable contact and the stationary contact during the closing movement of the switch taking place at a point on the stationary contact surface spaced from that point of the stationary contact surface of which the final separation of the movable contact from the stationary contact takes place during the opening movement of the switch.
  • Terminals connect the switch to an electric circuit with the movable contact being integrally connected through the resilient member to one of the terminals. When the switch is in an open position, the cam physically separates the movable contact from the stationary contact.
  • This invention relates to an electrical switch and more especially to a snap-action switch, and also to a combination of such a switch with a variable resistance.
  • the cam follower and the movable contactor are interconnected by a resilient member, the relative movement between the cam and the cam follower causing energy to be stored in or released from such resilient member.
  • the specification describes various alternative forms of spring or combination of springs to constitute the complete movable contact device incorporating the cam follower, the resilient member and the contactor.
  • Another prior art switch has utilized a contact spring having one end pivoting within a V-shaped notch in a contact member electrically connected to a terminal and the other end functioning as a movable contact having snap action movement between open and closed switch positions.
  • a problem associated with this construction resides in the possiblity of the one end of the contact spring moving out of the V-shaped notch thereby resulting in inadvertent displacement of the contact spring with attached movable contact and possible failure of the switch.
  • Another problem with this construction is that since the contact spring pivots on the contact member the resistance at this point is increased producing high temperatures and the possibility of burnout resulting in failure of the switch. Accordingly it would be desirable to fabricate a snap action switch eliminating the possibility of inadvertent displacement of the movable contact and burnout of the contact spring end pivoting in the notch.
  • the primary object of the present invention is therefore to provide an improved construction of switch, which will retain the best characteristics of the abovedescribed switches but will enable some of the troubles arising with such switches to be avoided.
  • a more specific object of the invention is to provide for wiping engagement between the cooperating contacts.
  • a further object of the invention is to provide for some degree of self cleaning of the contacts during operation thereof.
  • Yet another object of the invention is to provide additional preloading of the spring prior to the break of the contacts. More generally, a further object of the invention is to provide a simpler construction of switch with fewer separate parts, thereby giving greater consistency and reliability in operation.
  • An additional object of the invention is to provide a snap action switch having an integral movable contact and terminal thereby eliminating the possibility of inadvertent displacement of the movable contact and burnout of a contact spring pivoting on a contact member. Still further objects of the invention will become apparent from the particular description of the switch hereinafter given and from the appended claims.
  • an electric switch comprises a stationary contact, a movable contact cooperating therewith, a resilient member carrying the movable contact, a movable cam engaging with and controlling the movements of the resilient member for moving the movable contactor into and out of operative engagement with the stationary contact, actuating means for effecting the movements of the cam, and means whereby in the opening movement of the switch the movable contact is caused by the operation of the cam to make a wiping movement along the surface of the stationary contact prior to the actual separation of the contacts.
  • the resilient member incorporates a cam follower with which the cam cooperates, such cam follower being shaped to cause the movable contact to pass through a neutral position whereby the movable contact operates with a snapaction in its closing and opening movements.
  • the arrangement may conveniently include means whereby in the approach to the said neutral position the cam imparts additional loading to the resilient member, such additional loading when released after the passing of the neutral position producing the increased speed of the snap-action in the operative movements of the switch.
  • the electric switch comprises a stationary contact, a movable contact cooperating therewith, a resilient member carrying the movable contact a movable cam engaging with and controlling the movements of the resilient member for moving the movable contact into and out of operative engagement with the stationary contact, actuating means for effecting the movements of the cam, and means whereby the initial engagement between the movable contact and the stationary contact during the closing movement of the switch and the final separation of the movable contact from the stationary contact during the opening movement of the switch take place at different points spaced apart on the surface of the stationary contact.
  • the switch preferably includes means whereby, for effecting closing of the switch, part of the cam is caused to move over a convex portion of the resilient member and thereby to force such convex portion in a direction to impart additional loading to the resilient member, such movement continuing until the said convex portion escapes past the operative part of the cam and thereby moves the movable contact at high speed into engagement with a point of the stationary contact surface, and means whereby for effecting opening of the switch the operative part of the cam is caused to effect a return movement over the said convex portion of the resilient member again forcing it in a direction to impart additional loading to the resilient member, whereby the movable contact is caused to make a wiping movement along the surface of the stationary contact member from the said point of engagement, such wiping movement continuing until the resilient member escapes past the operative part of the cam and thereby causes the movable contact to separate at high speed from a different point of the stationary contact surface and to move into the open position.
  • an electric switch comprises a stationary contact, a movable contact cooperating therewith, a resilient member carrying the movable contact, a movable cam engaging with and controlling the movement of the resilient member for moving the movable contact into and out of operative engagement with the stationary contact, actuating means for effecting the movements of the cam, terminals for connection to an electric circuit to be controlled by the switch, whereby the movable contact is integrally connected With one of such terminals and the stationary contact is integrally connected with another of such terminals.
  • an electric switch comprises a stationary contact, a movable contact cooperating therewith, a resilient member acting to urge the movable contact towards a position in which it makes operative engagement with the stationary contact, a movable cam engaging with and controlling the movements of the resilient member for moving the movable contact into and out of operative engagement with the stationary contact, and means whereby for the opening of the switch the cam is caused to move into a position in which it is interposed between the movable contact and the stationary contact and thereby serves to hold the movable contact out of engagement with the stationary contact until a subsequent closing operation of the switch is initiated, the switch preferably including means whereby the cam in its movement towards the said interposition between the cooperating contacts first flexes the resilient member thereby imparting additional loading thereto and also causing the movable contact to make a wiping movement along the surface of the stationary contact, such wiping movement continuing until the resilient member escapes past the operative part of the cam and thereby causes the movable contact to separate at
  • the switch comprises a stationary contact, a movable contact cooperating therewith, a resilient member carrying the movable contact, a movable cam engaging with and controlling the movement of the resilient member for moving the movable contact into and out of operative engagement with the stationary contact, rotary actuating means for effecting the movement of the cam, the cam being located at a position on the actuating means widely spaced from the axis of rotation thereof, whereby only a relatively small rotary movement of the actuating means is required for the operative movements of the cam.
  • This preferred arrangement preferably includes means whereby in the opening movement of the switch the movable contact is caused by the operation of the cam to make a wiping movement along the surface of the stationary contact prior to the actual separation of the contacts, the initial engagement between the movable contact and the stationary contact during the closing movement of the switch taking place at a point of the stationary contact surface spaced from that point of the stationary contact surface at which the final separation of the movable contact from the stationary contact takes place during the opening movement of the switch.
  • the electric switch according to the invention is especially suitable for use in combination with a variable resistance, and in such arrangement any of the foregoing switch arrangements can be used in combination with a resistance element, a movable contactor making wiping engagement with such element for varying the effective resistance value thereof, and an actuator for driving such contact along the resistance element, such actuator also being use for effecting the movements of the movable cam of the electric switch.
  • FIG. 1 is an isometric view of an electrical control built in accord with the present invention
  • FIG. 2 is an axial sectional view of the unit
  • FIG. 3 is an end view of the variable resistance of the unit, the electric switch and the actuator being removed;
  • FIG. 4 is a front view of the actuator disc showing mounted thereon the movable contactor cooperating with the resistance element;
  • FIG. 5 is a front view of the electric switch, with the resistance and the contactor removed, the switch being shown in the closed position;
  • FIG. 6 is a view similar to that of FIG. 5 showing the switch in the open position
  • FIG. 7 shows the resilient member in its normal unstressed condition
  • FIG. 8 illustrates the positions of the parts at an intermediate stage in the closing movement of the switch
  • FIG. 9 illustrates the positions of the parts at an intermediate stage in the opening movement of the switch.
  • FIG. is a diagram illustrating the various paths of movement of the movable contact.
  • an insulating disc 11 bears on one face an arcuate resistance element 12, the two ends of which are connected respectively to two terminals 13 protruding from the edge of the disc at one side, together with a collector ring 14 mounted coaxially with the arcuate resistance element 12 and connected to a third terminal 15 protruding from the disc centrally between the two terminals 13.
  • These three terminals are the operative terminals of the variable resistance device, and will be referred to hereinafter as the resistance terminals to distinguish them from the switch terminals referred to below.
  • a rotatable actuating shaft 18 Passing through a central hole in the disc 11 is a rotatable actuating shaft 18, carrying a second disc 19, to one face of which is secured a shaped contact member carrying a pair of spring contact fingers 21, whose ends extend side by side and press resiliently against the resistance element 12 on the first disc 1 1, and a second pair of spring contact fingers 22, whose ends overlap one another and press resiliently against the collector ring 14, the contact member 20 with its two pairs of contact fingers thus constituting in use a bridging connection between the collector ring 14 and a variable point on the arcuate resistance element 12.
  • a bearing member 23 is provided having a short cylindrical extension passing through the central hole in the disc 11 with its end 24 splayed outwardly to grip the inner edge of the disc.
  • This bearing member 23 carries a screw-thread 25 for mounting the switch on a mounting panel (not shown) the main body portion of the bearing member having the external shape of a nut to facilitate such mounting.
  • a thin metal plate 26 is interposed between the bearing member 23 and the insulating disc 11, such plate being slit to permit its side portions 27 to be bentup slightly close to faces of the bearing member, after assembly, thereby preventing any relative rotation between the bearing member and the insulating disc.
  • the actuating shaft 18 has a short extension 28 beyond the contact-carrying disc 19 making bearing engagement with a fitting 29 projecting from an insulating base-plate 30, to which is secured a metal cover 31.
  • This cover 31 is firmly attached to the insulating disc 11, by means of tags 32 which are bent over the edge of the disc to engage with the side portions 27 on the metal plate 26 secured to the disc 11.
  • a small portion 33 of the cover is bent inwardly to form a stop cooperating with a projection 34 from the periphery of the contact-carrying disc 19 on the shaft 18, thus limiting the possible movement of the shaft to less than one complete rotation.
  • An opening 35 is cut away on one side of the cover 31 to accommodate the connections from the collector ring 14 and from the resistance 12 to the resistance terminals 13, 15. It will usually be convenient for the ends of the terminals to be bent over slightly to extend generally in the direction of the axis of the shaft 18 outside the cover 31.
  • the disc 19 also carries a projecting cam 37, the operation of which will be described
  • the insulating base-plate is circular in shape, with the omission ofa small segment 38 (see FIG. 1), so that it has a flat wall on the side nearest to the projecting resistance terminals l3, l5 and is provided on its inner face with a shaped recess 39 around the fitting 29.
  • walls of the recess 39 are shaped (see FIG. 6) to provide bearing surfaces for two cooperating contact members 40, 44.
  • the contact member 40 is of generally rigid construction and carries at one end the stationary switch contact 41.
  • the main portion of this member 40 is held firmly bedded against one wall 42 of the recess 39 by a part passing through a narrow slit in the base 30 integrally connected to a projecting switch terminal 43.
  • Such main portion lies mainly within the recess 39, but the end-piece carrying the stationary switch contact 41 is made somewhat larger, so that the stationary switch contact itself projects out of the recess 39.
  • the other contact member 44 is in the form of a resilient metal strip bent, in its normal unstressed condition, into the shape shown in FIG. 7. In its operative positions, as shown in FIGS. 5 and 6, this member is prestressed by forcing it into a shape fitting into the recess 39.
  • Such stressed shape having the form mainly consisting of three sides 45, 46, 47 of a rectangle extending from one side firmly bedded against the wall 48 of the recess 39 opposite that against which the main portion of the first contact member 40 is bedded, the third side 47 being spaced from and approximately parallel to the main portion of the first contact member 40, such third side having a curved end portion 49 leading through a sharply convex corner piece 50 to a turnedback straight end-piece 51 normally bedded against an oblique wall 52 of the recess 39.
  • the side 45 of the contact member 44 has a part passing through a narrow slit in the base 30 integrally connected to the second switch terminal 53.
  • the movable contact 54 of the switch is carried by the third side 47 of the contact member 44 on the curved portion 49 thereof, and it is to be noted that such movable contact 54 is integrally connected through the resilient metal strip 44 to the second switch terminal 53.
  • the curved portion 49 carrying the movable contact 54, the corner piece 50 and the end-piece 51 project out of the recess, so as to lie in the path of movement of the cam 55 on the disc 19, while the remainder of the contact member 44 lies mainly within the recess, the cam being so positioned that it can move past the narrower parts of the contact member 44 without engagement therewith.
  • Such cam 55 is of generally triangular shape with rounded comers, and its operative portion consists of the corner 56 and part of the inner face 57 thereof.
  • FIGS. 5 and 6 respectively showing the closed and open positions of the switch.
  • the open position of the switch is determined by the engagement of the projection 34 on the actuator disc 19 with the fixed stop 33 at the end of the opening movement of the actuator, which takes place in a counter-clockwise direction relatively to the stationary contact 41, as viewed in FIGS. 5 and 6.
  • the cam 55 (which as above mentioned is made of insulating material) lies in part, between the stationary and movable contact 41 and 54 and physically holds these contacts apart against the downward component of the spring force.
  • the end-piece 51 of the resilient member 44 is held by the actuator resilience of such member in engagement with the oblique wall 52 of the recess 39, part of the curved portion 49 of the resilient member lying in engagement with the inner face 57 of the cam.
  • the actuator shaft 18 is operated to rotate the disc 19 carrying the cam 55 in the clockwise direction (in FIG. 6).
  • This causes the inner face 57 of the cam to ride over the convex portion 50 of the third arm of the resilient member, and thereby to force the endpiece 51 to make a short upward sliding movement along the oblique wall 52 of the recess and thereafter to separate from such oblique wall (to the position shown in FIG. 8) in a direction to distort the resilient member still further from its normal unstressed shape, thereby imparting additional loading to such member.
  • the actuator shaft 18 is operated to rotate the disc 19 in the counter-clockwise direction (as viewed in FIGS. and 6).
  • This causes the corner 56 of the cam 55 to engage with a point on the straight end-piece 51 of the movable contact member 44 near the convex comer-piece 50, and to force such end-piece 51 out of engagement with the oblique wall 52 of the recess 39 in a direction to apply additional loading to the resilient member 44.
  • the movable contact 54 makes a sliding movement along the surface of the stationary contact 41. The parts are now in the positions shown in FIG. 3.
  • the various paths of movement of the movable contact 54 are indicated in the diagram of FIG. 10.
  • In the open position of the switch such contact is in the position indicated at 58 in FIG. 10.
  • During the closing movement such contact first moves from 58 and 59 and thereafter from 59 to engage with the stationary contact at the point 60. This is the closed position of the switch.
  • the movable contact 54 first slides along the surface of the stationary contact 41 from the point 60 to the point 61, and then separates from the stationary contact and moves back to the point 58 in the open position of the switch..
  • the various paths of movement of the movable contact thus together form a pattern somewhat resembling a butterfly shape.
  • the chief advantage of this complex movement is that the point of engagement 60 of the movable contact with the stationary contact during the closing movement of the switch is spaced apart from the point 61 of the stationary contact at which the movable contact separates from the stationary contact during the opening movement.
  • This is advantageous for two reasons, first that the arcing which takes place just before the contacts engage during the closing movment will occur at a point on the stationary contact spaced apart from that at which arcing occurs on separation of the contacts during the opening movement, so that the harmful effects on the contact surface of pitting due to arcing are not concentrated at one point, as they normally are in switches in which the opening movement takes place along exactly the same path as the closing movement but in the opposite direction.
  • the second advantage of the arrangement is that the sliding movement of the contacts in the early stage of the opening movement has the effect of wiping away the products of arcing, so that the contacts have a self-cleaning affect. While there is a relatively wide spacing between the arcing points on the stationary contact 41, the slight curvature of the portion 49 of the movable contact also causes a smaller spacing apart of the arcing points on the movable contact, so that the advantageous effects apply to both of the cooperating contacts, whereby the useful life of both contacts, before replacement is needed, is greatly increased.
  • An electric switch comprising a housing, a stationary contact supported in the housing, a resilient member having a movable contact and a terminal integral therewith supported in the housing, both the movable contact and the terminal being made from the same material and having the same thickness, said movable contact being preformed to effect a bias against said stationary contact, a camming surface integral with the housing and adjacent to the movable contact, a movable cam mounted for movement in an interference path with said'resilient member for moving the movable contact into and out of operative engagement with the stationary contact, the camming surface controlling movement of the movable contact toward and away from the stationary contact and biasing the movable contact toward the stationary contact when the cam is spaced from the movable contact, said movable contact being mounted for movement both along said stationary contact and away from said stationary contact, and actuating means for effecting movements of the cam whereby upon moving the cam in one direction the cam engages the movable contact increasing the force between the movable contact and the stationary contact until the movable contact is
  • said resilient member comprises a metal strip having a portion fixedly secured on an insulating disk and forming said terminal.
  • An electric switch comprising an insulating baseplate, a stationary contact and a resilient member supported on said base-plate, said resilient member having a movable contact and a terminal integral therewith, both the movable contact and the terminal being made from the same material and having the same thickness, said movable contact being preformed to effect a bias against said stationary contact, a caming surface disposed on the base-plate adjacent to the movable contact and integral therewith, a movable cam mounted for rotation in an interference path with said resilient member for moving the movable contact into and out of the operative engagement with the stationary contact, the caming surface controlling movement of the movable contact toward and away from the stationary contact and biasing the movable contact toward the stationary contact when the cam is spaced from the movable contact, and actuating means for effecting movements of the cam, said cam being located at a position widely spaced from its axis of rotation whereby only relatively small movements movments are required of the actuating means for effecting the operative movements of the cam whereby upon moving the cam
  • said resilient member comprises a metal strip having the shape of a three sided rectangle, one of the sides being fixedly secured to said base-plate and having a portion extending through said base-plate forming a terminal.
  • An electric switch comprising an insulating baseplate containing a shaped recess, a stationary contact supported in said recess in said base-plate and having a terminal integral therewith, and a resilient member supported in said recess in said base-plate, said resilient member comprising a C-shaped metal strip having a movable contact and a terminal integral therewith, said resilient member and said stationary contact containing portions extending out of said recess, said movable contact and integral terminal being made from the same material and having the same thickness and being preformed to efl'ect a bias against said stationary contact, a camming surface forming a wall of said recess and disposed adjacent to the movable contact and integral therewith, a movable cam mounted for rotation in an interference path with said resilient member for moving the movable contact into and out of the operative engagement with the stationary contact, said cam physically separating the movable contact from the stationary contact when the switch is in the off position, the camming surface controlling movement of the movable contact toward and
  • An electric switch comprising an insulating baseplate containing a shaped recess, a stationary contact supported in said recess in said base-plate, and a resilient member supported in said recess in said base-plate, said resilient member having a movable contact and a terminal integral therewith, said resilient member and said stationary contact containing portions extending out of said recess and both the movable contact and the terminal being made from the same material and having the same thickness, said movable contact being preformed to effect a bias against said stationary contact, a camming surface forming a wall of said recess and disposed adjacent to the movable contact and integral therewith, a movable cam mounted for rotation in an interference path with said resilient member for moving the movable contact into and out of the operative engagement with the stationary contact, the camming surface controlling movement of the movable contact toward and away from the stationary contact and biasing the movable contact toward the stationary contact when the cam is spaced from the movable contact, and actuating means for effecting movements of the

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Abstract

A switch comprising a stationary contact, a movable contact cooperating therewith and a resilient member carrying the movable contact. A movable cam engages the resilient member and controls the movement thereof into and out of operative engagement with the stationary contact. The cam is located at a position on a rotary actuating means widely spaced from the axis of rotation thereof, whereby only a small rotary movement of the actuating means is required for the operative movements of the cam. This preferred arrangement preferably includes means whereby in the opening movement of this switch the movable contact is caused by the operation of the cam to make a wiping movement along the surface of the stationary contact, prior to the actual separation of the contacts, with the initial engagement between the movable contact and the stationary contact during the closing movement of the switch taking place at a point on the stationary contact surface spaced from that point of the stationary contact surface of which the final separation of the movable contact from the stationary contact takes place during the opening movement of the switch. Terminals connect the switch to an electric circuit with the movable contact being integrally connected through the resilient member to one of the terminals. When the switch is in an open position, the cam physically separates the movable contact from the stationary contact.

Description

United States Patent [191 English [4 1 Sept. 16, 1975 ELECTRICAL SWITCH AND COMBINATION ELECTRICAL RESISTOR AND SWITCH [75] Inventor: Jack A. English, Elkhart, Ind.
[73] Assignee: CTS Corporation, Elkhart, Ind.
[22] Filed: May 29, 1973 [21] Appl. No.: 364,506
Related US. Application Data [63] Continuation of Ser. No. 95,518, Dec. 7, 1970,
Primary Examiner-David Smith, Jr.
[57] ABSTRACT A switch comprising a stationary contact, a movable contact cooperating therewith and a resilient member carrying the movable contact. A movable cam engages the resilient member and controls the movement thereof into and out of operative engagement with the stationary contact. The cam is located at a position on a rotary actuating means widely spaced from the axis of rotation thereof, whereby only a small rotary movement of the actuating means is required for the operative movements of the cam. This preferred arrangement preferably includes means whereby in the opening movement of this switch the movable contact is caused by the operation of the cam to make a wiping movement along the surface of the stationary contact, prior to the actual separation of the contacts, with the initial engagement between the movable contact and the stationary contact during the closing movement of the switch taking place at a point on the stationary contact surface spaced from that point of the stationary contact surface of which the final separation of the movable contact from the stationary contact takes place during the opening movement of the switch. Terminals connect the switch to an electric circuit with the movable contact being integrally connected through the resilient member to one of the terminals. When the switch is in an open position, the cam physically separates the movable contact from the stationary contact.
12 Claims, 10 Drawing Figures ELECTRICAL SWITCH AND COMBINATION ELECTRICAL RESISTOR AND SWITCH This is a continuation of application Ser. No. 95,518 filed Dec. 7, 1970 now abandoned.
This invention relates to an electrical switch and more especially to a snap-action switch, and also to a combination of such a switch with a variable resistance.
The specification of U.S. Pat. No. 3,370,261 filed on the Jan. 4, 1965 in the name of J. D. VanBenthuysen, assigned to the same assignee or the present application, describes a snap-action switch comprising a stationary contact, a movable contactor cooperating therewith, a conductive guide member which is connected to a terminal of the switch and serves to guide the movement of such contactor into and out of engagement with the stationary contact, a cam follower connected to the movable contactor, and a cam movable in either of two opposite directions for urging the cam follower through an unstable neutral position and thereby causing the contactor to move into or out of engagement with the stationary contact, the direction of movement of the cam being opposite to the direction of movement of the contactor. The cam follower and the movable contactor are interconnected by a resilient member, the relative movement between the cam and the cam follower causing energy to be stored in or released from such resilient member. The specification describes various alternative forms of spring or combination of springs to constitute the complete movable contact device incorporating the cam follower, the resilient member and the contactor.
When such switch is used in combination with a variable resistance operable by means of a rotatable control shaft, the actuating cam of the switch is driven by the control shaft of the variable resistance.
Such switch and its combination with a variable resistance have in general operated well in practice, but various characteristics thereof have proved troublesome. One drawback has been that the make and the break of the switch have taken place at the same points of the cooperating contacts, so that products of arcing and the erosion of the contact surfaces are all directed at the same points, thereby shortening the useful life of the switch and presenting problems for the cleaning of the contacts, the closing and opening move ments taking place along the same path, approximately at the right angles to the surfaces of the cooperating contacts, without any self cleaning effect which could come from the use of a wiping engagement between the contacts. Another difficulty is that the complete moving contact device is of complicated construction with the result that it becomes extremely difficult to ensure that one such device will have the same spring characteristics as another. Further, the complete switch is made up of a considerable number of separate parts, and this makes it difficult to reduce manufacturing costs and to ensure consistency and reliability of the switch.
Another prior art switch has utilized a contact spring having one end pivoting within a V-shaped notch in a contact member electrically connected to a terminal and the other end functioning as a movable contact having snap action movement between open and closed switch positions. A problem associated with this construction resides in the possiblity of the one end of the contact spring moving out of the V-shaped notch thereby resulting in inadvertent displacement of the contact spring with attached movable contact and possible failure of the switch. Another problem with this construction is that since the contact spring pivots on the contact member the resistance at this point is increased producing high temperatures and the possibility of burnout resulting in failure of the switch. Accordingly it would be desirable to fabricate a snap action switch eliminating the possibility of inadvertent displacement of the movable contact and burnout of the contact spring end pivoting in the notch.
The primary object of the present invention is therefore to provide an improved construction of switch, which will retain the best characteristics of the abovedescribed switches but will enable some of the troubles arising with such switches to be avoided. A more specific object of the invention is to provide for wiping engagement between the cooperating contacts. A further object of the invention is to provide for some degree of self cleaning of the contacts during operation thereof. Yet another object of the invention is to provide additional preloading of the spring prior to the break of the contacts. More generally, a further object of the invention is to provide a simpler construction of switch with fewer separate parts, thereby giving greater consistency and reliability in operation. An additional object of the invention is to provide a snap action switch having an integral movable contact and terminal thereby eliminating the possibility of inadvertent displacement of the movable contact and burnout of a contact spring pivoting on a contact member. Still further objects of the invention will become apparent from the particular description of the switch hereinafter given and from the appended claims.
According to one aspect of the-present invention, an electric switch comprises a stationary contact, a movable contact cooperating therewith, a resilient member carrying the movable contact, a movable cam engaging with and controlling the movements of the resilient member for moving the movable contactor into and out of operative engagement with the stationary contact, actuating means for effecting the movements of the cam, and means whereby in the opening movement of the switch the movable contact is caused by the operation of the cam to make a wiping movement along the surface of the stationary contact prior to the actual separation of the contacts. Preferably, the resilient member incorporates a cam follower with which the cam cooperates, such cam follower being shaped to cause the movable contact to pass through a neutral position whereby the movable contact operates with a snapaction in its closing and opening movements. The arrangement may conveniently include means whereby in the approach to the said neutral position the cam imparts additional loading to the resilient member, such additional loading when released after the passing of the neutral position producing the increased speed of the snap-action in the operative movements of the switch.
The electric switch according to another aspect of the present invention, comprises a stationary contact, a movable contact cooperating therewith, a resilient member carrying the movable contact a movable cam engaging with and controlling the movements of the resilient member for moving the movable contact into and out of operative engagement with the stationary contact, actuating means for effecting the movements of the cam, and means whereby the initial engagement between the movable contact and the stationary contact during the closing movement of the switch and the final separation of the movable contact from the stationary contact during the opening movement of the switch take place at different points spaced apart on the surface of the stationary contact. With this arrangement, the switch preferably includes means whereby, for effecting closing of the switch, part of the cam is caused to move over a convex portion of the resilient member and thereby to force such convex portion in a direction to impart additional loading to the resilient member, such movement continuing until the said convex portion escapes past the operative part of the cam and thereby moves the movable contact at high speed into engagement with a point of the stationary contact surface, and means whereby for effecting opening of the switch the operative part of the cam is caused to effect a return movement over the said convex portion of the resilient member again forcing it in a direction to impart additional loading to the resilient member, whereby the movable contact is caused to make a wiping movement along the surface of the stationary contact member from the said point of engagement, such wiping movement continuing until the resilient member escapes past the operative part of the cam and thereby causes the movable contact to separate at high speed from a different point of the stationary contact surface and to move into the open position.
According to yet another aspect of the present invention, an electric switch comprises a stationary contact, a movable contact cooperating therewith, a resilient member carrying the movable contact, a movable cam engaging with and controlling the movement of the resilient member for moving the movable contact into and out of operative engagement with the stationary contact, actuating means for effecting the movements of the cam, terminals for connection to an electric circuit to be controlled by the switch, whereby the movable contact is integrally connected With one of such terminals and the stationary contact is integrally connected with another of such terminals.
According to a still further aspect of the present invention, an electric switch comprises a stationary contact, a movable contact cooperating therewith, a resilient member acting to urge the movable contact towards a position in which it makes operative engagement with the stationary contact, a movable cam engaging with and controlling the movements of the resilient member for moving the movable contact into and out of operative engagement with the stationary contact, and means whereby for the opening of the switch the cam is caused to move into a position in which it is interposed between the movable contact and the stationary contact and thereby serves to hold the movable contact out of engagement with the stationary contact until a subsequent closing operation of the switch is initiated, the switch preferably including means whereby the cam in its movement towards the said interposition between the cooperating contacts first flexes the resilient member thereby imparting additional loading thereto and also causing the movable contact to make a wiping movement along the surface of the stationary contact, such wiping movement continuing until the resilient member escapes past the operative part of the cam and thereby causes the movable contact to separate at high speed from the surface of the stationary contact.
With all the arrangements above described, it is especially convenient (although the invention is not limited thereto) for the operative movements of the cam to be executed in a rotary path about an axis, and in a preferred arrangement, the switch comprises a stationary contact, a movable contact cooperating therewith, a resilient member carrying the movable contact, a movable cam engaging with and controlling the movement of the resilient member for moving the movable contact into and out of operative engagement with the stationary contact, rotary actuating means for effecting the movement of the cam, the cam being located at a position on the actuating means widely spaced from the axis of rotation thereof, whereby only a relatively small rotary movement of the actuating means is required for the operative movements of the cam. This preferred arrangement preferably includes means whereby in the opening movement of the switch the movable contact is caused by the operation of the cam to make a wiping movement along the surface of the stationary contact prior to the actual separation of the contacts, the initial engagement between the movable contact and the stationary contact during the closing movement of the switch taking place at a point of the stationary contact surface spaced from that point of the stationary contact surface at which the final separation of the movable contact from the stationary contact takes place during the opening movement of the switch.
The electric switch according to the invention is especially suitable for use in combination with a variable resistance, and in such arrangement any of the foregoing switch arrangements can be used in combination with a resistance element, a movable contactor making wiping engagement with such element for varying the effective resistance value thereof, and an actuator for driving such contact along the resistance element, such actuator also being use for effecting the movements of the movable cam of the electric switch.
The invention may be carried into practice in various ways, but a preferred practical construction of a unit incorporating an electric switch and a variable resistance, according thereto is illustrated by way of example in the accompanying drawings wherein the same reference numerals have been applied to like parts and wherein:
FIG. 1 is an isometric view of an electrical control built in accord with the present invention;
FIG. 2 is an axial sectional view of the unit;
FIG. 3 is an end view of the variable resistance of the unit, the electric switch and the actuator being removed;
FIG. 4 is a front view of the actuator disc showing mounted thereon the movable contactor cooperating with the resistance element;
FIG. 5 is a front view of the electric switch, with the resistance and the contactor removed, the switch being shown in the closed position;
FIG. 6 is a view similar to that of FIG. 5 showing the switch in the open position;
FIG. 7 shows the resilient member in its normal unstressed condition;
FIG. 8 illustrates the positions of the parts at an intermediate stage in the closing movement of the switch;
FIG. 9 illustrates the positions of the parts at an intermediate stage in the opening movement of the switch; and
FIG. is a diagram illustrating the various paths of movement of the movable contact.
In this construction, an insulating disc 11 bears on one face an arcuate resistance element 12, the two ends of which are connected respectively to two terminals 13 protruding from the edge of the disc at one side, together with a collector ring 14 mounted coaxially with the arcuate resistance element 12 and connected to a third terminal 15 protruding from the disc centrally between the two terminals 13. These three terminals are the operative terminals of the variable resistance device, and will be referred to hereinafter as the resistance terminals to distinguish them from the switch terminals referred to below. Passing through a central hole in the disc 11 is a rotatable actuating shaft 18, carrying a second disc 19, to one face of which is secured a shaped contact member carrying a pair of spring contact fingers 21, whose ends extend side by side and press resiliently against the resistance element 12 on the first disc 1 1, and a second pair of spring contact fingers 22, whose ends overlap one another and press resiliently against the collector ring 14, the contact member 20 with its two pairs of contact fingers thus constituting in use a bridging connection between the collector ring 14 and a variable point on the arcuate resistance element 12. To locate the axis of the actuating shaft 18 in proper alignment relatively to the insulating disc 1 1 a bearing member 23 is provided having a short cylindrical extension passing through the central hole in the disc 11 with its end 24 splayed outwardly to grip the inner edge of the disc. This bearing member 23 carries a screw-thread 25 for mounting the switch on a mounting panel (not shown) the main body portion of the bearing member having the external shape of a nut to facilitate such mounting. A thin metal plate 26 is interposed between the bearing member 23 and the insulating disc 11, such plate being slit to permit its side portions 27 to be bentup slightly close to faces of the bearing member, after assembly, thereby preventing any relative rotation between the bearing member and the insulating disc.
The actuating shaft 18 has a short extension 28 beyond the contact-carrying disc 19 making bearing engagement with a fitting 29 projecting from an insulating base-plate 30, to which is secured a metal cover 31. This cover 31 is firmly attached to the insulating disc 11, by means of tags 32 which are bent over the edge of the disc to engage with the side portions 27 on the metal plate 26 secured to the disc 11. A small portion 33 of the cover is bent inwardly to form a stop cooperating with a projection 34 from the periphery of the contact-carrying disc 19 on the shaft 18, thus limiting the possible movement of the shaft to less than one complete rotation. An opening 35 is cut away on one side of the cover 31 to accommodate the connections from the collector ring 14 and from the resistance 12 to the resistance terminals 13, 15. It will usually be convenient for the ends of the terminals to be bent over slightly to extend generally in the direction of the axis of the shaft 18 outside the cover 31. The disc 19 also carries a projecting cam 37, the operation of which will be described later herein.
The insulating base-plate is circular in shape, with the omission ofa small segment 38 (see FIG. 1), so that it has a flat wall on the side nearest to the projecting resistance terminals l3, l5 and is provided on its inner face with a shaped recess 39 around the fitting 29. The
walls of the recess 39 are shaped (see FIG. 6) to provide bearing surfaces for two cooperating contact members 40, 44.
The contact member 40 is of generally rigid construction and carries at one end the stationary switch contact 41. The main portion of this member 40 is held firmly bedded against one wall 42 of the recess 39 by a part passing through a narrow slit in the base 30 integrally connected to a projecting switch terminal 43. Such main portion lies mainly within the recess 39, but the end-piece carrying the stationary switch contact 41 is made somewhat larger, so that the stationary switch contact itself projects out of the recess 39.
The other contact member 44 is in the form of a resilient metal strip bent, in its normal unstressed condition, into the shape shown in FIG. 7. In its operative positions, as shown in FIGS. 5 and 6, this member is prestressed by forcing it into a shape fitting into the recess 39. Such stressed shape having the form mainly consisting of three sides 45, 46, 47 of a rectangle extending from one side firmly bedded against the wall 48 of the recess 39 opposite that against which the main portion of the first contact member 40 is bedded, the third side 47 being spaced from and approximately parallel to the main portion of the first contact member 40, such third side having a curved end portion 49 leading through a sharply convex corner piece 50 to a turnedback straight end-piece 51 normally bedded against an oblique wall 52 of the recess 39. The side 45 of the contact member 44 has a part passing through a narrow slit in the base 30 integrally connected to the second switch terminal 53. The movable contact 54 of the switch is carried by the third side 47 of the contact member 44 on the curved portion 49 thereof, and it is to be noted that such movable contact 54 is integrally connected through the resilient metal strip 44 to the second switch terminal 53. The curved portion 49 carrying the movable contact 54, the corner piece 50 and the end-piece 51 (like the stationary contact 41) project out of the recess, so as to lie in the path of movement of the cam 55 on the disc 19, while the remainder of the contact member 44 lies mainly within the recess, the cam being so positioned that it can move past the narrower parts of the contact member 44 without engagement therewith. Such cam 55 is of generally triangular shape with rounded comers, and its operative portion consists of the corner 56 and part of the inner face 57 thereof.
The operation of the switch will now be described, more especially with reference to FIGS. 5 and 6, respectively showing the closed and open positions of the switch.
The open position of the switch, shown in FIG. 6, is determined by the engagement of the projection 34 on the actuator disc 19 with the fixed stop 33 at the end of the opening movement of the actuator, which takes place in a counter-clockwise direction relatively to the stationary contact 41, as viewed in FIGS. 5 and 6. In this open position the cam 55 (which as above mentioned is made of insulating material) lies in part, between the stationary and movable contact 41 and 54 and physically holds these contacts apart against the downward component of the spring force. At the same time the end-piece 51 of the resilient member 44 is held by the actuator resilience of such member in engagement with the oblique wall 52 of the recess 39, part of the curved portion 49 of the resilient member lying in engagement with the inner face 57 of the cam.
To effect the closing of the switch from this open po sition, the actuator shaft 18 is operated to rotate the disc 19 carrying the cam 55 in the clockwise direction (in FIG. 6). This causes the inner face 57 of the cam to ride over the convex portion 50 of the third arm of the resilient member, and thereby to force the endpiece 51 to make a short upward sliding movement along the oblique wall 52 of the recess and thereafter to separate from such oblique wall (to the position shown in FIG. 8) in a direction to distort the resilient member still further from its normal unstressed shape, thereby imparting additional loading to such member. This movement continues until the operative corner 56 of the cam has moved sufficiently far ground the convex corner portion 50 to permit such convex portion to escape past the comer 56 of the cam under the action of the increased spring force. Immediately such escape takes place the convex portion will move at high speed to bring the movable contact 54 into engagement with the stationary contact 41. The point on the stationary contact 41, with which the movable contact 54 engages, is at a position thereon towards the free end of the stationary contact. The parts are now in the closed position of the switch, as shown in FIG. 5.
To open the switch from such closed position, the actuator shaft 18 is operated to rotate the disc 19 in the counter-clockwise direction (as viewed in FIGS. and 6). This causes the corner 56 of the cam 55 to engage with a point on the straight end-piece 51 of the movable contact member 44 near the convex comer-piece 50, and to force such end-piece 51 out of engagement with the oblique wall 52 of the recess 39 in a direction to apply additional loading to the resilient member 44. At the same time the movable contact 54 makes a sliding movement along the surface of the stationary contact 41. The parts are now in the positions shown in FIG. 3. Further movement of the cam 55, causes the movable contact 54 to separate from the stationary contact 41, and the increased spring force of the movable contact member 44 causes the convex portion of such member to slide at high speed along the inner surface 57 of the cam 55 into the open position (shown in FIG. 6) in which the end-piece 51 of the member engages with the oblique wall 52 of the recess.
The various paths of movement of the movable contact 54 are indicated in the diagram of FIG. 10. In the open position of the switch such contact is in the position indicated at 58 in FIG. 10. During the closing movement, such contact first moves from 58 and 59 and thereafter from 59 to engage with the stationary contact at the point 60. This is the closed position of the switch. During the opening movement, the movable contact 54 first slides along the surface of the stationary contact 41 from the point 60 to the point 61, and then separates from the stationary contact and moves back to the point 58 in the open position of the switch.. The various paths of movement of the movable contact thus together form a pattern somewhat resembling a butterfly shape.
The chief advantage of this complex movement is that the point of engagement 60 of the movable contact with the stationary contact during the closing movement of the switch is spaced apart from the point 61 of the stationary contact at which the movable contact separates from the stationary contact during the opening movement. This is advantageous for two reasons, first that the arcing which takes place just before the contacts engage during the closing movment will occur at a point on the stationary contact spaced apart from that at which arcing occurs on separation of the contacts during the opening movement, so that the harmful effects on the contact surface of pitting due to arcing are not concentrated at one point, as they normally are in switches in which the opening movement takes place along exactly the same path as the closing movement but in the opposite direction. The second advantage of the arrangement is that the sliding movement of the contacts in the early stage of the opening movement has the effect of wiping away the products of arcing, so that the contacts have a self-cleaning affect. While there is a relatively wide spacing between the arcing points on the stationary contact 41, the slight curvature of the portion 49 of the movable contact also causes a smaller spacing apart of the arcing points on the movable contact, so that the advantageous effects apply to both of the cooperating contacts, whereby the useful life of both contacts, before replacement is needed, is greatly increased.
Yet another advantage of the arrangement described arises from the fact that additional loading is provided for the resilient member just before the operative movements take place. This means that the resilient member 44 can safely be stressed nearly to its elastic limit, for a spring can withstand such high stressing (without serious harmful effects) provided that it is only exposed thereto for very brief periods and is not continuously held in the highly stressed condition. It thus becomes possible to obtain very high speeds of movement of the movable contact, at the comparatively rare occasions when the switch is operated, without serious harmful effect on the resilient member, thus making for longer useful life of the resilient member, while still obtaining the maximum speeds of movement, which the spring is capable of producing. Further, since the movable contact 44 and the stationary contact 41 are integral with their respective terminals 53, 43, the switch employs fewer separate parts and is simpler to manufacture than the prior known switches for a similar purpose.
Owing to the spacing of the cam at a substantial radial distance from the axis of rotation, only a small rotational movement of the actuator is required for the operation of the switch, and the remaining portion of the possible rotational movement of the actuator, extending to nearly a complete revolution is available, while the switch is spring-held in its closed position, for the control by the actuator of the wiping movement of the movable contactor 20 over the resistance element 12 for varying the effective resistance value thereof in the well-known manner.
It will be appreciated that the foregoing arrangement has been described by way of example and that various modifications may be made within the scope of the invention as defined in the appended claims. Thus for example the switch may be used alone for any suitable switching purposes, instead of in combination with the resistance. Again, although rotary operating movments are preferred, the invention is not limited thereto.
What is claimed as new and desired to be secured by letters patent of the United States is:
1. An electric switch comprising a housing, a stationary contact supported in the housing, a resilient member having a movable contact and a terminal integral therewith supported in the housing, both the movable contact and the terminal being made from the same material and having the same thickness, said movable contact being preformed to effect a bias against said stationary contact, a camming surface integral with the housing and adjacent to the movable contact, a movable cam mounted for movement in an interference path with said'resilient member for moving the movable contact into and out of operative engagement with the stationary contact, the camming surface controlling movement of the movable contact toward and away from the stationary contact and biasing the movable contact toward the stationary contact when the cam is spaced from the movable contact, said movable contact being mounted for movement both along said stationary contact and away from said stationary contact, and actuating means for effecting movements of the cam whereby upon moving the cam in one direction the cam engages the movable contact increasing the force between the movable contact and the stationary contact until the movable contact is displaced into a labile neutral position storing energy therein, the movable contact after passing through the labile neutral position rapidly moving with a snap action motion in a direction opposite to the direction of movement of the cam.
2. The electric switch of claim 1 wherein said resilient member comprises a metal strip having a portion fixedly secured on an insulating disk and forming said terminal.
3. The electric switch of claim 2 wherein the cam physically engages and is disposed between said movable contact and said stationary contact when the switch is in the off position, and said stationary contact has a terminal integral therewith.
4. An electric switch comprising an insulating baseplate, a stationary contact and a resilient member supported on said base-plate, said resilient member having a movable contact and a terminal integral therewith, both the movable contact and the terminal being made from the same material and having the same thickness, said movable contact being preformed to effect a bias against said stationary contact, a caming surface disposed on the base-plate adjacent to the movable contact and integral therewith, a movable cam mounted for rotation in an interference path with said resilient member for moving the movable contact into and out of the operative engagement with the stationary contact, the caming surface controlling movement of the movable contact toward and away from the stationary contact and biasing the movable contact toward the stationary contact when the cam is spaced from the movable contact, and actuating means for effecting movements of the cam, said cam being located at a position widely spaced from its axis of rotation whereby only relatively small movements movments are required of the actuating means for effecting the operative movements of the cam whereby upon moving the cam in one direction the cam engages the movable contact increasing the force between the movable contact and the stationary contact until the movable contact is displaced into a labile neutral position storing energy therein, the movable contact after passing through the labile neutral position rapidly moving with a snap action motion in a direction opposite to the direction of movement of the cam.
5. The electric switch of claim 4 wherein said resilient member comprises a metal strip having the shape of a three sided rectangle, one of the sides being fixedly secured to said base-plate and having a portion extending through said base-plate forming a terminal.
6. The electric switch of claim 4 wherein said cam physically separates the movable contact from the stationary contact when the switch is in the off position.
7. The electric switch of claim 4 wherein said baseplate has a recess formed therein and said resilient member and said stationary contact are mounted in said recess, said movable contact having a curved portion projecting out of said recess for engagement with said cam whereby said cam can move past the remainder of said resilient member without engagement therewith.
8. The electric switch of claim 5 wherein said movable contactor is in spaced parallel relationship to said one of the sides.
9. The electric switch of claim 4 wherein the engagement of the movable contact and the stationary contact during the closing movement of the switch takes place at a point on the stationary contact surface spaced from the point of said surface at which separation of the contacts occurs during opening of the switch.
10. The electric switch of claim 4 wherein said cam moves over a convex portion of said resilient member thereby forcing said convex portion in a direction to impart additional loading to the resilient member.
11. An electric switch comprising an insulating baseplate containing a shaped recess, a stationary contact supported in said recess in said base-plate and having a terminal integral therewith, and a resilient member supported in said recess in said base-plate, said resilient member comprising a C-shaped metal strip having a movable contact and a terminal integral therewith, said resilient member and said stationary contact containing portions extending out of said recess, said movable contact and integral terminal being made from the same material and having the same thickness and being preformed to efl'ect a bias against said stationary contact, a camming surface forming a wall of said recess and disposed adjacent to the movable contact and integral therewith, a movable cam mounted for rotation in an interference path with said resilient member for moving the movable contact into and out of the operative engagement with the stationary contact, said cam physically separating the movable contact from the stationary contact when the switch is in the off position, the camming surface controlling movement of the movable contact toward and away from the stationary contact and biasing the movable contact toward the stationary contact when the cam is spaced from the movable contact, and actuating means for effecting movements of the cam, said cam being located at a position widely spaced from its axis of rotation whereby only relatively small rotary movements are required of the actuating means for effecting the operative movements of the cam whereby upon moving the cam in one direction the cam engages the movable contact increasing the force between the movable contact and the stationary contact until the movable contact is displaced into a labile neutral position storing energy therein, the movable contact after passing through the labile neutral position rapidly moving with a snap action motion in a direction opposite to the direction of movement of the cam, said stationary contact containing a first location engaging the movable contact during the closing of the switch and a second location spaced from said first location at which separation of the contacts occurs during opening of the switch.
12. An electric switch comprising an insulating baseplate containing a shaped recess, a stationary contact supported in said recess in said base-plate, and a resilient member supported in said recess in said base-plate, said resilient member having a movable contact and a terminal integral therewith, said resilient member and said stationary contact containing portions extending out of said recess and both the movable contact and the terminal being made from the same material and having the same thickness, said movable contact being preformed to effect a bias against said stationary contact, a camming surface forming a wall of said recess and disposed adjacent to the movable contact and integral therewith, a movable cam mounted for rotation in an interference path with said resilient member for moving the movable contact into and out of the operative engagement with the stationary contact, the camming surface controlling movement of the movable contact toward and away from the stationary contact and biasing the movable contact toward the stationary contact when the cam is spaced from the movable contact, and actuating means for effecting movements of the cam, said cam being located at a position widely spaced from its axis of rotation whereby only relatively small rotary movements are required of the actuating means for effecting the operative movemnts of the cam whereby upon moving the camin movements direction the cam engages the movable contact increasing the force between the movable contact and the stationary contact until the movable contact is displaced into a labile neutral position storing energy therein, the movable contact after passing through the labile neutral position rapidly moving with a snap action motion in a direction opposite to the direction of movement of the cam.

Claims (12)

1. An electric switch comprising a housing, a stationary contact supported in the housing, a resilient member having a movable contact and a terminal integral therewith supported in the housing, both the movable contact and the terminal being made from the same material and having the same thickness, said movable contact being preformed to effect a bias against said stationary contact, a camming surface integral with the housing and adjacent to the movable contact, a movable cam mounted for movement in an interference path with said resilient member for moving the movable contact into and out of operative engagement with the stationary contact, the camming surface controlling movement of the movable contact toward and away from the stationary contact and biasing the movable contact toward the stationary contact when the cam is spaced from the movable contact, said movable contact being mounted for movement both along said stationary contact and away from said stationary contact, and actuating means for effecting movements of the cam whereby upon moving the cam in one direction the cam engages the movable contact increasing the force between the movable contact and the stationary contact until the movable contact is displaced into a labile neutral position storing energy therein, the movable contact after passing through the labile neutral position rapidly moving with a snap action motion in a direction opposite to the direction of movement of the cam.
2. The electric switch of claim 1 wherein said resilient member comprises a metal strip having a portion fixedly secured on an insulating disk and forming said terminal.
3. The electric switch of claim 2 wherein the cam physically engages and is disposed between said movable contact and said stationary contact when the switch is in the off position, and said stationary contact has a terminal integral therewith.
4. An electric switch comprising an insulating base-plate, a stationary contact and a resilient member supported on said base-plate, said resilient member having a movable contact and a terminal integral therewith, both the movable contact and the terminal being made from the same material and having the same thickness, said movable contact being preformed to effect a bias against said stationary contact, a caming surface disposed on the base-plate adjacent to the movable contact and integral therewith, a movable Cam mounted for rotation in an interference path with said resilient member for moving the movable contact into and out of the operative engagement with the stationary contact, the caming surface controlling movement of the movable contact toward and away from the stationary contact and biasing the movable contact toward the stationary contact when the cam is spaced from the movable contact, and actuating means for effecting movements of the cam, said cam being located at a position widely spaced from its axis of rotation whereby only relatively small movements movments are required of the actuating means for effecting the operative movements of the cam whereby upon moving the cam in one direction the cam engages the movable contact increasing the force between the movable contact and the stationary contact until the movable contact is displaced into a labile neutral position storing energy therein, the movable contact after passing through the labile neutral position rapidly moving with a snap action motion in a direction opposite to the direction of movement of the cam.
5. The electric switch of claim 4 wherein said resilient member comprises a metal strip having the shape of a three sided rectangle, one of the sides being fixedly secured to said base-plate and having a portion extending through said base-plate forming a terminal.
6. The electric switch of claim 4 wherein said cam physically separates the movable contact from the stationary contact when the switch is in the off position.
7. The electric switch of claim 4 wherein said base-plate has a recess formed therein and said resilient member and said stationary contact are mounted in said recess, said movable contact having a curved portion projecting out of said recess for engagement with said cam whereby said cam can move past the remainder of said resilient member without engagement therewith.
8. The electric switch of claim 5 wherein said movable contactor is in spaced parallel relationship to said one of the sides.
9. The electric switch of claim 4 wherein the engagement of the movable contact and the stationary contact during the closing movement of the switch takes place at a point on the stationary contact surface spaced from the point of said surface at which separation of the contacts occurs during opening of the switch.
10. The electric switch of claim 4 wherein said cam moves over a convex portion of said resilient member thereby forcing said convex portion in a direction to impart additional loading to the resilient member.
11. An electric switch comprising an insulating base-plate containing a shaped recess, a stationary contact supported in said recess in said base-plate and having a terminal integral therewith, and a resilient member supported in said recess in said base-plate, said resilient member comprising a C-shaped metal strip having a movable contact and a terminal integral therewith, said resilient member and said stationary contact containing portions extending out of said recess, said movable contact and integral terminal being made from the same material and having the same thickness and being preformed to effect a bias against said stationary contact, a camming surface forming a wall of said recess and disposed adjacent to the movable contact and integral therewith, a movable cam mounted for rotation in an interference path with said resilient member for moving the movable contact into and out of the operative engagement with the stationary contact, said cam physically separating the movable contact from the stationary contact when the switch is in the off position, the camming surface controlling movement of the movable contact toward and away from the stationary contact and biasing the movable contact toward the stationary contact when the cam is spaced from the movable contact, and actuating means for effecting movements of the cam, said cam being located at a position widely spaced from its axis of rotation whereby only relatively small rotary movements are requiRed of the actuating means for effecting the operative movements of the cam whereby upon moving the cam in one direction the cam engages the movable contact increasing the force between the movable contact and the stationary contact until the movable contact is displaced into a labile neutral position storing energy therein, the movable contact after passing through the labile neutral position rapidly moving with a snap action motion in a direction opposite to the direction of movement of the cam, said stationary contact containing a first location engaging the movable contact during the closing of the switch and a second location spaced from said first location at which separation of the contacts occurs during opening of the switch.
12. An electric switch comprising an insulating base-plate containing a shaped recess, a stationary contact supported in said recess in said base-plate, and a resilient member supported in said recess in said base-plate, said resilient member having a movable contact and a terminal integral therewith, said resilient member and said stationary contact containing portions extending out of said recess and both the movable contact and the terminal being made from the same material and having the same thickness, said movable contact being preformed to effect a bias against said stationary contact, a camming surface forming a wall of said recess and disposed adjacent to the movable contact and integral therewith, a movable cam mounted for rotation in an interference path with said resilient member for moving the movable contact into and out of the operative engagement with the stationary contact, the camming surface controlling movement of the movable contact toward and away from the stationary contact and biasing the movable contact toward the stationary contact when the cam is spaced from the movable contact, and actuating means for effecting movements of the cam, said cam being located at a position widely spaced from its axis of rotation whereby only relatively small rotary movements are required of the actuating means for effecting the operative movemnts of the cam whereby upon moving the cam in movements direction the cam engages the movable contact increasing the force between the movable contact and the stationary contact until the movable contact is displaced into a labile neutral position storing energy therein, the movable contact after passing through the labile neutral position rapidly moving with a snap action motion in a direction opposite to the direction of movement of the cam.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0131100A1 (en) * 1983-06-08 1985-01-16 PREH, Elektrofeinmechanische Werke Jakob Preh Nachf. GmbH & Co. Electronic brightness control apparatus
WO2012113102A1 (en) * 2011-02-25 2012-08-30 Honeywell International Inc. Electrical switch system and electrical switch assembly

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US2059712A (en) * 1934-03-05 1936-11-03 Chicago Telephone Supply Co Control device
US3259709A (en) * 1963-07-24 1966-07-05 Plessey Uk Ltd Snap action switch devices
US3324261A (en) * 1965-08-06 1967-06-06 Mallory & Co Inc P R Snap switch means
US3349359A (en) * 1964-12-18 1967-10-24 Templeton Coal Company Electrical heating elment
US3370261A (en) * 1965-01-04 1968-02-20 Cts Corp Electrical switch and combination electrical resistor and switch

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2059712A (en) * 1934-03-05 1936-11-03 Chicago Telephone Supply Co Control device
US3259709A (en) * 1963-07-24 1966-07-05 Plessey Uk Ltd Snap action switch devices
US3349359A (en) * 1964-12-18 1967-10-24 Templeton Coal Company Electrical heating elment
US3370261A (en) * 1965-01-04 1968-02-20 Cts Corp Electrical switch and combination electrical resistor and switch
US3324261A (en) * 1965-08-06 1967-06-06 Mallory & Co Inc P R Snap switch means

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0131100A1 (en) * 1983-06-08 1985-01-16 PREH, Elektrofeinmechanische Werke Jakob Preh Nachf. GmbH & Co. Electronic brightness control apparatus
WO2012113102A1 (en) * 2011-02-25 2012-08-30 Honeywell International Inc. Electrical switch system and electrical switch assembly

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