Universal mount contact block with reversible protected wiring terminals

A reconfigurable contact block usable for at least DIN rail and panel mount applications. The contact block's wiring compartments have reversible wiring terminals and reversible, interchangeable protective covers. Lateral wiring ports in each cover guide inserted wires to the covered terminal, and an axially facing cover opening provides tool access to the terminal.

FIELD OF THE INVENTION

The invention relates to electric power switches and, in particular, to the contact block portion of a switch, which houses electrical contacts and conductors and has terminals for connecting external wiring to the conductors.

BACKGROUND OF THE INVENTION

Contact blocks have a protruding operating member such as a shaft (reciprocating or rotary) and are specifically built for panel mounting or for DIN rail mounting, but not for both. A contact block built for panel mounting typically is secured against the back of a panel, the operator shaft protruding to the front of the panel through a hole. The close proximity of the panel necessitates rear-facing terminal screws for making the wiring connections. A contact block built for DIN rail mounting typically has a rear-facing slot that embraces a DIN rail. Front-facing terminal screws are provided because the DIN rail and/or its supporting structure would block access to rear-facing terminal screws.

SUMMARY OF THE INVENTION

The invention concerns a reconfigurable contact block that can be mounted at its front (operator) end behind a panel or at its rear end to a DIN rail or other support. The contact block's wiring compartments have reversible wiring terminals and reversible, interchangeable protective covers.

A contact block according to the invention comprises a casing having an axially facing front end, an axially facing rear end, a plurality of sides and internal switching contacts. At least one wiring compartment located at one side of the casing has an open front end and an open rear end. A switch conductor extends laterally into the wiring compartment and substantially divides it into front and rear wiring chambers. An axially extending wiring terminal is in one of the wiring chambers and is connected to the switch conductor, and a removable cover is attached to the casing over the wiring compartment. The cover comprises at least one lateral wiring port axially offset from the switch conductor and an axially facing access opening near the wiring port. The cover and the casing have biaxially symmetrical mating portions that enable reversible attachment of the cover to the casing in either of two orientations so that the wiring chamber in which the wiring terminal is located is accessible by a wire through the wiring port and the wiring terminal is accessible by a tool through the access opening.

The contact block preferably has two wiring compartments located at opposite sides of the casing and two covers, one for each wiring compartment. The covers are substantially identical and the cover-mating portions of the casing are substantially identical so that either cover can be attached to the casing over either wiring compartment in either orientation.

Each wiring compartment preferably comprises a lateral end wall having at least one pair of axially spaced guide ports. Each guide port communicates with a respective wiring chamber and the wiring port of the cover is aligned with one of those guide ports when the cover is attached to the casing.

DETAILED DESCRIPTION OF THE INVENTION

As used in this application, terms such as “front,” “rear,” “side,” “top,” “bottom,” “above,” “below,” “upward” and “downward” are intended to facilitate the description of the contact block of the invention, and are not intended to limit the structure of the invention to any particular position or orientation.

Referring toFIGS. 1-3,8and9, a contact block according to the invention comprises a molded casing having a central core4with a front end6facing axially away from the core and a rear end8facing axially away from the core in the opposite direction. Screws9hold the core components together. The core also has a first side10; a second side12opposite the first side; a third side14extending between the first and second sides; and a fourth side16opposite the third side. An axially movable input shaft (plunger)18extends from a boss20at front end6. Two holes22in front end6receive mounting screws S for securing the contact block to and against a panel (not shown), which typically has a hole through which boss20and shaft18would extend. Rear end8also has two screw holes24for alternate mounting of a DIN rail clip21(seeFIGS. 10-13), which has a slot23adapted to embrace a DIN rail. Alternatively, rear end8may be formed with an integral DIN rail slot.

As seen inFIG. 9, an axially movable brush28within the core carries two brush contacts26at its opposite ends. The actuator for this brush contact assembly is conventional and comprises an axially movable contact basket25having an aperture through which brush28extends; a balance contact spring27between contact basket25and the front face of brush28; and an actuation spring29between contact basket25and the rear end8of the core. Brush contacts26engage respective stationary contacts30carried at the inner ends of respective conductors32. A pushbutton operator (not shown) on the outer end of shaft18provides user input for actuation.FIG. 9shows an example of a normally closed (NC) actuator arrangement: inward movement of shaft18engages contact basket25and causes the contacts26,30to separate, breaking the circuit.FIG. 1Ashows an example of a normally open (NO) actuator arrangement: inward movement of shaft18engages contact basket25and causes contacts26,30to close, making the circuit. It should be understood that the invention is not limited to any particular type of internal actuator or contact arrangement, or to the type of external operator that provides user input to the actuator.

Referring toFIGS. 2,3and9, each side10,12of the core has an integrally formed wiring compartment34defined by parallel tapered extensions36of sides14,16and an interconnecting lateral end wall38. The edges of extensions36and end wall38define a front opening35and a rear opening33for tool access to the wiring compartment. Each end wall38has a pair of front wire guide ports39and a pair of rear wire guide ports41. Referring toFIGS. 1A and 9, each conductor32extends laterally outward into its respective wiring compartment34, substantially dividing it into a front wiring chamber40adjacent guide ports39and a rear wiring chamber42adjacent guide ports41. Thus, each front wire guide port39serves to guide the end of a wire into front wiring chamber40and each rear wire guide port41serves to guide the end of a wire into rear wiring chamber42.

A terminal assembly for each wiring compartment34is connected to conductor32in one of the wiring chambers depending on the application: in rear wiring chamber42for panel mounting as shown inFIGS. 1A and 9; in front wiring chamber40for DIN rail mounting as shown inFIG. 13. Each terminal assembly is conventional and comprises a terminal screw44that engages a threaded hole46in conductor32and preferably includes a lock washer49beneath the head of the screw and a roughened wire clamping washer48, which can clamp one or two wires inserted through the wire guide port(s)39or41.

Referring toFIGS. 2-7and14, each wiring compartment34is provided with a protective molded cover50that snaps onto casing4and is held in place by four corner snap tabs52that respectively engage four recesses54in casing extensions36. The sloped edges56of extensions36act as ramps that spread opposing tabs52apart as cover50is pressed onto the wiring compartment until the tabs reach and engage recesses54. Cover50can be pried off if necessary by inserting and twisting a flat screwdriver blade or similar tool in the gap58between the casing and the cover. Cover50also has a solid end wall60, a U-shaped terminal access opening62in the opposite end wall64and a side-by-side pair of wiring ports66in its lateral end wall68that are axially offset toward opening62.

Cover50has a universal configuration that enables it to be installed over either wiring compartment34in either of two orientations as required by the mounting application, i.e., as a function of which wiring chamber40,42houses the terminal assembly. For panel mounting, cover50would be installed with its opening62facing rearward to enable access to terminal screw44in rear wiring chamber42(seeFIGS. 1,1A,2,3,8and9). For DIN rail mounting, cover50would be installed with its opening62facing forward to enable access to terminal screw44in front wiring chamber40(seeFIGS. 10-13). In either orientation, cover wiring ports66are aligned with one pair of wiring chamber guide ports39or40so that one or two wires W can be inserted through the aligned ports and into the appropriate wiring chamber, where they can be clamped by tightening the terminal screw44(seeFIG. 1A).

The positional versatility of cover50is due to the biaxial symmetry of the mating portions of the cover and the casing, as is evident inFIGS. 2-9,13and14. The mating portions of the casing, which are identical on each side10,12, comprise (1) the laterally protruding contoured edge37of each side extension36, which has a double reverse curved and straight profile, and (2) the four tab-receiving recesses54. These casing features collectively are symmetrical about a longitudinal axial plane, i.e., one containing the axis of shaft18and bisecting both wiring compartments34. They are also symmetrical about a plane perpendicular to that axial plane and bisecting both wiring compartments between guide ports39and41. The mating portions of the cover comprise (1) its two contoured edges67, which are substantially congruent with the contoured edges37of the casing, and (2) its four snap tabs52, which are axially and laterally spaced to fit into recesses54. These mating cover features collectively are symmetrical about the same two perpendicular planes.

While a preferred embodiment has been chosen to illustrate the contact block of the invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined by the appended claims.