US2971670A - Lighting fixture - Google Patents

Description

Feb. 14, 1961 v D. c. MGCORMACK 2,971,670

LIGHTING FIXTURE Filed March 11, 1957 2 Sheets-Sheet 1 7 '25 22 27 24 24a. Ha l7 l4 4 I2 ll K lNVENTOP DONALD C. M: CORMACK ATTORNEYS United States Patent LIGHTING FIXTURE Donald C. McCormack, Toronto, Ontario, Canada, as-

signorto J. A. Wilson Lighting & Display Limited, Toronto, Ontario, Canada, a corporation Filed Mar. 11, 1957, Ser. No. 645,185

3 Claims. (Cl..22038).

This invention relates to a lighting fixture, and is particularly concerned with means forconnecting upper and lower parts of a recessed lighting fixture.

Most indoor lighting fixtures for use overhead consist of an upper part which support a lamp and which also supports a lower part that provides a light diffuser. It is desirable to provide means for securely connecting the upper and lower parts while permitting quick and easy removal of the lower part for maintenance. It is also desirable to have the connecting means out of sight when the lower part is in place. 1

One object of this invention is to provide a fixture having these desirable features.

Another object is to provide an improved spring-loaded fixture connection in which the spring is normally subject to very low stress.

Another object is to provide a connection that is particularly well suited for fixtures in which the upper part is recessed in a ceiling.

Another important object is to provide connecting devices that can be used with fixtures having lower parts of various shapes.

Other objects and features of the invention will become apparent from the following description of a preferred embodiment that is illustrated in the accompanying drawings. In the drawings:

Fig. 1 is a perspective view looking up at a fixture mounted in a ceiling, with the lower part of the'fixture pulled down and swung to one side for access to the interior of the fixture;

Fig. 2 is a vertical sectional view through the fixture of Fig. 1, with the lower part in its normal upper position;

Fig. 3 is a fragmentary side view showing the operationof the connecting devices as the lower part is being pulled downwardly from the position of Fig. 2; and

Fig. 4 is a similar view showing one of the connecting devices when the lower part of the fixture has been moved farther down and is manually supported from below.

The fixture shown in the drawings has an upper part.

or housing 1 formed of metal and having a cylindrical side wall 2, an upwardly dished top 3, and an open lower end surrounded by an outwardly extending flange 4. It has in its wall'2 a plurality of vertical slots 5, and screws 6-extend through the slots and into L-shaped metal brackets 7 outside the housing. The housing fits in a circular hole in a ceiling 8 with the flange 4 against the underside of the ceiling, the brackets 7 being tightened down against the upper surface of the ceiling by means of the screws 6. A socket 9 for an incandescent lamp (not shown) is mounted in the housing, the dished portion 3' providing space for the lamp in the top of the housing.

The lower part or bottom of the fixture consists of a die cast circular metal rim'lil and a lens or globe 11 held thereby for transmitting light from the lamp. The rim. has an outer flange 12 adapted to engagethe underside of the ceiling and. conceal the flange 4, an

ice

upwardly extending web 13 (Fig. 1) adapted to fit within the wall 2, and an inner flange 14 for supporting the globe 11, the globe having an outwardly extending flange 11a that rests on the flange 14. At opposite sides of the rim are a pair of upwardly extending lugs 15 integral with the rim and having tapped holes for receiving screws 16. The screws 16 pass through vertical slots 17a in L-shaped metal brackets 17, which are fixed by the screws to clamp the flange 11a of the globe against the flange 14.

A pair of connecting devices generally indicated by reference numeral 18 are provided at opposite sides of the lower part of the fixture for suspending the lower part in its normal upper position shown in Fig. 2 or in its lowered position shown in Fig. 1. Each of the devices consist of a pivoted metal arm 19, a coil spring 20, and flat portions 21, 22, .the flat portion 21 being part of the rim web 13, and the similar portion 22 being spaced inwardly from the portion 21. A projection 23 extends upwardly as part of the portion 22. The arm 19 pivots in a slot 24 between the portions 21, 22, and near one end of the slot 24, a pivot pin 25 extends across the slot between the portions 21, 22 and provides the pivotal mounting for the arm 19. As shown in dotted lines in Figs. 2, 3 and 4, the other end of the slot is closed by an abutment 24:: which limits pivotal movement of the arm 19 in one direction. The spring 20 urges the arm 19 towards the abutment 24a, being connected to one of the points 29a, 20b, 26c on the arm 19, and to a point 20d on the web 13 on the. opposite side of abutment 24a from the pivot 25. The points 20a, 20b, 200 are successively farther from the point 2ild, and provide for some adjustment of the tension on the spring 20.

Each arm 19 has a slot 26 that extends generally upwardly from a closed lower end 26a (Fig. 4) adjacent the pivot 25 to a closed upper end 26b. Each slot 26 receives a pin 27 that is fast with the housing 1 near the lower end of the housing, the pins 27 protruding horizontally inwardly from opposite sides of the housing. The diameter of the pins is only slightly less than the width of the slots, the difierence being sufiicient however to allow the arms 19 to slide upwardly and downwardly on the pins. Each pin 27 has a head 27a that normally prevents the arm 19 from disengaging the pin, but each slot 26 has, below its upper end 26b, an enlargement 26c through which the head of the pin can pass. It will be convenient to refer to the lower portion of the slot as the lower end portion 26d, and to the upper portion as the upper end portion 26e.

The device 18 are identical, and they operate together in the same way, so that a consideration of the one shown in Figs. 2, 3 and 4 should suffice to explain the operation of both. In the normal position of the lower part of the fixture, shown in Fig. 2, the pin 27 is in the lower end portion 26d of the slot 26, and fits snugly in U- shaped recesses 21a, 22a in the fiat rim portions 21, 22. When the pin 27 is in the lower end portion of the slot as shown in Figure 2, the pin 27 is spaced from the pivot 25 and out of vertical alignment with the pivot 25. With the arm 19 held against the abutment 24a, as shown in Fig. 4, the bottoms of the recesses2'1a, 22a do not register with the lower portion 26 of the edge of the slot 26, but are slightly above it, and there is not quite room for the pin 27 in the opening between the bottoms of the recesses 21a, 22a and the upper portion 26g of the slot edge, and consequently in the condition shown in Fig. 2 the pin, due to its diameter, must hold the arm 19 slightly clear of the abutment 24a, ensuring that there is slight tension in the spring 2%} and that the bottoms of the recesses 21a, 22a are brought right up against the pin so that the lower part of the fixture is in exactly the right position relative to the upper part. The pin is confined in the lower end portion 26d of the slot 26 by.

the projection 23, which obstructs the lower end portion of the slot. The edge portion 26g of the slot extends over the pin 27 in contact therewith, and half the weight o'fthejlowe'r part'ofthe fixtureTis thus applied downwardly on the pin 27 by the edge portion26g of the arm 19. Since the pin 27 is out of vertical alignment with the pivot 25, the upward reactionof the pin against the edge portion 26g tends to pivot the arm 19 further away from the abutment 24a against the force of the spring 20. However, since the lower end portion 26d of the slot 26 is adjacent the pivot 25, the lever arm of this upward reaction about the pivot 25 is much shorter than the lever arm afiorded to the spring from'the more distant point 20a, 2% or 200. Consequently very slight spring tension is required to hold the lower part of the fixture inthe normal position shown in Fig. 2 when the only downward force on the lower part is its own weight. Thus, the spring 20 can be practically unstressed in the normal closed condition of the fixture.

The projection 23 has a camming edge consisting of a lower generally vertical portion 23a and an upper inclined portion 235. Under the force of the spring 20, the edge portion 23a and the slot edge portion 26g exert scissors-like forces which clamp the pin in the lower end portion of the slot 26 and in the recesses 21a, 22a.

However if one wishes to move the lower part of the fixture downwardly from the normal position of Fig. 2, he need only grasp opposite sides of the rim and pull downwardly. The additional reaction exerted by the pins 27 to this downward pull will force the edge portion 26g away from the edge portion 23a under the camming action of the latter on the pin, the arm 19 thus pivoting against the force of the spring 20 so that the projection 23 no longer obstructs the lower end portion 26d of the slot and the lower part of the fixture can move downwardly, as shown in Fig. 3.

The slot 26 extends from its lower end 26:: away from the pivot 25 so that the distance of the pivot, and hence of the lower part of the fixture, from the pin 27 can increase as the distance of the pin from the lower end of the slot increases. The generally vertical edge portion 23a of the projection 23 ensures that during the initial movement of the lower part of the fixture from its normal position the direction of movement is vertical. While the slot'26 extends generally upwardly, it will be noted from Fig. 2 that the lower end portion 26d of the slot is normally inclined from the vertical, and the amount of this inclination determines the amount that the spring 20 must be stretched to bring the lower end portion 26d to the substantially vertical position of Fig. 3 and allow movement of the lower part of the fixture downwardly. In the arrangement shown in the drawings, the lower end portion 26d of the slot is normally inclined approximately forty-five degrees to the vertical,

and as shown by Fig. 3 only a very slight downward movement of the lower part of the fixture requires considerable elongation of the spring 20. Thus, while the spring 20 can, in the position of Fig. 2, be relatively unstressed, a strong downward force is required for slight displacement of the lower part of the fixture, and consequently the fixture does not rattle or become accidentally dislodged.

Just below the position of Fig. 3 the camming edge portion 23b and slot edge portion 26g exert scissors-like forces on the pin 27 that assist the downward movement of the lower part of the fixture until the lower part has been lowered sufiiciently for the projection 23 to be out of contact with the pin, as shown for example in Fig. 4 where the pin is carrying no weight and the lower part of the fixture is being supported manually from below. The lower part can now be lowered further until the pin 27 is at the upper end 26b of the slot.

When the lower part of the fixture is horizontal, as in Fig. 2, the centre of gravity of the lower part preferably lies in a vertical plane passing through the recesses 21a,

22a, so that there is no tendency for one side of the lower part to sag relative to the other. The inclination of the slots 26 is such that the upper ends 26b of the slots do not lie in this vertical plane, and accordingly, when the lower part is suspended on the pins 27 at the upper ends of the slots, the lower part of the fixture swings to one side on the pins, as shown in Fig. 1, to tilt the lower part relative to the horizontal ceiling. Therefore, a workman who wishes to have. access to the interior of the fixture need not, after pullingthe lower part down, either support the lower part or push it to one side out of 'his way. If desired, however, he may completely remove the lower part by lifting it until the slot enlargements 26c are opposite the heads 27a of the pins, and by then pressing inwardly on the arms 19, which are of resilient metal, he can deflect the arms until the heads 27a pass through the enlargements 26c and the pins are no longer in the slots 26.

The lower part of the fixture can similarly be replaced on the pins by pressing the arms inwardly until the heads 27a snap through the enlargements 26c. There is no wrong way of attaching the upper and lower parts in view of the fact that the pins 27 lie in a vertical plane passing through the center line of the fixture.

With the lower part ofthe fixture in the position shown in Fig. 1, the torque to be overcome by each spring 20 is that due to one-half the weight of the lower part of the fixture acting vertically at a pin 27. The lever arm of this latter force about the pivot 25 is much shorter than that of the spring, since a vertical line through the pin does not pass far from the pivot. Thus, the spring is again subjected to only a low stress, and the arm 19 occupies a slot obstructed position.

The lower part of the fixture can be raised from its lowered position of Fig. 1 to its upper position'of Fig. 2 simply by pushing upwardly on the lower part, causing the pins 27 to engage the inclined camming edge portions 23b. These edge portions are inclined to the direction of the upper end portions 262 of the slots 26, and against the scissors-like action of the edge portions 23b and 26g the pins can push the arms 19 to one side, stretching the springs 20 until the projections 23 do not obstruct the slots, as shown in Fig. 3. Further upward force on the lower part of the fixture enables the springs 20 to slam the lower part home to the position of Fig. 2.

With the fixture in its normal closed condition (Fig. 2) a trim appearance is achieved, the supporting mechanism being completelyconcealed. The lower part is very securely'held in its upper position, and does not rattle, and yet the springs 20 are normally practically unstressed. The interior of the fixture is accessible simply by pulling down onthe rim, and there are no knobs or screws to handle. The lower part can support itself from the pins 27 in its lowered position, or it can be completely removed.

Sometimes it may be necessary to use the fixture of this invention in a location where the ceiling is not level, or, where due to some peculiarity in the ceiling or in the opening cut in it the flange 4 is not flush against the lower surface of the ceiling but is raised somewhat from the position of Fig. 2. These variations can be accommodateddu'e to the fact that the lower end portion 26d of the slot 26 is normally inclined to the vertical and has some length. Even if, due to some irregularity, the lower part cannot be raised high enough for the pin 27 to be located snugly in the recesses 21a, 2211 against the end of the slot 26a, as long as the pin can be located in the slot at some position almost up to that shown in Fig. 3 the lower part of the fixture will be held securely to the upper part and the rim 10 will bear against the ceiling. Of course, the advantage of having the spring 20 normally practically unstressed will be lost, but nevertheless the fixture can be successfully used. Thus, use of the fixture is not absolutely dependent upon having the ideal ceiling condition shown in Fig. 2.

It will be understood that the construction shown in the drawings is by way of example only, and that many modifications can be made, It would be possible, for example, to provide the slots 26 in arms fast with the rim 10, and to make the projections 23 slidable or pivotahle to and from slot obstructing positions. Also the pins 27 could be provided on the lower part of the fixture, and the arms 19, portions 21, 22 and projections 23 on the upper part. The connecting devices 18 can be used with rims of almost any shape; obviously, for example, if the upper and lower parts of the fixture were square, in plan, rather than circular, the connecting devices 18 would operate equally well. The invention may of course be applied to fixtures that are not recessed in a ceiling. These, and other modifications and variations that will occur to those skilled in the art, are therefore intended to fall within the scope of the following claims.

What I claim as my invention is:

1. A lighting fixture comprising an u per housing having an open lower end, a pin protruding inwardly from one side of the housing and a similar pin protruding inwardly from the opposite side, a bottom for the housing including a light-transmitting part, and a pair of devices at opposite sides of said bottom for supporting said bottom on the pins in a normal upper position and in a lowered position, each of the devices comprising an arm, a pivot for the arm on said bottom, the arm having a slot extending generally upwardly and having a closed lower end portion adjacent the pivot and a closed upper end, the slot being adapted to receive one of the pins of the housing, the location of the pin in the slot varying from the lower end portion of the slot to the upper end as said bottom is moved from its normal upper position to its lowered position, a projection on said bottom adapted to obstruct the lower end portion of the slot, the arm being pivotable between a normal position where the lower end portion of the slot is obstructed by the projection and another position where the slot is sub stantially unobstructed by the projection, a coil spring connected between a point on said bottom and a point on said arm that is farther from the pivot than the lower end portion of the slot, the spring normally holding the arm in its said normal position when the pin is in the lower end portion of the slot, the projection having a camming edge engaged by the pin when said bottom is being moved between its said positions to pivot the arm to said other position against the force of the spring.

2. A lighting fixture as claimed in claim 1, wherein the arm has a slot edge, the slot edge and camming edge, under the force of the spring on the arm, being adapted to exert scissors-like forces on the pin when said bottom is being moved between its said positions, said scissors-like forces clamping the pin in the lower end portion of the slot when said bottom is in its normal upper position.

3. A lighting fixture as claimed in claim 2, wherein said bottom has portions adapted to lie in a horizontal plane when the pins are clamped in the lower end portions of the slots, said bottom when the pins are in the upper ends of the slots being swingable on the pins, the upper ends of the slots being so located relative to the centre of gravity of said bottom that with the pins in the upper ends of the slots the bottom under the force of gravity swings on the pins to tilt said portions relative to a horizontal plane.

References Cited in the file of this patent UNITED STATES PATENTS 1,144,159 Trauxall June 22, 1915 2,252,653 Thomas Aug. 12, 1941 2,550,008 Freeman Apr. 24, 1951 2,636,978 Williamson Apr. 28, 1953 2,639,368 Pryne May 19, 1953

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