Tap Switch

Abstract

A simplified tap switch having a snap action includes a rocker adapted to be pivoted by a tap handle, which is demountably secured to the rocker, with the underportion of the rocker engaging a movable contact arm which rests in a cradle of a link, the link being pivotally secured to a stationary terminal of the switch. A coil spring biases the movable contact arm into the cradle of the link and is arranged on protruding elements so that the pivotal movement of the rocker causes an over-center snap action which moves the movable contact arm between two stable positions.

Parent Case Text

This application is a continuation-in-part of our copending application Ser. No. 826,339 filed May 21, 1969.

Description

The present invention relates to a tap switch, or touch switch, as such switches are sometimes called, which is a wall switch or the like intended to be mounted in a standard outlet box and which can be actuated by relatively slight movement, i.e., tapping.

A switch, constructed pursuant to the present invention, provides advantages with respect to simplity of construction, operational reliability, and reduced costs of manufacture. Additionally, the switch of the invention has a demountable tap handle which is a desirable commercial feature since it provides for simple interchange of tap handles of different color or design.

In the following description, reference to a "tap switch" is not intended to be limiting in any respects. Those skilled in the art will recognize that certain features and advantages of the invention are applicable to switches other than those generally referred to as tap or touch switches.

The invention is described in detail below with reference to the attached drawings, wherein:

FIG. 1 is a side elevational view of a preferred embodiment of the invention;

FIG. 2 is a side view, partially in section, of the preferred embodiment of the invention;

FIG. 3 is a sectional view along the line 3--3 of FIG. 2;

FIG. 4 is a sectional view along the line 4--4 of FIG. 2;

FIG. 5 is a detailed top view, partially in section, showing the means for operating the contacts;

FIG. 6 is an exploded perspective view showing the contact and support arrangement pursuant to the preferred embodiment of the invention; and

FIG. 7 is a top view showing the means for demountable attachment of the tap handle.

Referring to the drawings, the switch is contained in a two-part housing which includes a body portion 10 and cover 12. As standard mounting bracket 14 is secured to cover 12 by left and right rivets, 16 and 18 respectively, the mounting bracket 14 provides a means to secure the switch within a standard outlet box so that the switch can be well-mounted. At this juncture, it is noted that the terms "left" and "right" are used only for purposes of explanation and are used with respect to FIGS. 2 and 3. The terms "upper" and "lower" in the following description are used in the same sense and obviously are not intended to be limiting in any respect.

A pivotal rocker 20 is mounted within the body 10 and connected to a tap handle 22 which is the actuator means for the switch. The tap handle 22 is generally rectangular and shaped in longitudinal cross-section (as shown in FIGS. 1 and 2) to form a large oblique angle between its left and right halves. Left and right tubular protrusions 24 and 26, bearing crowns 27 and 29 respectively, extend downwardly into left and right square prismatic recesses 28 and 30 within the rocker 20 to form a single unitary construction. Crowns 27 and 29 overlap the lower edges A and B of rocker 20 thereby fastening tap handle 22 firmly in place. The crowns are deformable and therefore tap handle 22 can be removed by pulling the handle body in a direction away from rocker 20. The square prismatic recesses 28 and 30 are adapted to guide crowns 27 and 29 therein, thereby facilitating the interchange of tap handles. To replace a handle, tubular protrusions 24 and 26 bearing deformable crowns 27 and 29 are urged toward the lower edges A and B of rocker 20 until they emerge from the square prismatic recess and overlap lower edges A and B of rocker 20. Two oppositely disposed axles 32 and 34 are integrally formed with rocker 20 and extend into fitted retention portions formed between cover 12 and body 10 by triangular recesses 36 in cover 12 and corresponding recesses 38 (FIGS. 2 and 3) in a pair of mounting portions 40 which protrude upwardly from the sides of the body 10.

The stationary terminals of the switch are shown most clearly in FIGS. 1 and 3. The left terminal comprises a plate 42 which is accessible from the exterior of the switch body 10 and a transverse terminal extension 44 which extends inwardly into the body. A threaded aperture 46 is tapped into the plate 42 to receive a terminal screw 48 in order to connect the switch in a circuit. A square opening 50 is provided at the innermost extremity of extension 44 for purposes described in the following discussion. The right-hand terminal is similar and includes an external plate 52 from which a transverse extension 84 extends into the body portion 10. A tapped hole 54 is provided in the plate 52 to receive the second terminal screw 56. At the innermost extremity of extension 54, a hole 56 is formed to receive the stem of a mushroom-shaped contact 58 (see also FIG. 2).

The elements of the switch construction primarily responsible for the simplified construction are shown most clearly in FIG. 6. These elements include a stationary link 60 and a movable contact arm 62. The link 60 includes at its left end a downwardly bent ear 64 which in combination with the adjacent portions of the link secure the link to terminal 42 when the ear 64 is received within the square opening 50 of the left terminal extension 44. The link 60 further includes a bifurcated cradle formed by first and second arms 66 and 68 respectively, separated by a cutout portion 69. The arms 66 and 68 are generally U-shaped with their open end diverging from respective floor portions 66a and 68a.

The bifurcated cradle portion of link 60 longitudinally is located in body 10 by means of transverse ridges 94 and 95.

The movable contact arm 62 includes an elongated extension member 70 at the free end of which a contact 72 is mounted. Integrally formed with member 70 is a transverse grasping portion 74 the central portion 76 of which is stamped out to provide a four-walled structure including vertical walls 77a and 77b. The bottom of grasping portion 74 terminates in shoulders 79a and 79b which correspond in width to arms 66 and 68, respectively, and are adapted to be retained therein.

The link 60 is electrically and mechanically coupled to the left terminal extension 44 by inserting ear 64 through the opening 50, with the cradle of link 60 extending toward the right side of the switch. The shoulders 79a and 79b of the grasping member 74 are nested within the cradle formed by the arms 66 and 68. The upper portion of the grasping member 74 is received within a retaining slot 82 of a cylindrical extension 80 depending downwardly from the rocker body 20. A coil spring 84 coiled around the cylinder 80, and pivotally seated in tilted attitude on projecting members 90 and 91, is under compression, and urges the movable contact arm 62 away from the rocker 20, thus serving as the compression member for an over-center snap action movement. Cross bar 93 on coil spring 84 oscillates diametrically from one side of slot 82 to the other as rocker 20 is pivoted back and forth and therefore it will be understood that coil spring 84 has a sufficient inside diameter to provide a loose fit around cylinder 80.

The arrangement of the spring 84, link 60 and contact arm 62 is such that when the switch is in the position illustrated in FIG. 2, the grasping member 74 is pivoted within the cradle formed by arms 66 and 68. When the right-hand side of tap handle 22 is depressed, causing the rocker 20 to pivot clockwise (as viewed in FIG. 2), the actuator construction will pass through an over-center position at which the force of the spring 84 will abruptly urge the grasping member 74 to the left causing the contact arm 62 to transfer to its other stable position in which contact 72 is in electrical contacting relationship with the stationary contact 58. Incident to this operation, the balance of coil spring 84 on axially projecting members 90 and 91 is easily overcome when tap handle 22 is depressed, thus pivoting spring 84 from one fixed tilting position on rocker 20 to the opposing fixed tilting position. This movement aids in overcoming the inertia of rocker 20 and grasping member 74, thereby reducing the tendency for the switch to stick in a central position, and making the operation smoother.

The invention has been described for use with a single-pole, single-throw switch. Obviously, the invention could be used with a double-throw switch by simply incorporating a second stationary contact (such as 58) beneath the elongated extension member 70 of contact arm 62, the second contact being adapted to engage, for example, an extension of movable contact 72. It is further contemplated that the invention may be used as a three-way or four-way switch. In the latter case, two constructions as illustrated herein (modified for double-throw action) would be provided in a side-by-side relationship with a single rocker arm being used to actuate both of the corresponding switches simultaneously. Another embodiment of the invention includes a suitable neon lamp mounted behind tap handle 22 in a recessed portion of rocker 20 to provide a lighted handle tap switch. The lamp is mounted so that it will remain in place despite the rocker movement of tap handle 22. The lamp is connected via a ballast resistor to the power source so that the tap handle 22 is illuminated when the tap switch is in the open circuit condition.

Claims

What is claimed is:

1. A snap action switch comprising an insulated structure,

a first stationary terminal structure including a transverse terminal extension plate, a conductive link member and cradle member,

said transverse terminal extension plate bearing a square aperture at its innermost extremity,

said conductive link member having a downwardly bent ear at one end thereof which is received within said square aperture located on said transverse terminal extension plate

said ear acting in combination with adjacent link surfaces to secure said conductive link to said first stationary terminal structure,

said conductive link member having a free end opposite to the secured end which terminates in said cradle member,

a movable contact arm including an elongated extension member and a transverse member joined to one end thereof, the transverse member being received for rocking movement in said cradle member with said extension member extending away from said cradle member, and a movable contact near the free end of the extension member,

a second stationary terminal structure having a fixed contact in the path of said movable contact,

a rocker pivotally mounted in said housing including a post portion extending toward said transverse member of said movable contact arm,

said post portion of said rocker terminating in a free end provided with an open slot-shaped recess adapted to freely receive a portion of said transverse member of said movable contact arm therein, and

a coil spring tiltably seated at one end on a pair of opposed projecting members provided on said rocker at the base of said post portion so as to extend circumferentially about said post portion in spaced relationship thereto and terminating at the other end in a cross member which extends through said slot-shaped recess adjacent and generally parallel to said transverse member of said movable contact arm, said coil spring thereby being compressed between said rocker projecting members and said movable arm transverse member,

whereby upon pivoting said rocker member said cross member of said coil spring oscillates diametrically between the sides of said slot-shaped recess to thereby urge said transverse member of said movable contact arm from one fixed tilted position to an opposed fixed tilted position.

2. A snap action switch as recited in claim 1, including

a tap handle having means for demountable engagement with said rocker, and wherein

said rocker includes a pair of shaped recesses in coaxial alignment with and encompassing a portion of said transverse member of said movable contact arm, and

said means for demountable engagement of said tap handle with said rocker comprises a pair of tubular protrusions bearing deformable crowns,

said tubular protrusions extending downwardly from said tap handle and slidably mating with said shaped recesses until said deformable crowns overlap the lower edges of said rocker, thereby fixing said tap handle to said rocker.

3. A snap action switch as claimed in claim 1, wherein the coil of said spring adjacent said cross member is axially spaced from the next preceding coil thereof.

4. A snap action switch as claimed in claim 1, wherein

said cradle member is bifurcated so as to include two cradle arms, and

said transverse member includes top, bottom, and two side walls defining a central opening,

said bottom wall being received for rocking movement in said cradle member,

said top wall being received in said slot-shaped recess and bearing against said linear portion of said coil spring, and

said extension member secured to said bottom wall and extending between the arms of said bifurcated cradle member.