Door Hinge Assembly With Fixed Pivot Pin for an Enclosure for Electrical Apparatus and Enclosure Incorporating Same

1. Field of the Invention

This invention relates to a hinge assembly for doors on enclosures for electrical apparatus such as switchgear, and to such enclosures incorporating the hinge assembly. More particularly, it relates to a hinge assembly especially suitable for wide doors in which the hinge pin is fixed to either the door or the door jamb and is clamped by a hinge housing secured to the other component of the enclosure.

2. Background Information

The enclosures for electrical apparatus, such as for instance switchgear, include doors which are often short and wide. Such doors can have a width which is as much as four to five times the height of the door. Conventional door hinges, such as those with a hinge pin extending through aligned bores in interleaved bosses on flanges secured to the door and the door jamb, have inherent tolerances that produce excessive sag in the wide doors.

There is a need, therefore, for an improved hinge assembly for such enclosures for electrical apparatus, and the enclosures incorporating them, which eliminates the excessive sag commonly found in current equipment.

There is a related need for such hinge assemblies and enclosures which are simple and easy to manufacture and install.

There is a particular need for such hinge assemblies and enclosures which do not require machining or time consuming alignment to eliminate the excessive sag.

These needs and others are satisfied by the invention which is directed to a hinge assembly comprising of a hinge pin non-rotationally fixed to either the door or the door jamb and a hinge housing fixed to the other of the door and door jamb clamping against the hinge pin with a compression fit which permits relative rotation between the hinge pin and the hinge housing. This hinge housing includes a first member and a second member which clamp the hinge pin between them. The first housing member is an angle member forming an internal corner. The second member is a clamp member which clamps the hinge pin into the internal corner of the angle member. The clamp member has an external corner which nests into the internal corner of the angle member. A corner recess in this external corner which is smaller than the diameter of the hinge pin wedges the hinge pin into the external corner of the angle member. Preferably, the corner recess in the clamping member is an open circle with a diameter smaller than the diameter of the hinge pin.

Preferably, the clamp member has a flat elongated body with first and second clamping flanges projecting from opposite ends and forming spaced apart external corners with aligned corner recesses which nest with the internal corner of the angle member to clamp the hinge pin at two spaced apart locations. Clamp tabs provided on the clamping flanges adjacent the corner recesses are secured to the angle member adjacent the internal corner by clamping fasteners. These clamp tabs are substantially perpendicular to both the clamping flanges and the flat elongated body of the clamp member.

The angle member has first and second elongated, substantially perpendicular, angle flanges joined along a common edge forming the internal corner. An integral mounting flange extends substantially perpendicular to the first angle flange. The clamp tabs on the clamp member are secured to this first angle flange on the angle member by the clamping fasteners. The flat elongated body of the clamp member and the mounting flange of the angle member abut each other and have aligned mounting holes through which mounting fasteners extend to secure the angle member and the clamp member to the other of the door and the door jamb. The angle member and the clamp member are fabricated from sheet material by precision stamping and bending to produce components with very close tolerances. The open circular recesses in the clamping flanges are made tangent to the outer surface of the clamp tabs along one edge of the clamping flange forming the external corner and are also tangent to the other edge of the clamping flange forming the corner. This produces an open circular recess. The diameter of this open circular recess is less than the diameter of the hinge pin so that with the hinge pin received in the open circular recess, it is wedged against the internal corner of the angle member. The compression fit produced by this arrangement is tight enough to eliminate the sag in the door while still permitting relative movement between the hinge pin and the hinge housing.

The invention embraces both the hinge assembly and an enclosure for electrical apparatus including the novel hinge assembly.

A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:

FIG. 1 is an isometric view of a switchgear enclosure incorporating the invention.

FIG. 2 is an exploded isometric view illustrating a hinge assembly in accordance with the invention incorporated into a door for the switchgear enclosure of FIG. 1.

FIG. 3 is a horizontal sectional view through an assembled hinge assembly in accordance with the invention.

FIG. 4 is an exploded isometric view illustrating a hinge assembly in accordance with the invention assembled on the door and showing its mounting to the switchgear enclosure.

The present invention is directed to a hinge assembly for doors such as those used on enclosures for electrical apparatus. It is particularly suitable for short, wide doors and will be described as applied to the short, wide doors providing access to electrical terminations in a switchgear assembly.

Referring to FIG. 1, the switchgear assembly 1 includes a metal cabinet or enclosure 3 having a front compartment 5 containing four cells 7 stacked one on top of another. Each of the cells 7 houses a piece of electrical apparatus (not shown) such as a circuit breaker or metering equipment which are accessible through conventional cell doors 9. Each cell 7 includes an electrical termination strip (also not shown) which is accessible through a separate door 11 at the top of the cell above the cell door 9. These electronic doors 11 are short and wide. For instance, the width of the door 11 can be four to five times or more the height. The doors 11 are hinged along one side edge. When conventional hinges are used for such short, wide doors, they tend to sag.

A hinge assembly 13 in accordance with the invention is illustrated in FIGS. 2-4. The door 11 has a sheet metal frame 15 with flanges 17 and 19 running along the top and bottom edges, and flanges 21 at the hinged end and 23 at the free end. A slot 25 extends through the flange 21 and into the frame 15. A central opening 27 in the frame 15 reduces the weight of the door 11 and can be covered by a lighter gage panel 29.

The hinge assembly 13 includes a hinge pin 31 which is nonrotationally fixed such as by welds 33 in the corners of the door 11 formed by the frame 15 and the flanges 17 and 21 at the top and 19 and 21 at the bottom.

The hinge assembly 13 also includes a hinge housing 35 which clamps against the hinge pin 31 yet permits relative rotation between the hinge pin and the housing. The hinge housing 35 includes a first or angle member 37 and a second or clamp member 39. The angle member 37 has first 41 and second 43 elongated, substantially perpendicular angle flanges joined along a common edge 45 forming an internal corner 47. A mounting flange 49 extends substantially perpendicular to the first flange 41 so that the angle member 37 is generally U-shaped.

The clamp member 39 has a flat, elongated body 51 with first and second clamping flanges 53 projecting laterally from opposite ends of the elongated body 51 in spaced parallel relation. These clamping flanges 53 form external corners 55 with aligned corner recesses 57. Integral clamping tabs 59 extend from the clamping tabs 53 adjacent the corner recesses 57 and are provided with apertures 61. The elongated body 51, the clamping flanges 53 and the clamping tabs 59 are in mutually orthogonal planes.

The clamp member 39 mates with the angle member 37 so that the fixed hinge pin 31 is clamped into the internal corner 47 of the angle member 37 by the corner recesses 57 in the clamping flanges 53 as best seen in FIG. 3. The corner recess 57 is an open circle which is tangent to one edge 63 of the clamping flanges and to the outer surface 65 of the clamping tabs 59. The radius R.sub.1 of the corner recess 57 is slightly shorter than the radius R.sub.2 of the fixed hinge pin 31. In the exemplary embodiment of the invention, the radius R.sub.1 is 0.123 inches and the radius R.sub.2 is 0.125 inches. This creates a compression fit between the hinge assembly 13 and the fixed hinge pin 31 at spaced apart points adjacent the top and the bottom of the hinge pin 31 which securely fixes the hinge pin axis but allows rotation of the hinge pin relative to the angle member 37 and clamp member 39.

The clamp member 39 is firmly secured to the angle member 37 by rivets 67 extending through the apertures 61 in the clamping tabs 59. In addition, the elongated body 51 of the clamp member is firmly secured against the mounting flange 49 of the angle member 37 by mounting rivets 69 which extend through mounting holes 71 in the mounting flange 49 and 73 in the elongated body 51 and attach the hinge assembly 13, and therefore the door 11, to an upright 75 forming a door jam on the cabinet 3. The orthogonal orientation of the elongated body 51, clamping flanges 53 and clamping tabs 59 of the clamp member 39 and the close proximity of the clamping tabs 59 to the corner recesses 57 in which the hinge pin 31 is retained, assure a good compression fit of the hinge assembly on the hinge pin 31.

While in the exemplary embodiment of the invention the hinge pin 31 is nonrotationally fixed on the door 11, and the hinge housing is fixed to the door jam, it should be understood that the hinge pin could be nonrotationally fixed to the door jam and the hinge housing could be mounted on the door.

It will be noted that the hinge housing extends through the slot 25 in the door frame 15 and end flange 21, and that with the door closed the outer surface of the flange 41 on the angle member 37 is flush with the outer surface of the door, while the outer surface of the second flange 43 is flush with the flange 21.

While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.