Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
HOUSING FOR FLOAT SWITCH MECHANISM
This invention relates generally to float mocha-
nisms of the type intended to be carried in an aperture
wall of a liquid-containing tank or vessel/ and more
particularly to mechanisms of the kind incorporating a
movable float carrying an electrical contact which is
engage able with an inner wall surface of the float house
in in response to changes in the level of the liquid
being monitored or gauged.
Such devices incorporate a tubular threaded body
which constitutes a mounting for the mechanism, and a
cylindrical casing or housing in which a float is car-
fled. The float has one electrical contact that engages
the inner surface of the casing wall in response to a
fall in the liquid level, and another contact that en-
gages an insulatedly mounted, conductive cup of the body
portion. Electrical continuity to ground is thus stab-
fished from the casing to the cup The latter is in
turn connected to a connector receptacle, and the come
pletion of the ground circuit is employed to operate a
warning light or other indicator, so as to alert the
driver or other person that the level of liquid had fat-
ion below a pro determined point.
The casing of one particular prior device was con-
stituted as a drawn sheet-metal shell, and had openings
in its side and end walls which were punched out follow-
in a drawing procedure. While the operation of this
prior device has been found to be satisfactory, the use
of drawn metal parts necessitated successive punching
operations that constituted a significant expense, due
to the labor involved with the multiple fabricating
-- 1 --
steps. In addition, plating of the completed pieces, if
required, usually was undertaken as a separate process
following completion of the formation of the casing.
The above disadvantages of prior float mechanisms
are largely obviated by the present invention which pro-
vises, in a float switch mechanism ox the type having a
tubular body portion by which the mechanism can be mount-
Ed in an aperture of a tank or vessel, and having an
electrically conductive housing connected to the body
portion and a float which is held captive in the housing
and movable therein, and wherein the gloat carries an
electrical contact for engagement with an inner wall of
the housing in response to changes in the level of it-
quid in the vessel, the improvement comprising said float
housing being in the form of a one-piece sheet-metal
casing formed into a cylindrical shape f rum a metal stamp-
in, said casing having an elongate axis and having par-
allot to its axis a pair of adjoining longitudinal edge
portions one of which has a lateral offset to enable it
to overlap the other, means defining an aperture in said
casing adjacent that one of the edge portions which has
the said offset, and said casing having a tab on the
other of said edge portions extending radially outward
through said aperture and bending back upon said one
edge portion so as to securely retain said edge portions
against separation, said aperture edge portion being
sandwiched between the said other edge portion and said
tab, and abutment means disposed at one end of said gas-
in and extending at least partially across said end so
as to engage and hold the float captive in said casing.
-- 2
I
The invention further provides in a float switch
mechanism of the type having a tubular body portion by
which the mechanism can be mounted in an aperture of a
tank or vessel, and having an electrically conductive
housing connected to the body portion and a float which
is held captive in the housing and movable therein, and
wherein the float carries an electrical contact for en-
gagement with an inner wall of the housing in response
to changes in the level of liquid in the vessel, the
improvement comprising said float housing being in the
form of a one-piece sheet-metal casing formed into a
cylindrical shape from a metal stamping said casing
having an elongate axis and having parallel to its axis
a pair of adjoining longitudinal edge portions which
engage one another in abutting relation, means on one of
said edge portions defining a reentrant configuration,
means on the other of said edge portions defining a eon-
responding reentrant slot configuration, said reentrant
configuration being received in said no entrant slot
configuration so as to maintain said edge portions jut-
topside, and abutment means disposed at one end of said
casing and extending at least partially across said end
so as to engage and hold the float captive in said gas-
in.
The invention further provides the method of making
a casing for a float mechanism of the type having a move
able float carrying an electrical contact disposed with-
in the casing and engage able with an inner surface there-
of, said casing being electrically conductive comprise
in the steps of stamping out of sheet metal material generally rectangular blank having a tab along one of
its edges and an aperture along the opposite edge, and a
projection along a third edge, worming said blank into a
cylinder and passing said tab through said aperture
bending said tab back into firm engagement with an outer
surface of the said opposite edge such that it securely
retains said one edge and said opposite edge against
separation, and bending said projection radially inward
until it is generally perpendicular to the axis of the
cylinder so as to form an abutment for holding captive
the said float.
Other features and advantages will hereinafter apt
pear.
In the drawings:
Figure 1 is an enlarged side elevation Al view, par-
lye broken away, of the float switch mechanism, portico-
laxly illustrating a float casing constituted of sheet
metal bent into a cylinder and with its edge portions
juxtaposed, and illustrating a tab on one edge portion
passing through an aperture in the other edge portion
and being bent back over the latter, so as to retain the
edge portions against separation.
Fig. 2 is a right end elevation of the casing of
the mechanism, still further enlarged and illustrating
the multiple abutments or lugs integral therewith and
extending across the casing end, for holding the float
captive.
Fig. 3 is a top plan view, enlarged t of a metal
stamping in its flat condition, from which the casing of
Figs. 1 and 2 is formed.
Fig. 4 it an edge view of the stamping of Fig. 3.
I
Fig. 5 is a fragmentary section taken on the line
5--5 of Fig. 2.
Fig. 6 is a fragmentary view like Fig. 1, of a mod-
flied casing, showing abutting edge portions of the gas-
in provided with interlocking configurations that retain
the edge portions against separation.
Fig. 7 is a view similar to Fig. 3, of the flat
metal stamping employed to form the modified casing con-
struction of Fig. 6.
Fig. 8 is an edge view of the blank of Fig. 7, and
Fig. 9 is a right end elevation, further enlarged,
of the casing of Fig. 6.
Referring first to Fig 1 there is illustrated a
float-type monitor device for installation in the wall
10 of a tank or vessel containing liquid (not shown)
whose level is to be monitored, tube wall 10 lying gent
orally in a vertical plane The monitor device comprise
en a fitting 12 having brazed thereto a flange or abut-
mint plate 14, and having a threaded barrel 16. The bar-
net 16 is secured in the wall 10 by a nut 18. Alternate-
lye the wall 10 can be tapped and the barrel merely
screwed in position, in which case the nut would be omit-
ted.
The fitting 12 is hollow, and has a cup-like elect
tribal contact 20 and a male terminal 22 connected there-
with, held in position by an insulating bushing (not
shown). The fitting 12 has a transverse slot 24 to no-
chive a spring clip 25 as shown which prevents inadver-
tent dislodgement of a female connector (also not shown)
that can be plugged into the fitting.
-- 5 --
The exterior of the barrel 16 has an annular groove
26 in which there is crimped one end of a tubular metal
casing 28. The casing 28 has top, bottom and side open-
ins 30, and an end opening 32 to enable fluid from the
containing vessel to enter the interior of the casing
when the level rises.
Disposed within the casing 28 is an elongate float
generally designated 34, having an embedded contact strip
36 extending for substantially the entire axial length
thereof, with opposite ends 38, 40 protruding therefrom.
The end 38 is preferably in the form of a single pointed
tip which can engage the inner surface of the cup 2Q
when the float level falls. The opposite end is intended
to engage the inner surface of the casing 28. Such en-
gagement thus grounds the cup 20 and associated terminal
22 to the wall 10, through the contact strip 36 when the
liquid level is low. The grounding of terminal 22 can
activate a warning light, or initiate another type of
indication provided for the operator of the vehicle.
Referring now to Figs. 3 and 4, the casing 28 is
formed from a one-piece sheet metal blank designated 42,
which is preferably but not necessarily replated The
blank can be formed in a suitable punch (not shown),
with the general outline as illustrated, and having four
elongate axially aligned apertures 30. The blank 42 has
a pair of opposite longitudinal edge portions 44, 46,
the portion 44 having a tab 48 and portion 46 having an
offset 50 joined to other parts of the blank by a bend
or shoulder 52 of Z-shaped cross section. Disposed along
the third edge portion 54 ox the blank is a series of
lugs 56 having dimpled formations 58 whose function will
6 --
;~28~
be described below. The -tab 48 can have a bend imparted
to it, as at 60, at the same time that the punching is
accomplished.
Further, the blank 42 is bent into a generally cry-
lindrical shape with the edge portion 44 underlying and
fitting against the offset 50, as shown in Figs. 1 and
2, and the tab 48 passed through the lowermost aperture
30 in Fig. 3 and bent back so as to overlie the offset
50 and firmly retain the edge portions 44, 46 against
separation. This can be accomplished either manually, or
by automatic machinery (not shown). The provision of the
offset 50 thus eliminates inwardly extending protrusions
at the location of the seam 62 in Fig. 2, and there is
thus a relatively smooth transition between the junta-
posed edge portions 44 and 46. The adjacent inner sun-
faces 64 and 66 of the edge portions 44, 46 respectively
are thus maintained in alignment or flush with one an-
other, and are seen to lie in a single cylindrical sun-
face, with no inwardly extending protrusions which might
hinder smooth and uninterrupted movement of the float
34. In Fig. 2 it can be seen that the edge portion 46
(offset 50~ is sandwiched between the opposite edge port
lion 44 and the tab 48. The latter engages the outer
surface of the offset 50 when it is fully bent back.
The offset 50 and tab US also lie in cylindrical sun-
faces which are coaxial with the cylindrical surface
containing the edge portion 44.
Further, abutment means are provided at the open
end of the casing, in the form of one or more lugs 56
which are disposed generally perpendicular to the axis
of the casing and extend at least partially across the
-- 7 --
end so as to hold the float captive. Four lugs 56 are
shown in Fig. 2, but other configurations are possible.
As noted above, these lugs are formed during the initial
stamping operation, and the bend can be imparted to them
following the formation of the casing into the cylinder-
eel shape. Also, the lugs have circular or spherical
dimpled formations 58 which project slightly into the
interior of the casing, as in jigs. 1 and 5. These lung-
lion to prevent the end of the float 34 which is adjacent
the lugs 56 from engaging the flat portions of the lugs
and possibly sticking thereto by capillarityO That is,
the dimples 58 engage the end of the float first, if the
latter drifts toward the right in Fig. 1.
The above construction has the following important
advantages, as compared to the use of drawn sheet metal
cups, for use as casings. Where it is desired that the
finished component be plated, as is usually the case
with steel parts replated flat sheet metal stock can
be employed, and when the blanks 42 are formed initially,
the stock has already been plated. There is thus elm-
noted an additional step in the manufacturing operation,
namely that involved with plating a large number of cup-
like drawn shells. Although the edges of the blank are
constituted of at least partially exposed bare steel, we
have found that the stamping operation effects a pinch-
in of these edges, such that the plated opposite flat
surfaces tend to curl and close over these bare edges,
and minimize the exposure. The edges are thus mostly
protected, and it has been found that little degenera-
lion of the finished product occurs, even if the edges
-- 8 --
are left without further treatment in the form of no-
plating.
Secondly, the present construction is considerably
less expensive -to carry out from the manufacturing stand-
point. In particular the multiple steps involved in draw-
in a cup-like shell from a slat piece of material are
completely eliminated. The blanking and wrapping opera-
lions of the present arrangement can be readily carried
out, and the procedures lend themselves to mass product
lion techniques. As mentioned above, there is provided relatively smooth inner surface of cylindrical configure-
lion, even at the location of the seam 62. This is made
possible by the provision of the offset 50. The smooth
interior surface eliminates potential problems involving
interference with the movement of the float, etc., since
no inwardly extending protrusions are seen to exist.
A modification is illustrated in Figs. 6-9, show-
in a modified casing 68 carried on -the barrel 16 of the
float mechanism As in the previous construction, the
casing has elongate apertures 70 parallel to the casing
axis, and an end aperture 72. The casing 68 is formed
from a single flat piece of sheet-metal 74 shown in Fig.
7, which has been blanked out from a larger sheet (not
shown). The sheet 74 has opposite longitudinal edge port
lions 76, 78, and a series of tabs 80 along its third
edge portion 82. The tabs 80 have dimpled formations in
the form of surface protrusions 84. Fig. 8 illustrates
an edge view of the blank of Fig. 7.
The edge portion 78 has a series of dovetails or
dovetail projections 86 constituting a reentrant con-
figuration, and the opposite edge portion 76 has multi-
pie corresponding dovetail slots 88 also defining no-
entrant configurations. The casing 68 is formed by wrap-
ping the blank 74 around a suitable form (not shown)
into a cylindrical shape such that the dovetail project
lions 86 are received in the dovetail slots 88. This
maintains the edge portions 76, 78 juxtaposed, and no-
twins them against separation. Also, the lugs 80 are
formed to extend transversely across the far end of the
casing in Figs. 6 and 9. The lugs 80 hold captive the
float 34, and the dimples 84 prevent the end of the
float from engaging the broad inner surfaces of the lugs
80 and possibly sticking thereto by capillarity. In oh-
or respects the embodiment of Figs. 6-9 is similar to
the first embodiment, and accordingly further discussion
of the structure or operation need not be undertaken
The advantages of the embodiment of Fig. 6-9 are
essentially the same as those of the first embodiment,
namely that the use of pro plated stock reduces the numb
bier of steps involved with the fabrication of the device.
In addition, the stamping can be carried out quickly,
this being also true of the step involved with forming
the blank into a cylindrical shape. Overall fabrication
cost is thus considerably lower than would be the case
if drawing operations were required, together with plats
in steps following assembly.
There is also disclosed a novel method for making a
casing for a float mechanism of the type having a move
able float 34 carrying an electrical contact 40 disposed
within the casing and engage able with an inner surface
thereof, and wherein the casing is electrically conduct
live, the method including the steps of stamping out of
-- 10 --
sheet material a generally rectangular blank 42 having a
tab 48 along one of its edge portions 44, and having an
aperture 30 along the opposite edge portion 461 bending
the blank 42 into a cylinder and passing the tab 48
through the aperture 30, bending the tab back into firm
engagement with an outer surface of the edge portion 46
such that it securely retains the edge portions 44 and
46 against separation, and bending the projection 56
radially inward until it is generally perpendicular to
the axis of the casing, thereby forming an abutment which
holds the float 34 captive. The method further includes
the step of imparting an offset 50 to the edge portion
46, such that when the blank is formed into a cylinder,
the offset overlies the outer surface of the edge portion
44 so as to bring the inner surfaces 64 and 66 into align-
mint with one another, such that they lie within Essex-
tidally the same theoretical cylindrical surface.
Also, the method includes the additional step of
imparting a dimpled configuration 58 to the projection
56 for engagement by the float 34, such that there is
minimized the area of engagement of the projection 56
and float 34 if the latter drifts toward the projection.
The likelihood of the end of the float sticking to the
projection by capillarity is thus greatly reduced or
eliminated.
The arrangements that have been disclosed are thus
seen to be especially simple in construction and index-
pensive to manufacture, thereby reducing the overall
cost. They lend themselves to mass production techniques,
and with the use of replated stock, there can be elm-
inated costs involved with subsequent plating or Corey-
sion-resist type finishing operations. Accordingly there
is realized a cost reduction as comparec3 -to the use of
drawn sheet metal parts, where subsequent punching and
plating operations would likely be needed.
The devices are thus seen to represent a distinct
advance and improvement in this field.
Each and every one of the appended claims defines
an aspect of the invention which is distinct from all
others, and accordingly each claim is to be treated in
this manner when examined in the light of the prior art
devices in any determination of novelty or validity.
Variations and modifications are possible without
departing from the spirit of the claims.
- 12 -
