Note: Descriptions are shown in the official language in which they were submitted.
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SIDE ACTION FLUSH LOCK FOR CASEMENT WINDOW AND METHOD OF
OPERATING THE SAME
Technical Field
The present invention is directed towards window locks, and more particularly
toward manual handles for actuating window locks. Specifically, the present
invention is directed to a flush mounted or low profile actuating window lock
for
casement windows. More specifically, the present invention is directed to a
flush
mounted lock actuator designed to drive a lock bar that locks and unlocks a
casement window, which protrudes from the window frame significantly less than
prior art designs, while employing an action which operates at 90 degrees to
the
pivoting handle.
Description of Related Art
Generally, a casement window is a window unit in which the single vent cranks
outward, to the right or left. Casement windows are hinged at the side.
(Windows
hinged at the top are referred to as awning windows.) They are used singly or
in pairs
within a common frame. Casement windows are often held open using a casement
stay.
Casement windows open like doors. Like doors, either the left or right side is
hinged
(or, more accurately, pivoted), and the non-hinged side locks securely into
place by a
lock bar driven by a lock handle. Unlike a door, the casement window opens not
by
a knob or handle but by means of some variation of a gear driven operator or
lever,
which is placed around hand height or at the bottom. A gear driven operator,
stay, or
friction hinge controlling the position of the sash is necessary when the
window
opens outward, to hold the window in position during inclement weather, such
as
high winds.
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The locking system for a casement window is typically on the side of the
window.
Lock handles for casement windows are known in the art. Generally, a lock
handle is
mounted on the frame of the casement window and moves an internally mounted
fork component left or right. The fork component drives a lock or tie bar that
is also
mounted to the frame. One type of locking mechanism for a casement window uses
a flat tie bar slideably mounted to the window frame along the open side of
the
window. The tie bar is provided with multiple pins for locking and driving
that
extend perpendicularly outward from the tie bar. A locking handle is provided
on the
interior of the window frame that can be thrown by the user between locked and
unlocked positions. The locking handle slides the tie bar, which moves each
locking
pin between a corresponding locked and unlocked position. A typical lock bar
and
lock handle to drive the lock bar is shown in U.S. Patent No. 7,946,633,
entitled
"Low Friction Adjustable Roller Pin," issued to Minter on May 24, 2011.
Lock handles of the prior art are known to protrude from the casement window
frame at a distance of approximately 20-25 mm. This protrusion is due to the
internal
driving mechanism within the handle. Casement window lock handles of the prior
art drive a fork component, which engages and slides the lock bar. In order to
drive
the fork component from one side to the other, the handle casing must have
sufficient depth to allow for the handle to pivot about the casing and to
allow the
fork internally to shift from side to side.
The most relevant prior art does not teach or disclose a locking mechanism
capable
of low profile (on the order of 8 mm) flush mounting that can be adapted to
work
with existing tie bar locking designs. For example, in U.S. Patent No.
5,087,087
issued to Vetter, et al., on February 11, 1992, entitled "Sash Lock," a basic
multipoint
window lock mechanism is taught using an actuating lever/handle that drives a
sliding lock bar. The actuating lever handle has a pin located at the opposite
end
from the handle end. The pin is engaged in and drives a fork component on the
lock
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bar. This prior art does not disclose, describe, or suggest any type of lifter
mechanism
in combination with the fork component to achieve a significantly reduced
profile
lock actuation. Nor does this prior art design introduce additional linkage to
prevent
back driving the lock.
In U.S. Patent No. 5,813,710 issued to Anderson on September 29, 1998,
entitled
"Flush Lock Actuator," a lock actuator is disclosed to provide a "flush" lock
appearance. However, for reasons discussed further herein, the low profile
feature of
this invention is provided with a design distinctly different from the present
design.
The Anderson design teaches a handle that is symmetrical and flush with the
body of
the actuator. The handle is pivoted with respect to the casing about its
center on a
pin. One end of the handle pivots towards (and into) the window frame, while
the
other end pivots out of the body and away from the frame. The end that pivots
into
the window has an actuating link attached to it that drives the lock bar.
There is no
restrictor arm for redirecting the pivot points of the handle to work in
combination
with a fork component to reduce the casing profile as taught by the present
invention, nor is there a rotatable connector to prevent "over-opening" the
lock.
In U.S. Patent No. 5,829,802 issued to Anderson, et al., on November 3, 1998,
entitled "Multi-Point Lock Operator For Casement Window," a lock actuator is
disclosed that drives a multipoint lock bar. Although the actuator handle is
not flush,
the handle swings a full 180 so that it lies flat at both the locked and
unlocked
limits of motion. The far end of the actuator handle drives a "universal" link
that is
connected to the lock bar. In this design, the handle is pivoted directly on
the casing
or body of the device, which is distinctly different than the present design.
Consequently, there is no need for a restrictor arm or any additional linkage
for over
center security to prevent the lock handle from being back driven.
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In general, the prior art is silent with respect to salient features of the
present
invention that achieve flush mounting and prevent back driving the lock.
Disclosure of the Invention
Bearing in mind the problems and deficiencies of the prior art, it is
therefore an
object of the present invention to provide a casement window lock that is
flush
mounted with a significantly lower profile than the current state of the art.
It is a further object of the present invention to provide a casement window
lock that
allows for complete reversal of the handle from the locking position to the
unlocking
position, and vice versa.
In yet another object of the present invention, it is desirable to provide a
casement
window lock that prevents back driving the locking mechanism.
The above and other objects, which will be apparent to those skilled in the
art, are
achieved in the present invention which is directed to a method of unlocking a
casement window having an elongated casing with a substantially horizontal
sidewall section including a longitudinal slot for receiving a fork component,
and a
restrictor arm pivotally attached at one end to the casing and pivotally
attached at the
other end to a handle at a first pivot point. A fork component is adapted to
engage a
lock bar external to the lock, and the fork component is in slideable
communication
with the casing within the longitudinal slot. A handle is pivotally attached
at one end
to the fork component at a second pivot point and pivotally attached at an
intermediate point on the handle to the restrictor arm, and the handle is
rotatable
along a plane perpendicular to the fork component. The method comprises
rotating
the handle about the first pivot point to move the fork component and the
second
pivot point horizontally along the casing horizontal sidewall section within
the
longitudinal slot in a direction perpendicular to an axis of rotation of the
handle,
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while simultaneously shifting the first pivot point relative to the second
pivot point to
allow said handle to rotate from an initial position.
The elongated casing may comprise a spring action push mechanism including a
permanent magnet embedded at an end opposite the handle second pivot point and
the handle may include a second end having a permanent magnet of opposite
polarity to the first permanent magnet embedded therein, wherein magnetic
attraction between the permanent magnets maintains the handle in a flush
position
within the casing when the handle is in a locked position. The method may
further
include the step of pulsing the handle second end in the direction of the
casing to
compress a spring within the push mechanism such that upon release of the
spring,
energy stored in the compressed spring is sufficient to overcome the magnetic
attraction between the first and second permanent magnets to release the
handle for
rotation.
In an embodiment, the method may include causing an over-center condition by
rotating the handle from a fully unlocked position wherein a first hinge
point,
rotatably joining the handle to the fork component, is placed between a second
hinge point, rotatably joining the handle to the restrictor arm, and a third
hinge
point, rotatably joining the restrictor arm to the casing, and the second
hinge point is
above an action line connecting the first and third hinge points, and
thereafter
causing said over-center condition by rotating the handle fully to a locked
position
such that the second hinge point is placed between the first and third hinge
points,
and the second hinge point is below an action line connecting the first and
third
hinge points.
In another aspect, the present invention is directed to a method of securing a
window sash to a casement window frame, comprising actuating a flush lock for
the
casement window, wherein the casement window includes an elongated casing
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having a substantially horizontal sidewall section including a longitudinal
slot for
receiving a fork component adapted to engage a lock bar external to the lock,
the
fork component in slideable communication with the casing within the
longitudinal
slot. The flush lock further includes a restrictor arm pivotally attached to
the casing,
and a plurality of hinges or pivot points forming an over center linkage to
prevent
back driving the lock, wherein the over center linkage includes, a first hinge
point
rotatably joining the handle to the fork component, a second hinge point
rotatably
joining the handle to the restrictor arm, and a third hinge point rotatably
joining the
restrictor arm to the casing. A handle is pivotally attached at one end to the
fork
component, and pivotally attached at an intermediate point on the handle to
the
restrictor arm, and the handle is rotatable along a plane perpendicular to the
fork
component. The method comprises rotating the handle to an unlocked position,
such
that the first hinge point is between the second and third hinge points and
the second
hinge point is above an action line connecting the first and third hinge
points, or
rotating the handle to a locked position, such that the second hinge point is
between
the first and third hinge points and the second hinge point is below an action
line
connecting the first and third hinge points, and moving the fork component
horizontally along the casing horizontal sidewall section within the
longitudinal slot
in a direction perpendicular to an axis of rotation of the handle.
In yet another aspect, the present invention is directed to a casement window
lock
for securing a window sash to a casement window frame, the lock comprising a
casing having a substantially horizontal sidewall section including a
longitudinal slot,
a restrictor arm pivotally attached at one end to the casing and pivotally
attached at
the other end to a handle at a first pivot point, a fork component including
an
attachment portion for engaging a lock bar and a protrusion for slideably
engaging
the longitudinal slot, and a handle in pivotal communication with the fork
component at one end of the handle at a second pivot point and in pivotal
communication with the restrictor arm at an intermediate point on the handle,
the
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handle rotatable along a plane perpendicular to the fork component. When the
handle is rotated to an unlocked position, the handle pivots about the first
pivot
point, causing the fork component and the second pivot point to traverse
horizontally within the longitudinal slot in a first direction perpendicular
to an axis of
rotation of the handle, and when the handle is rotated to a locked position,
the
handle pivots about the first pivot point in an opposite direction, causing
the fork
component and the second pivot point to traverse horizontally within the
longitudinal slot in a second direction opposite the first direction.
The casement window lock may include a plurality of hinges or pivot points
forming
an over center linkage to prevent back driving the lock. The over center
linkage may
include a first hinge point rotatably joining the handle to the lifter, a
second hinge
point rotatably joining the handle to the restrictor arm, and a third hinge
point
rotatably joining the restrictor arm to the casing, such that when the handle
is in an
unlocked position, the first hinge point is between the second and third hinge
points
and the second hinge point is above an action line connecting the first and
third
hinge points, and when the handle is in the locked position, the second hinge
point
is between the first and third hinge points and the second hinge point is
below an
action line connecting the first and third hinge points.
In an embodiment, the casement window lock may further include a retainer for
securing the lock to a window frame, wherein the retainer is placed on a
window
frame opposite the casement window lock and providing a surface for mounting
screws through the window frame to the lock. The retainer may comprise a slot
extending along a length thereof for receiving at least a portion of the fork
component extending therethrough as the fork component traverses in the first
and
second directions. The retainer may further comprise at least one detent
formed
therein to engage a detent spring coupled to the fork component and located
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between the fork component and the retainer, the detent spring providing
tactile and
audible indication that the fork component has reached an end of travel.
A spring washer may be attached between the restrictor arm and the casing, the
spring washer capable of providing force at minimal deflection.
The casement window lock may further comprise a spring action push mechanism
including a permanent magnet embedded in the casing at an end opposite the
handle second pivot point and the handle may include a second end having a
permanent magnet of opposite polarity to the first permanent magnet embedded
therein, wherein magnetic attraction between the permanent magnets maintains
the
handle in a flush position within the casing when the handle is in a locked
position.
The handle is releasable for rotation by pulsing an end of the handle in the
direction
of the casing to compress a spring within the push mechanism such that upon
release
of the spring, energy stored in the compressed spring is sufficient to
overcome the
magnetic attraction between the first and second permanent magnets.
A snap-on escutcheon may be attached to the casing and the handle, and the
casement window lock may further include a rotatable connector for preventing
the
handle from over-rotating and contacting the casing and/or escutcheon and
ensuring
clearance therebetween as the handle is rotated to an unlocked position.
Brief Description of the Drawings
The features of the invention believed to be novel and the elements
characteristic of
the invention are set forth with particularity in the appended claims. The
figures are
for illustration purposes only and are not drawn to scale. The invention
itself,
however, both as to organization and method of operation, may best be
understood
by reference to the detailed description which follows taken in conjunction
with the
accompanying drawings in which:
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Fig. 1 depicts a perspective view of an embodiment of the flush lock handle
mechanism casement window lock of the present invention, with the handle in
the
closed position.
Fig. 2 is an exploded view of the flush lock handle mechanism of Fig. 1. The
escutcheon and spring action push mechanism are not shown, for clarity.
Fig. 3 is a right side perspective view of a sub-assembly of the flush lock
mechanism
of Fig. 1, showing the connection scheme of the handle, spring action push
mechanism, restrictor arm, and fork. The escutcheon and main casing have been
removed, for clarity.
Fig. 4 is a left side perspective view of the sub-assembly of the flush lock
mechanism
of Fig. 3.
Fig. 5 is a right side plan view of the flush lock handle mechanism of Fig. 1,
showing
the fork translatable within a longitudinal slot in the sidewall of the casing
in a
direction perpendicular to the axis of rotation of the handle.
Fig. 6 is a right side plan view of the flush lock handle mechanism of Fig. 5,
with the
casing removed to show the positioning of over center linkage including three
hinge
points depicted with the handle in the closed position.
Fig. 7 is a bottom plan view of the flush lock handle mechanism of Fig. 1.
Fig. 8 is a perspective view of an embodiment of the flush lock handle
mechanism
casement window lock of the present invention, with the handle in the fully
opened
position.
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Fig. 9 is a right side perspective view of a sub-assembly of the flush lock
mechanism
of Fig. 8. The escutcheon and main casing have been removed, for clarity.
Fig. 10 is a left side perspective view of the sub-assembly of the flush lock
mechanism of Fig. 9.
Fig. 11 is a right side plan view of the flush lock handle mechanism of Fig.
8,
showing the fork translated within a longitudinal slot in the sidewall of the
casing as
the handle rotated to the open position.
Fig. 12 is a right side plan view of the flush lock handle mechanism of Fig.
11, with
the casing removed to show the positioning of over center linkage including
three
hinge points depicted with the handle in the open position.
Fig. 13 is a bottom plan view of the flush lock handle mechanism of Fig. 8.
Fig. 14 is a perspective view of the flush lock handle mechanism casement
window
lock of the present invention installed in a window frame, with the handle in
the
locked position. A portion of the window trim has been removed to show the
interconnection between the lock handle mechanism fork and the lock bar.
Fig. 15 is a perspective view of the flush lock handle mechanism casement
window
lock of Fig. 14, with the handle in the open position.
Mode(s) for Carrying Out the Invention
In describing the embodiments of the present invention, reference will be made
herein to Figs. 1-15 of the drawings in which like numerals refer to like
features of
the invention.
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Certai n terminology is used herein for convenience only and is not to be
taken as a
limitation of the invention. For example, words such as "upper," "lower,"
"left,"
"right," "horizontal," "vertical," "upward," "downward," "clockwise," and
"counterclockwise" merely describe the configuration shown in the drawings.
For
purposes of clarity, the same reference numbers will be used in the drawings
to
identify similar elements.
Additionally, in the subject description, the word "exemplary" is used to mean
serving as an example, instance or illustration. Any aspect or design
described herein
as "exemplary" is not necessarily intended to be construed as preferred or
advantageous over other aspects or design. Rather, the use of the word
"exemplary"
is merely intended to present concepts in a concrete fashion.
The lock of the present invention is a low profile, flush design, that
protrudes from
the window frame significantly less than the prior art, at about 8 mm compared
to 25
mm in the current prior art designs. When locking a casement window, the
window
is closed generally by a crank. The strikes on the moving sash are brought
close to
the pins on a tie bar mounted to the non-moving window frame. The lock handle
is
then thrown. This drives a fork component within the lock, which engages the
tie bar
and drives it, moving the tie bar pins into engagement with corresponding
hooks or
strikes. The fork component is preferably a flat structure adapted to slide
within the
lock casing, preferably having two extensions, such as leg portions, for
engaging a tie
bar. The strikes generally have a ramp surface at their mouth and the pins
slide up
this ramp into engagement. This motion pulls the sash tightly against the
window
frame generating compression for sealing the sash to the window frame.
To achieve this "flush," low profile appearance, the locking mechanism of the
present invention introduces a longitudinal slot in a sidewall of the casing
for the
lock, wherein a fork component translates within the slot in a direction
perpendicular to an axis of rotation of the handle, and the handle is
rotatable along a
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plane perpendicular to the fork component. There is a restrictor arm for
redirecting
the pivot points of the handle to work in combination with a fork component to
reduce the casing profile. As the fork component transitions horizontally
along the
elongated sidewall of the casement window lock, the pivot point of the handle
and
the restrictor arm shifts relative to the fork component to allow the handle
to rotate
approximately 150 from an initial position. In prior art designs, the handle
directly
drives a fork component or the tie bar ¨ structural limitations that result in
a higher
profile appearance. In the present design, the handle is allowed to move more
deeply into the lock mechanism to reduce the height of the lock casing.
Fig. 1 depicts a perspective view of the flush lock mechanism 100 of the
present
invention, with the handle in a closed position. The lock is mounted to the
frame of
a casement window (Figs. 14-15). Unique to the present invention is a
longitudinal
slot 14 in the sidewall of main casing 1 to accommodate the horizontal
movement of
fork component 5 by handle 7 that establishes the locking and unlocking
functions.
Fork component 5 translates within the slot 14 in a direction perpendicular to
an axis
of rotation of the handle 7, as the handle rotates along a plane perpendicular
to the
fork component 5. For exemplary purposes only, the elongated sidewalls of the
casing will be deemed to be in a horizontal direction, and movement by fork
component 5 will be considered movement in the horizontal direction. These
assigned directions are provided only to facilitate descriptions regarding
movement
of components with respect to the casement window lock; they do not represent
direction of the casement window lock after it is mounted on a window frame.
(It is
noted that casement window locks are generally mounted so that the elongated
casing is positioned vertically, as shown in Figs. 14-15.) A snap-on
escutcheon 4, 4A
covering the handle and internal components of the lock, respectively,
presents a
more aesthetically pleasing appearance when the flush lock mechanism is
installed,
for example, in a wooden frame for a window. The escutcheon may be colored or
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comprise a design pattern on a surface thereof to blend in or match the wood
of the
window frame.
Fig. 3 depicts a subassembly 120 of the flush lock mechanism of the present
invention,
with the escutcheon 4 and casing 1 removed, for clarity. As shown in Fig. 3,
lock
mechanism 100 includes a lever arm or handle 7, pivotable about a restrictor
arm
comprising sides 2A, 2B through a hinge or pivot pin 11 at an intermediate
point of the
handle.
Preferably, restrictor arm 2A, 2B is riveted to handle 7; however, other
attachment
schemes may be employed provided handle 7 is rotatably attached to restrictor
arm 2A,
2B at the desired pivot location. Pivot pin 11 is preferably located at an
intermediate point
on handle 7 between the handle endpoints at a distance closer to the main
casing 1 and
escutcheon than the handle's grip portion end 16. This allows for greater
mechanical
Leverage by a user when pulling handle 7 upwards or pushing handle 7
downwards. In
an embodiment, as shown in Fig. 3, a spring action push mechanism 70 may be
embedded in casing 4 near the handle grip portion 16. Push mechanism 70 acts
to
maintain the handle 7 in a flush position relative to the casing when handle
is in the
locked position, and to release the handle for rotation to the unlocked
position, as will
be described in further detail below. Flush lock handle mechanism 100, in its
operating
condition, is encased in snap-on escutcheon 4 and main casing 1. In Fig. 3,
the snap-on
escutcheon 4 has been removed for clarity.
Fig. 3 further illustrates the connection of handle 7 to restrictor arm 2A, 2B
via pivot pin
11 at an intermediate point from each end of handle 7, as well as the
connection of fork
component 5 to an end of handle 7, rotatable about a hinge, pivot pin 10. As
shown, handle
7 is designed to pivot about restrictor arm 2A, 2B and fork component 5 via
pivot pins 10
and 11, respectively. Unlike the prior art, handle 7 is not directly connected
to, nor does
it pivot directly about, main casing 1 or
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escutcheon 4. As discussed further herein, this linkage contributes to the low
profile
design of the lock mechanism and the over center operation that prohibits back
driving the flush lock mechanism.
A fork component 5 is employed that is similar to some prior art designs,
insomuch
as a fork component is used to engage a tie bar during locking and unlocking
actuation. As shown in Figs. 14-15, fork component 5 drives a tie bar or lock
bar that
is mounted to the frame. The tie bar engages a series of strikes that are
mounted to
the moving sash. Once the tie bar is engaged with the strikes, the window is
locked.
One end of handle 7 pivotally connects to fork component 5 via hinge or pivot
pin
10, which may be a rivet or other rotatable, pivoting attachment. The opposite
end of
restrictor arm 2A, 28 is pivotally connected to casing 1 via hinge or pivot
pin 12.
Upon actuation of the handle 7, as the fork component 5 transitions
horizontally
within slot 14 along the elongated sidewall of the casement window lock, the
pivot
pin 11 connecting the handle and restrictor arm shifts vertically, as well as
transversely, relative to pivot pin 10 to allow the handle to rotate from an
initial
position. In one embodiment, handle 7 is permitted to rotate approximately
1500
from its initial position, as shown in Fig. 9.
Fig. 2 is an exploded view of the flush lock handle mechanism 100. Fork
component
includes an extension or protrusion 6, protruding from said fork component
body
for engaging longitudinal slot 14 in the sidewall of the casing. As further
shown, fork
component 5 may include a track segment 8 on its body that receives an
extension
or lip protruding from the top portion of slot 14. Handle 7 is received
between two
raised portions of fork extension 6, each raised portion comprising an
aperture for
receiving pivot pin 10 therethrough to pivotally connect handle 7 to fork
component
5 (Figs. 3-4).
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Fig. 4 depicts a left side perspective view of the sub-assembly of the flush
lock
mechanism shown in Fig. 3, with a snap-on escutcheon 4A shown covering the top
portion of handle 7. As shown in Figs. 3-4, the subassembly may further
include a
spring action magnetic push mechanism 70 for maintaining the handle in flush
position relative to the casing 1 when in a locked position. Embedded in the
push
mechanism is spring action pedestal 71 and at least one permanent magnet 72
having a polarity opposite permanent magnet 73 which may be embedded in an end
of handle 7 opposite pivot pin 10 (Fig. 9). The distance, and therefore the
strength of
magnetic attraction, between magnets 72, 73 is such that to release the handle
for
rotation, a user may pulse the end 16 of the handle downward in the direction
of
casing 1 to compress spring pedestal 71, and upon release, the energy stored
in the
compressed spring upon returning to its normally biased state is sufficient to
overcome the magnetic attraction between magnets 72, 73, resulting in handle 7
being freely rotatable after being biased upwards by the spring action
pedestal 71.
Fig. 5 depicts a side plan view of the flush lock handle mechanism of the
present
invention. Handle 7 is in the locked position and maintained flush within
casing 1
by the magnetic attraction between magnets 72, 73. Fork component 5 is shown
in
its right most position prior to translation within longitudinal slot 14 in
the sidewall
of the casing 1 as the handle rotates along a plane perpendicular to the fork
to open
the lock. As shown in Fig. 2, fork component 5 includes an extension or
protrusion
6, protruding from said fork component body in a direction perpendicular to
the
horizontal motion of travel of fork component 5 that may be a pin or a
slightly
elongated oval or rectangular shaped segment for slideably engaging
longitudinal
slot 14. Extension or protrusion 6 may be integral with, or attached to, fork
component 5. As shown in Fig. 2, in an embodiment, fork component 5 may
include
a track segment 8 on its body that receives an extension or lip protruding
from the
top portion of slot 14. In either attachment scheme, fork component 5 is able
to slide
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horizontally in slot 14 along the elongated horizontal casing structure when
induced
by the actuation of handle 7.
The relationship between the hinged points of the present invention interplays
with
the translation of the motion of handle 7 and fork component 5.
As shown in Fig. 6, hinge A or pivot 10 is the pivotal junction of handle 7
and fork
component 5. Hinge B or pivot 11 is the pivotal junction of handle 7 with
restrictor
arm 2A, 2B at an intermediate point on handle 7. Hinge C or pivot 12 is the
pivotal
junction of restrictor arm 2A, 2B with the casing, as shown in Fig. 5.
Fig. 6 is a cross-sectional view of the lock mechanism of the present
invention with
main casing 1 removed, depicting the positioning of three hinge points A, B, C
when
handle 7 is in the locked position. Hinge B is shown below the line of action
50
between hinges A and C. This relationship allows for the locking mechanism to
utilize over center linkage at the ends of travel, and prevents the system
from being
back-driven (i.e., someone trying to break into the window by reversing the
locking
mechanism). Since hinge B is below the line of action 50 between hinges A and
C,
the system is not back drivable. In this manner, this configuration produces a
"three
bar linkage" design. It also allows handle 7 to move over a very wide
operating angle
and return to a flush or low profile position. The first of the three bar
links is formed
by handle 7 between the pivot 10 (hinge A) connected at fork component 5 and
pivot 11 (hinge B) connected at restrictor arm 2A, 2B. A second bar or link is
formed
by restrictor arm 2A, 2B and pivots at each end thereof (hinges B and C). The
third
bar or link of the three bar linkage is created by fork component 5 (hinge A)
and the
horizontal sliding motion of fork 5 component relative to the fixed pivot
point 12 of
the restrictor on the body of the casing (hinge C). The three bar linkage uses
these
three links pivotally connected at the ends (pivot points) so that the three
links can
move relative to each other.
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When handle 7 is at either end of its travel, the three bar linkage design
moves one
pivot or hinge on the handle to an over center position relative to the two
other pivot
or hinge points. This over center position prevents the tie bar or lock bar
from being
back driven to the unlocked position when an "opening" force is applied to
rotate
handle 7. As shown in Fig. 6, when handle 7 is down (or in the locked
position), the
pivot connection (hinge B) between handle 7 and restrictor arm 2A, 2B will be
below line of action 50 defined between the pivot point of the handle and fork
component (hinge A) and the fixed pivot point between the restrictor arm and
the
casing body (hinge C).
At the other extreme, as shown in Fig. 12 with handle 7 fully open, the second
pivot
connection on the handle (the pivot point on restrictor arm, hinge B) will
have
moved past and above the line of action 50 defined between the first pivot
point on
the handle at the fork component (hinge A) and the fixed pivot point between
the
restrictor arm and the body of the casing (hinge C). In each case, a hinge
point
moves "over center" to prevent the lock mechanism from being reverse driven.
In
other words, one of the three pivot points moves across a line of action that
connects
two other pivot points.
Figs. 8-12 depict the handle 7 in a fully opened position. In a preferred
embodiment,
pivot pin 11 or hinge B gradually shifts vertically, as well as transversely,
from the
horizontal over the length of travel as the fork component moves horizontally
within
slot 14 along main casing 1, perpendicular to the axis of rotation of the
handle, as
the handle rotates from a locked to an unlocked position. Without such rising,
a
binding condition would be experienced as the fork component is moved through
its
horizontal transition. Thus, in the preferred embodiment, actuating handle 7
serves
to move pivot pin 11 simultaneously to a raised (or lowered) position while
the fork
component 5 is moved horizontally within slot 14, as the handle rotates
between
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locked and unlocked positions. This allows handle 7 "clearance" to rotate
about its
pivot points without requiring extra depth to the casing, and in fact,
reducing the
depth of the casing, making the casement window lock more flush with the
mounting frame.
As further shown in Figs. 8-12, in an embodiment, the present invention
includes a
rotatable connector 80 for preventing the handle 7 from over-rotating and
contacting
escutcheon or casing. As the handle is rotated to an open position, connector
80
acts as a stop to prevent handle 7 from rotating into escutcheon 4 and
ensuring
clearance therebetween (Fig. 8).
In order to assemble the lock mechanism to the frame of a window, a retainer
60 is
used. Retainer 60 provides a surface for mounting screws to bear down on.
Referring again to Fig. 2, and also shown in Figs. 3-4 and 9-10, is an
embodiment of
the retainer 60 of the present invention. Retainer 60 is an elongated, flush
component, having a slot or track 62 extending along a length thereof for
receiving a
portion of fork component 5 when the fork component translates within casing
slot
14 as handle 7 is rotated between open and closed positions. Retainer 60
further
includes a pair of indentations 63 indicating the ends of travel of the fork
component
as the handle is rotated. Two screw holes 68 are introduced at approximately
each
end for mounting the flush lock mechanism.
In an embodiment of the present invention, there is a detent at both ends of
travel
(open and locked). A detent spring 9 (refer to Fig. 2) is located underneath
fork
component 9, between the fork component and retainer 60. Detent spring 9
provides tactile and audible indication that the lock mechanism has reached
its end
of travel. Additionally, a detent helps sustain handle 7 in the correct
position at its
end of travel.
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Figs. 2-7 and 9-13 depict a retainer 60 having preferred shaped detents 63 to
receive
and accommodate detent spring 9 as fork component 5 translates within slot 14.
Fig. 7 depicts a bottom plan view of the lock mechanism in the locked detent
position (detent spring 9 is engaged with the right-sided indentation or
detent 63)
when the handle is in the locked position, while Fig. 13 depicts a bottom plan
view
of the lock mechanism in the unlocked detent position (detent spring 9 is
engaged
with the left-sided indentation or detent 63) when the handle is in the
unlocked
position.
To further assist with handle stability during operation, a spring washer 3 is
preferably employed between restrictor arm 2 and main casing 1 (Figs. 2-3).
This
spring washer, preferably a Belleville spring washer, is capable of providing
large
amounts of force with very little deflection, thus allowing the present
invention to
provide upwards of 75 pounds of load with two-tenths of one millimeter (0.2
mm) of
deflection. Spring washer 3 also accommodates production variances while
maintaining a pre-load force on restrictor arm 2.
Fig. 3 depicts a partial perspective view of the subassembly showing spring
washer 3
in position.
The present invention achieves a low profile casement window lock that far
exceeds
the profile depth of casement window locks of the prior art by introducing a
longitudinal slot in a sidewall of the casing for the lock, wherein the fork
component
translates within the slot in a direction perpendicular to an axis of rotation
of the
handle as the handle rotates along a plane perpendicular to the fork
component. The
present invention establishes a locking structure with multiple pivoting
points that
allows the handle to rotate completely with minimally required clearance in
the
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casing housing. The pivoting action of the handle and restrictor arm allows
the
handle to move the fork component horizontally while raising or lowering the
restrictor arm pivot pin in relation to the fork component, with the fork
component in
slideable communication with a longitudinal slot in a sidewall of the casing.
The
multiple pivoting action provides for a three bar linkage that secures the
casement
window lock in either the open, unlocked position, or closed, locked position,
and
prevents back driving the lock mechanism in the reverse direction.
While the present invention has been particularly described, in conjunction
with
specific embodiment(s), it is evident that many alternatives, modifications,
and
variations will be apparent to those skilled in the art, in light of the
foregoing
description. It is therefore contemplated that the appended claims will
embrace any
such alternatives, modifications, and variations as falling within the true
scope and
spirit of the present invention.
Thus, having described the invention, what is claimed is:
