Note: Descriptions are shown in the official language in which they were submitted.
I
~;DJUSTABLE-GRIP LATCH
The present invention relates generally to an
adjustable-grip latch for risibly securing closures of
industrial cabinets and the like. Morn particularly, the
present invention relates to an adjustable-yrip latch having a
shippable, friction type drive connection formed between an
operating shaft and a Pablo
Ad~ustable-grip latches of a variety of configurations
have been proposed for releasable securing industrial cabinet
closures and the like. Such latches are particularly useful
where it is desired (l) to compress a gasket which engages
perimetrically-extending portions of a closure when the closure
has been closed, or 12) to suppress vibration of a closure by
clamping it snugly into engagement with such framework as
defines the opening that is closed by the closure, or (3) to
provide a tightly closing latch which will compensate for
irregularities in manufacturing tolerances or for changes in
dimensions due to wear.
Prior proposals for tool-engageable operating heads
for adjustable grip latches and the like are disclosed in U. S.
Patent 4,369,678 and in U. S. Design Patents 270,229, 270,424,
and 270,707.
One type of adjustable-grip latch which has been
proposed includes a mounting ferrule a shaft, a knob, a stop, a
paw, and a compression coil spring. A central portion of the
shaft extends through and is journal Ed by the mounting ferrule.
A forward end portion of the shaft carries the kook. A rearward
end portion of the shaft is threaded into a threaded hole formed
in the pull The stop extends alongside the rearward end
portions of the shaft to limit the range of travel through which
the paw can move in response to rotation of the shaft. The
compression coil spring is carried on the shaft, with one end of
the spring engaging the paw, and the other end engaging the
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mounting ferrule. The paw and the stop are configured such
that only a one-fourth turn of the shaft is needed to move the
paw between its latched and unlatched positions. The
compression coil spring provides a shippable, friction-type
drive connection for transmitting only a limited amount of
torque prom the shaft to the paw, thereby enabling the shaft to
move the paw between its latched and unlatched positions, and
enabling the shaft to rotate relative to the paw when the paw
has engaged the stop.
The use of a compression coil spring to establish a
shippable, drive connection between a paw and a shaft in an
adjustable-grip lock has a number of drawbacks. As the shaft is
rotated relative to the paw to move the paw axially along the
shaft, the degree to which the spring is compressed changes as
the position of the paw along the shaft is changed. One of the
results of the change in spring compression is that the force
required to turn the shaft increases with an increase in
compression of the spring, and decreases as spring compression
is relieved. Another result is that the torque which is
transmitted from the shaft to the paw during rotation of the
shaft also varies. If the lengthy coil of wire which forms the
spring should break at any point along its length, or if the
open and exposed coils of the spring should become distorted, it
is possible for the driving connection between the paw and the
shaft to fail, whereby neither latching or unlatching operations
can be effected by rotating the shaft. Inasmuch as compression
coil springs are relatively large in size, adjustable-grip
latches which utilize compression coil springs are often found
to require undesirably large mounting spaces.
The present invention overcomes the foregoing and
other drawbacks of prior proposals by providing a latch which
utilizes a wave spring washer to provide a shippable,
Jo
friction-type drive connection between a paw and a shaft which
carries the paw.
An important feature of the invention lies in the
utilization of a wave spring washer to provide a shippable,
friction-type drive connection between an operating shaft and a
paw. The wave spring washer is employed in such a way that its
compression does not vary depending on the position of the paw
along the shaft. Inasmuch as the degree to which the wave
spring washer is compressed does not vary during operation of
the latch, neither the force required to turn the shaft, nor the
amount ox torque transmitted from the shaft to the paw vary
with changes in the position of the paw along the shaft.
A feature of the invention lies in the significantly
smaller design size which can be achieved where a thin,
disc-like wave spring washer is utilized instead of the
conventionally used compression coil spring In the preferred
practice of the invention, a further feature lies in the
provision of a paw with a housing structure which protectively
encloses the spring washer to assure that it will not be
accidentally deformed during installation or use of the latch.
A latch embodying the preferred practice of the
resent invention includes a mounting device such as a ferrule,
an operating shaft which is journal Ed by the ferrule, and a paw
which is carried on the shaft. A stop extends alongside the
shaft for limiting the range of movement of the paw between
latched and unlatched positions. A shippable, friction-type
drive connection utilizing a wave spring washer limits the
amount of torque that can be transmitted from the shaft to the
paw. The wave spring washer extends about the shaft and has
opposed, axially-spaced face portions which may be compressed
relatively axially in opposition to the spring action of the
washer. The drive connection also includes structure which
defines a pair of opposed surfaces which compressively engage
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the opposed face portions of the wave spring washer for
transmitting torque from the shaft through the washer to the
paw.
These and other features and a fuller understanding of
the invention may be had by referring to the following
description and claims taken in conjunction with the
accompanying drawings, wherein:
FIGURE 1 is an exploded perspective view of one
embodiment of a latch which includes features of the present
invention;
FIGURE 2 is a top plan view of the latch of FIGURE 1
installed on a closure and engaging a frame structure, with
portions broken away;
FIGURE 3 is a front elevation Al view of the latch,
closure and frame structure of FIGURE I with the latch in its
latched position, and with portions of the closure and frame
broken away;
FIGURE 4 is a front elevation Al view similar to FIGURE
3 but with the latch in its unlatched position;
FIGURE 5 is a perspective view of an alternate form of
wave spring washer which may be employed in a latch which
embodies features of the present invention;
FIGURE 6 is an exploded perspective view of an
alternate embodiment of a latch which includes features of the
present invention; and,
FIGURE 7 is a top plan view of the latch of FIGURE 6
installed on a closure and engaging a frame structure, with
portions broken away.
Referring to FIGURES 1-4, one form of an adjust-
able-grip latch which embodies features of the present invention
is indicated generally by the numeral 10. The latch 10 is
mounted on a movable closure 12. A frame structure 14 carries a
resilient, compressible gasket 16 for engaging pyrometrically
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extending portions of the closure 12 when the closure 12 is
closed. The frame structure 14 has a rear wall 18 which may he
engaged and gripped by the latch 10 to securely hold the closure
12 in its closed position. A mounting hole 20 is formed through
the closure 12. Portions of the latch 10 extend through the
hole 20, as will be explained. A pair of flat surface portions
one of which is indicated by the numeral 22 in FIGURE 1, define
opposite sides of the hole 20~
The principal components of the latch 10 include a
mounting ferrule 30, a stop 32, an operating shaft 34, a paw
36, a drive washer 38 and a wave sprint washer 40. The washers
38, 40 cooperate to establish a shippable, friction- type drive
connection between the shaft 34 and the paw 36.
The mounting ferrule 30 has a relatively large
diameter head 42, a threaded body 44, and a hole 46 which
extends coccal through the head 42 and the body 44 to define
an axis of rotation for the shaft 34. A pair of flats 48 are
formed on opposite sides of the body 44 for engaging the flat
surface portions 22 which define opposite sides of the mounting
hole 20 to prevent the ferrule 30 from turning in the mounting
hole 20. A shoulder 49 is provided at the juncture of the head
and body portions 42, 44 of the ferrule 30. The shoulder 49
engages the front face of the closure 12.
The stop 32 is an L-shaped member having a base
portion 50 which engages the rear face of the closure 12, and a
projecting portion 52 which extends rearwardly with respect to
the closure 12. A mounting hole 54 is formed through the base
portion 50. A pair of flat surfaces 56 define opposite sides of
the hole 54. The threaded body 44 of the ferrule 30 extends
through the hole 54, and the flats 48 formed on the body 44
engage the flat surfaces 56 to prevent relative turning movement
between the stop 32 and the ferrule 30. A pair of stop surfaces
58, 60 are defined on opposite sides of the projecting portion
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52. A nut 62 is threaded onto the body 44 of the ferrule 30.
The nut 62 is tightened into engagement with the bate portion 50
of the stop 32 to secure the ferrule 30 and the stop 32 rigidly
in place on the closure 12.
The operating shaft 34 has an operating head 70 formed
on its forward end. A radially extending shoulder 72 forms a
transition between the operating head 70 and a cylindrical
mounting portion 74. The mounting portion 74 extends through
the hole 46 in the ferrule 30~ and is journal Ed by the ferrule
30 for rotation. A circumfexentially- extending groove 76 is
formed in the mounting portion 74, and a crescent-shaped
retaining ring 78 is seated in the groove 76. The retaining
ring 78 engages the back of the ferrule 30, and the shoulder 72
engages the front of the ferrule 30, whereby the shaft 34 is
retained in place with respect to the ferrule 30.
The operating shaft 34 has a rearwardly extending
portion 80 which is threaded. A pair of flat drive surfaces 82
are formed on opposite sides of the threaded portion 80. A
circumferential extending groove 84 is formed near the rear
end of the shaft 34. A resilient retaining clip 86 is seated in
the groove 84.
The paw 36 has a central portion 90. A threaded hole
92 is formed through the central portion 90. The threaded
portion 80 of the shaft 34 is threaded into the hole 92 to mount
the paw 36 on the shaft 34.
The paw 36 has projecting arms 94, 96 which extend in
opposite directions from the central portion 90. The arm 94
defines a stop surface 98. The arm 96 is of dog- legged
configuration, and defines a stop surface 99 and a tapered tip
100. The paw 36 is in its latched position when the tip 100
overlies the rear wall 18 of the frame structure 14, as is shown
in FIGURES 2 and 3. The paw 36 is in its unlatched position
when the tip 100 is rotated to the position shown in FIGURE 4
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I 3~35
wherein the tip 100 in no way obstructs opening of the closure
12. When the paw 36 is in its latched position, its stop
surface 98 engages the stop surface 58 formed on the stop 32.
When the paw 36 is in its unlatched position, its stop surface
99 engages the stop surface 60. By this arrangement, the stop
surfaces 58, 60 98, 99 cooperate to limit the range of rotary
movement through which the paw 36 can travel.
The paw 36 has a housing 110 secured to it for
enclosing the washers 38, 40. The housing 110 has outer and
inner flange portions 112, 114 which are joined by an axially
extending shoulder 116. The outer flange 112 is spot welded at
spaced points 118 to the central portion 90. The inner flange
114 surrounds the shaft 34 and cooperates with the central
portion 90 to define a chamber within which the drive washer 38
and the wave spring washer 40 are housed.
The drive washer 38 has a hole 120 formed through it
to receive the shaft 34. A pair of flat surfaces 122 define
opposite sides of the hole 120 and drivingly engage the flat
drive surfaces 82 on the shaft 34. the drive washer 38 has an
outer diameter which lets it turn freely inside the shoulder 116
of the housing 110.
The wave spring washer 40 is a non-planar, axially-
compressible spring steel member of a commercially available
type. The washer 40 has a hole 124 formed through it to receive
the shaft 34, and has opposed face portions 126, 128 which can
be compressed axially toward each other. The washer 40 is of
the type sold by Associated Spring Corporation of Bristol,
Connecticut under the part number Wow- 008-5.
The housing 110 and the central portion 90 of the paw
36 cooperate to compressively sandwich the washers 38, 40 to
establish a shippable, friction-type drive connection between
the shaft 34 and the paw 36. In operation, when the shaft 34
is rotated counter-clockwise, as viewed in FIGURE 3, the
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frictiorl-drive connection transmits a sufficient amount of
torque to the paw 36 to rotate the paw 36 from its latched
position, as shown in FIGURE I to its unlatched position, as
shown in FIGURE 4. When the paw 36 reaches its unlatched
position, its stop surface 99 engages the stop 32. If the shaft
34 continues to rotate in a counter~cloclcwise direction, the
friction drive connectiorl slips, thereby permitting the threaded
portion 80 of the shaft 34 to thread out of the threaded hole 92
in the paw 36. As the shaft 34 threads out of the hole 92, the
paw 36 is caused to move rearwardly along the shaft 34.
When the shaft 34 is rotated clockwise, as viewed in
FIGURE 4, the friction-drive connection transmits a sufficient
amount of torque to the paw 36 to rotate the paw 36 from its
unlatched position, as shown in FIGURE 4, to its latched
position, as shown in FIGURE 3. When the paw 36 reaches its
latched position, its stop surface 98 engages the stop 32. If
the shaft 34 continues to rotate in a clockwise direction, the
friction drive connection slips thereby permitting the threaded
portion 80 of the shaft 34 to thread into the threaded hole 92
in the paw 36. As the shaft 34 threads into the hole 92, the
paw 36 is caused to move forwardly along the shaft 34 to
clampingly engage the rear face 18 of the frame 14, whereby the
closure 12 is clamped into secure engagement with the gasket 16.
Referring to FIGURE 5, the washers 38, 40 may be
replaced with a specially configured non-planar washer 138. The
washer 138 has a hole 140 formed there through. A pair of flat
surfaces 142 define opposite sides of the hole 140. The washer
138 has an upper surface 144 and wave-shaped formations 146
which depend from the planar Cody portion of the washer 138.
The washer 138 thus forms an axially compressible structure
which can ye installed over the threaded end portion 80 of the
shaft 34 with the flat surfaces 142 in driving engagement with
the flat surfaces 82. Since the specially configured washer 138
rotates with the shaft 34, the engagement of its upper surface
144 and its depending formations 146 with the housing 110 and
the central portion of the paw. 36 will establish a shippable,
friction-type drive connection which will transmit limited
torque from the shaft 34 to the paw 36.
Referring to FIGURES 6 and 7j an alternate embodiment
of an adjustable-grip latch incorporating features of the
present invention is indicated generally by the numeral 210.
The latch 210 is mounted on a movable closure 212. A frame
structure 214 carries a resilient, compressible gasket 216 for
engaging pyrometrically extending portions of the closure 212
when the closure 212 is closed. The frame structure 214 has a
rear wall 218 which may be engaged and gripped by the latch 210
to securely hold the closure 212 in its closed position. A
mounting hole 220 is formed through the closure 212. Portions
of the latch 210 extend through the hole 220, as will be
explained. A pair of flat surface portions one of which is
indicated by the numeral 222 in FIGURE 6, define opposite sides
of the hole 220.
The principal components of the latch 210 include a
mounting ferrule 230, a stop 232, an operating shaft 234, a paw
236, a drive washer 238 and a wave spring washer 240. The
washers 238, 240 cooperate to establish a shippable,
friction-type drive connection between the shaft 234 and the
paw 236.
The mounting ferrule 230 has a relatively large
diameter head 242, a threaded body 244, and a hole 246 which
extends coccal through the head 242 and the body 244 to
define an axis of rotation for the shaft 234. A pair of flats
248 are formed on opposite sides of the body 244 for engaging
the flat surface portions 222 which define opposite sides of the
mounting hole 220 to prevent the ferrule 230 from turning in the
mounting hole 220. A shoulder 249 is provided at the juncture
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of the head and body portions 242, 244 of the ferrule 230. The
shoulder 249 engages the front face of the closure 12.
The stop 232 is an L-shaped member having a base
portion 250 which engages the rear face of the closure 212, and
a projecting portion 252 which extends rearwardly with respect
to the closure 212. A mounting hole 254 is formed through the
base portion 250. A pair of flat surfaces 256 define opposite
sides of the hole 254. The threaded body 244 of the ferrule 230
extends through the hole 254, and the flats 248 formed on the
body 244 engage the flat surfaces 256 to prevent relative
turning movement between the stop 232 and the ferrule 230. A
pair of stop surfaces 258, 260 are defined on opposite sides of
the projecting portion 252. A nut 262 is threaded onto the body
244 of the ferrule 230. The nut 262 is tightened into
engagement with the base portion 250 of the stop 232 to secure
the ferrule 230 and the stop 232 rigidly in place on the closure
212.
The operating shaft 234 has an operating head 270
formed on its forward end. A radially extending shoulder 272
forms a transition between the operating head 270 and a
cylindrical mounting portion 274. The mounting portion 274
extends through the hole 246 in the ferrule 230, and is
journal Ed by the ferrule 230 for rotation. A circumferential-
extending groove 276 is formed in the mounting portion 274, and
a permanent shoulder retaining ring 278 is seated in the groove
276. The retaining ring 278 engages the back of the ferrule
230, and the shoulder 272 engages the front of the ferrule 230,
whereby the shaft 234 is retained in place with respect to the
ferrule 230.
The operating shaft 234 has a rearwardly extending
portion 280 which is threaded. A pair of flat drive surfaces
282 are formed on opposite sides of the threaded portion 280. A
circumferential extending groove 284 is formed near the rear
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end of the shaft 234~ A resilient retaining clip 286 is seated
in the groove 284.
The paw 236 has a central portion 290~ A hole 292 is
formed through the central portion 290. The threaded portion
280 of the 234 shaft extends through the hole 292 to mount the
paw 236 on the shaft 234.
The paw 236 has projecting arms 294, 296 which extend
in opposite directions from the central portion 290. The arm
294 defines a stop surface 298. The arm 296 is of dog-legged
configuration, and defines a stop surface 299 and a tapered tip
300. The paw 236 is in its latched position when the tip 300
overlies the rear wall 218 of the frame structure 214, as is
shown in FIGURE 7. The paw 236 is in its unlatched position
when the tip 300 is rotated to a position (like that shown in
FIGURE 4) wherein the tip 300 in no way obstructs opening of the
closure 212. When the paw 236 is in its latched position, its
stop surface 298 engages the stop surface 258 formed on the stop
232. When the paw 236 is in its unlatched position, its stop
surface 299 engages the stop surface 260. By this arrangement,
the stop surfaces 258, 260 298, 299 cooperate to limit the range
of rotary movement through which the paw 236 can travel.
The paw 236 has a housing 310 secured to it for
enclosing the washers 238, OWE The housing 310 has outer and
inner flange portions 312, 314 which are joined by an axially
extending shoulder 316. The outer flange 312 is spot welded at
spaced points 318 to the central portion 290. The inner flange
314 has a threaded hole 315 through which the shaft 234 is
threaded. Referring to FIGURE I the housing 310 cooperates
with the central portion 290 of the paw 236 to define a chamber
317 within which the drive washer 238 and the wave spring washer
240 are housed.
The drive washer 238 has a hole 320 formed through it
to receive the shaft 234. A pair of flat surfaces 322 define
opposite sides of the hole 320 and drivingly engage the flat
drive surfaces 282 on the shaft 234. The drive washer 238 has
an outer diameter which lets it turn freely inside the chamber
317 of the housing 310.
The wave spring washer 240 is a non-planar, axially-
compressible spring steel member of a commercially available
type. The washer 240 has a hole 324 formed through it to
receive the shaft 234, and has opposed face portions 326, 328
which can be compressed axially toward each other. The washer
240 is of the type sold by Associated Spring Corporation of
Bristol, Connecticut under the part number U-375- 0090.
The housing 310 and the central portion 290 of the
paw 236 cooperate to compressively sandwich the washers 238,
240 to establish a shippable, friction-type drive connection
between the shaft 234 and the paw 236. on operation, the latch
210 performs in exactly the same manner as the latch 10.
It will be understood that the type of operator head
which is used to rotate the shafts 34, 234 can take any of a
wide variety of forms, and can, if desired, simply comprise a
knob. The operator heads 70, 270 depicted in the drawings are
of the type disclosed in referenced U. S. Design Patent 207,707
and U. S. Utility Patent 4,369,678. A similar operating head
which may be used with latches embodying features of the present
invention is disclosed in referenced U. S. Design Patent
270,229. Tools which may be used to rotate the operator heads
70, 270 are disclosed in referenced U. S. Design Patent 270,424
and U. S. Utility Patent 4,369,678.
Although the invention has been described in its
preferred form with a certain degree of particularity, it is
understood that the present disclosure of the preferred form has
been made only by way of example and numerous changes in the
details of construction and the combination and arrangement of
parts may be resorted to without departing from the spirit and
scope of the invention as hereinafter claimed. It is intended
that the patent shall cover, by suitable expression in the
appended claims, whatever features of patentable novelty exist
in the invention disclosed.
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