US 2895637 A
Description (OCR text may contain errors)
July 21, 1959 BAKKE ETAL 2,895,637
METER HOUSING Filed May 9, 1956 lnvenrors Hons A. Bukke Fig.8 if' g- Henry D. Treirel Their AHorney United t i METER HOUSING Application May 9, 1956, Serial No. 583,679 Claims. (Cl. 220-40) This invention relates generally to improvements in meter housings and in particular to improved bayonet locking arrangements therefor.
In the past, it has been common practice to construct meter housings as two-part assemblies comprising a base and a detachable cover. Suitable means were provided to securely hold the cover on the base and such means often comprised some form of bayonet lock to permit quick and easy removal or replacement of the cover, as desired. In the case of a housing for a watthour meter, it has been customary to provide a resilient gasket between the cover and the base to seal the interior of the housing against any dust or other foreign matter externally thereof. Such gaskets have also added a degree of flexibility to the locking arrangements to compensate for any minor variations in parts during manufacture, in that their resiliency could be utilized to establish the clamping pressure necessary for obtaining a tight fit between the cover and base.
As is well known, watthour meters are left unattended for long periods of time and it is desirable that the cover remain securely and tightly in place at all times when in use. It has been found that the gaskets utilized in the aforementioned housings lose some of their resiliency with age and will assume a set configuration that often reduces the clamping pressures enough to destroy the tight fit initially established.
Therefore, it is a primary object of the invention to provide improved bayonet locking arrangements for a meter housing that will at all times insure a tight fit between the cover and base thereof.
It is another object of the invention to provide such improved arrangements without significantly adding to the cost or complexity of the end product.
In one aspect of the invention, a base member is formed with an annular flange which serves as a seat for the annularly flanged end of an open-ended cover which cooperates with the base to form a meter housing. The peripheral edge of the base flange has a series of spaced notches to accommodate a corresponding series of inwardly projecting locking tabs spaced around the peripheral edge of the cover flange. When the tabs are aligned with the notches, the cover may be fitted onto the base, after which the cover is tightly secured in place by turning it relative to the base. The tabs grip the under side of the base flange to clamp the cover to the base and a resilient gasket inserted between the base and cover flanges is put under compression to insure an effective seal and a tight fit.
To compensate for the aging eflect of the gasket, the locking tabs are flexibly mounted on the cover and the arrangement is such that the tab supporting structure is elastically deformed during assembly of the housing.
Should the gasket change in resiliency during use, the
flexibly mounted tab will take up any looseness in the assembly to maintain a tight fit between the parts at all times.
tes Patnt ice The objects of the invention together with the benefits and advantages to be derived therefrom, will be more fully understood upon reference to the following detailed description of the invention, taken in conjuncfilm with the drawing annexed hereto, in which:
Figure l is a side view, in elevation, on a reduced scale, of a typical meter housing which embodies the subject invention, and;
Figure 2 is a bottom view of the meter housing shown in Figure l, on an enlarged scale, and;
Figure 3 is a perspective view of a portion of the housing shown in Figure 1, on an enlarged scale, and;
Figure 4 is an exploded diagram of the parts shown in Figure 3, on an enlarged scale, and;
Figure 5 is a view taken along lines 55 shown in Figure 2, on an enlarged scale, and;
Figure 6 is a view taken along lines 6--6 shown in Figure 2, on an enlarged scale, and;
Figure 7 is a top view of the flexibly mounted locking tab, and;
Figure 8 is an end view of the tab structure, showing the slight twist imparted thereto, and;
Figure 9 is an enlarged view of the tab itself, showing the slight curvature imparted thereto.
Referring first to Figure 1 there is shown on a reduced scale a typical two-part housing for a watthour meter comprising a base member 11 and a cover 12 mounted thereon. As is well known in the art, the base member may be molded from a suitable plastic material and the cover is formed of glass. In a watthour meter, the base member carries the meter mechanism and its associated terminals, and in the form shown, has a plurality of supporting feet 13 formed integrally therewith to facilitate handling of the meter during manufacture and installation thereof. As is shown in Figure 2, the base also has a plurality of slots 14 through which the terminals of the meter mechanism are adapted to project.
The base member is annnular in shape and its outer rim is in the form of a flange 15 best shown in Figures 5 and 6 and on this flange is mounted the flanged open end 16 of the cover. The flanged end 16 is provided with an annular shoulder 17 on which may be permanently affixed by suitable adhesive material or the like a resilient gasket 18.
Overlying the outer surfaces of the flanged end 16 is a flanged metallic ring 19 on which is flexibly mounted a locking tab 21, the details of which will be more fully described hereinafter. The tab 21 projects inwardly from the ring 19 and is formed proximate to the outer extremity of an elastically deformable elongated arcuate, metallic arm 22 adapted to be welded near its inner extremity to the inner surface of ring 19. Conventional spot welding techniques may be utilized to secure the arm 22 to the ring but of course it is to be understood that other techniques such as soldering or brazing could also be utilized if desired. In Figure 4 the spot welds are shown at 23.
The inner extremity of member 22 has a flanged portion 24 adapted to rest in a recess 25 provided in the outer edge of the flanged cover end 16.
In the assembly of the aforementioned parts the metal ring 19 is slipped over the glass cover and held thereon by the interaction of the flanged portions provided on both the ring and the cover. With the ring thus in place, the arm 22 is positioned firmly against the ring with its flanged extremity 24 resting in the recess 25. While so held, the parts are spot welded together and by such operation, it is apparent that not only is the part 22 securely afiixed to the ring 19, but the ring 19 is in turn securely affixed to the glass cover 12.
Referring to'Figures 2 and 4, it is seen that the base member has a plurality of notches 26 spaced around the periphery of its annular rim. These notches have adjacent thereto a plurality of cam sections 27 formed by cutting away a portion of the flange such that the cam sections gradually increase in thickness in a direction away from the associated notches.
It is apparent from the above that the notches 26 accommodate the tabs 21 to permit the cover to be fitted on the base and the cam sections 27 cooperate with the tabs 21 upon turning of the cover relative to the base to lock the cover tightly in place. Thus, it is apparent that the tabs 21 together with the notches 26 and cam sections 27 comprise a bayonet lock which enables the two-part housing to be readily assembled or disassembled as desired.
The inclined surface of the cam sections 27 permits a gradual increase in clamping forces and the clamping forces so developed compress the gasket 18 to insure a tight sealed fit between the cover and base.
Since the locking tab 21 is mounted at the outer extremity of the elastically deformable member 22, it is apparent that during assembly of the cover to the base, the member 22 will be deformed, the extent of deformation depending upon the dimensions and arrangements of the associated parts. Thus, upon assembly, the arm 22 will be deformed somewhat, but it will not be deformed beyond its elastic limit, so that it will always return to its initial position upon disassembly of the housing. Moreover, should there be any change in resiliency of the gasket 18 during use, which could cause the gasket to set and thus detract from the tightness of the fit between the cover and the base, the arm 22 will function to take up any looseness that develops in the housing so that the cover and base remain tightly fitted relative to each other at all times.
To prevent the member 22 from being deformed beyond its elastic limit, a stop member 28 is suitably aflixed to the ring 19 by spot welding or the like and this stop member has a flanged end 29 which cooperates with the outer tip 31 of the member 22 which extends beyond the locking tab 21. If by chance the combined manufacturing tolerances of the housing components exceed permissive limits, resulting in a tendencyupon assembly of the cover to the base for the members 22 to flex beyond their elastic limits, the outer tip 31 will come up against the lower edge of flange 29 and prevent such excessive flexure.
It is to be noted that fiexure or deformation of the member 22 will be mostly a typical pivotal bending action but it will also undergo some twisting about its major axis. To prevent the arm 22 from taking a permanent set while in use, thus reducing the effectiveness of its compensating action, it may be preformed prior to assembly with a slight twist about its major axis in the direction it would normally move during assembly of the cover to the base. Figures 7 and 8 clearly show the preformed twist and in the example shown it has been found that a 2 twist is suflicient to prevent any tendency of the mernber 22 to take a permanent set when in use.
The slight curvature given to tab 21, as is most clearly shown in Figure 9, is for the purpose of maintaining the pressure point between the base and the tab reasonably uniform even though there might be slight variations in the desired position of the flanged end 24 relative to the recess 25. That is, the curvature of the tab 21 compensates for any slight variations in manufacturing tolerances and makes it possible to weld the arm 22 at a fixed distance from the edge of the glass cover or the gasket surface to thereby assemble the ring 19 tightly in place on the cover 12.
In the illustrated embodiment, the arm 22 is formed of stainless steel to minimize any corrosion during use and functions quite adequately as a spring member, since the various cooperating parts have been designed to minimile the degree of flexing required to provide the necessary compensating action. For example, in the arrangement shown, it has been found that a total flexure of .030 inch at the tab end of member 22 is suflicient to provide the compensating action.
Therefore, while a particular embodiment of the subject invention has been shown and described herein, it is in the nature of description rather than limitation, and it will occur to those skilled in the art that various changes, modifications, and combinations may be made within the province of the appended claims, and without departing either in spirit or scope from this invention in its broader aspects.
What we claim as new and desire to secure by Letters Patent in the United States Patent Ofiice is:
l. A watthour meter housing comprising: a base member having an annular flange, said flange having a plurality of notches spaced around its peripheral edge; a detachable cover having an outwardly flanged annular open end adapted to fit on said base flange; an annular resilient sealing gasket mounted on said cover flange adapted to overlie said base flange; an annular flanged metallic ring mounted on said cover flange adapted to have its ring portion surround the outer edge portions of said base flange and said cover flange; and a plurality of elastically deformable metallic arms spaced around said metallic ring nd surrounded thereby, said arms being curved to conform to the curvature of said ring and situated contiguous thereto with their edges overlying said cover flange, each of said arms having one end securely fixed to said ring and having an inwardly projecting radial tab formed on its other end, there being a tab for each of said notches, said other ends being free to move a limited amount relative to said fixed ends, said tabs cooperating with said notches and portions of said base flange to form a bayonet lock for clamping said cover on said base, said arms being elastically deformed when said bayonet lock is formed to maintain continuous clamping pressure on said gasket, said deformation being suflicient to compensate for changes in resiliency of said gasket caused by aging effects.
2. The invention defined by claim 1 wherein said arms. have flanged portions at their fixed ends which bear upon recessed portions of said cover flange whereby said ring and said cover are locked securely together.
3. The invention defined by claim 1 wherein said base flange has inclined cam sections adjacent each notch, each of said cam sections increasing gradually in thickness away from its adjacent notch, and said tabs slidably engage said cam sections when said cover is mounted on said base, said tabs moving during mounting in the direction toward increasing cam section thickness.
4. The invention defined by claim 3 wherein each of said arms has an extension beyond its corresponding tab, and a plurality of inwardly projecting radial stop members overlie said extensions, said stop members being secured to said ring and cooperating with said extensions to limit the permissible elastic deformation of said arm.
5. The invention defined by claim 4 wherein said arm has its free end permanently twisted about its major axis in the direction it would normally move when said cover is positioned in said base member.
References Cited in the file of this patent UNITED STATES PATENTS 631,907 Schmalenback Aug. 29, 1899 1,046,263 Calkins Dec. 3, 1912 1,239,704 Lee et al Sept. 11, 1917 1,576,580 Ellis Mar. 16, 1926 1,932,044 Mylins Oct. 24, 1933 1,969,499 Bradshaw et al Aug. 7, 1934 2,229,435 Barnes Jan. 21, 1941