Mechanical linkage sash displacement device

A sash is displaced manually by the exertion of force upon a frontal bar rigidly connected to the distal ends of a first pair of arms spaced apart from each other extending perpendicularly from opposed jambs pivoted at proximate ends. A second pair of arms, similarly spaced apart from each other, is pivoted to the sash at proximate ends above the first arm pivots to the jambs, the distal ends being pivoted to the first arms at a point medial the first arm ends. The length of each arm and the distance between congruent connections is equivalent and all six pivots enable rotation in planes perpendicular to the sash. The frontal bar, the first arms and the two pivots connecting congruent pairs of arms are displaced in an arc with respect to the sash and jambs and linear displacement of the sash by this linkage is effected with a basic mechanical advantage equal to the length of the first arm divided by the radius of the arc described by the either pivot between paired arms. The linear travel of the sash is related to the arcuate displacement of the frontal bar by the tangent of the second arm taken to the pivot arc which varies continuously. The total travel equals twice the pivot arc radius. The rate of sash travel as a function of arcuate displacement, the precise inverse of the overall mechanical advantage, is greatest when the pivot between arms is in the portion of the arc above perpendicular to the face of the closure. Conversely, the rate of travel is least and the mechanical advantage is greatest in the pivot arc lower portion proximate the jambs. The mechanical advantage provided by this linkage thus varies to provide the most advantage when it is most needed, initially from the closed position, and provides the greatest rate of sash travel where manual effort is most easily exerted. This linkage also provides automatic exterior locking of the sash in the closed position. Reach over a frontal barrier is also facilitated with an optional auxiliary bar offset from and parallel to the frontal bar and more further mechanical advantage is obtainable with an auxiliary arm connected by ratchet to one of the first arms.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The general field of the present invention is that of slidable 
reciprocating closure devices, more particularly slidable multi-sashed 
closures between opposed jambs within a fully bounded frame, specifically 
devices assisting in displacement of such sashes within such frames. 
2. General Background 
Devices assisting in the ease of operating vertically hung sash windows 
have historically involved a mechanism using a sash cord or chain 
connected to a sash and run over a pulley to a sash weight inside the 
window frame exterior the jambs wherein the weight acts as a counter 
balance to the sash. More recently, spring loaded mechanisms which release 
energy assisting displacement of the window in opening and which store 
energy and thus retard displacement in closing have gained prevalence in 
the current market for residential construction in the United States. 
Many people lacking strength or mobility in the upper body have difficulty 
in operating such windows. This problem is exacerbated by any barrier 
disposed in front of the closure which prevents the placing of one's 
person immediately proximate the frame of the closure as in the case of a 
window disposed behind and above a kitchen sink, for example. In 
consequence of such location a person desiring to displace the window must 
extend their arms a substantial distance and cannot exert more than a 
small fraction of the strength available in a proximate situation upon 
this distally located window in order to operate the same. 
DISCUSSION OF THE PRIOR ART 
The specific problem set forth immediately above has received direct 
attention by the prior art. The present inventor and author concur that 
U.S. Pat. No. 4,516,355 issued May 14, 1985 to Dan Basil is considered to 
be the disclosure most pertinent to the present invention known to said 
inventor and author. Aspects of this disclosure include objects of the 
present invention. The structure of Basil's disclosure is simply that of 
two parallel "lift guides" attached to the opposed vertical sash members 
of the lower sash of a double hung sash window acting as auxiliary guides 
along the vertically disposed jambs in conjunction with a U shaped bar 
comprising "lift arms" extended horizontally from the lower sash outward, 
presenting a parallel bar portion medial to the arms spaced apart from and 
rigidly connected to the lower sash. 
This cantilevered bar reduces the reach over a barrier required to operate 
a window and enables the exertion of force upon a fulcrum rigidly fixed to 
the lower sash member, causing a moment about the juncture of the lift 
arms with the sash which promotes binding of the sash within the jambs. 
Because the lever is fixed no mechanical advantage can be obtained in 
regard to displacement of the sash, which condition is evidenced by the 
simple observation that the sash is displaced an amount equal to the 
displacement of the "lift arms". 
Other references pertaining to assistance in the operation of multiple sash 
closures, such U.S. Pat. No. 820,231 issued to Merryweather for a `Handle 
Attachment for Window Sashes`, and U.S. Pat. No. 610,135 issued to Green 
for a `Sash Lift`, or U.S. Pat. No. 1,620,817 issued to Huyard for a 
`Window Sash Attachment` are further mentioned as devices which do not 
provide any genuine mechanical advantage in operation but assist in 
displacement by providing an auxiliary purchase or reaction point for the 
exertion of force upon the sash. The Basil disclosure is the only 
disclosure known teaching the use of a frontal bar portion parallel and 
offset from the face of the closure operable upon a sash. No disclosure of 
a mechanical linkage utilized to displace a sash within a bounded frame is 
known in the prior art. 
The usage of mechanical linkage to obtain mechanical advantage in the 
operation of a reciprocating closure considered closest to the present 
invention is a device commonly used to operate furnace doors, such as that 
disclosed in U.S. Pat. No. 1,539,170 issued to Eddison. In this and other 
known uses of mechanical linkage to operate a reciprocating closure the 
frame is not fully bounded and the linkage is connected with the door 
through an open edge of the frame, essentially within the plane of the 
door and is operated from the side of the door. This is in marked contrast 
to a double hung sash window or horizontally sliding glass door which is 
also a commonplace in current residential construction wherein the closure 
must seal the area within a fully bounded frame and manual operation must 
necessarily be from in front of the closure. 
STATEMENT OF NEED 
It is therefore considered that a need exists for a device which will 
assist in manual operation of multi-sashed, fully bounded reciprocating 
closures by providing a mechanical advantage with regard to displacement 
of such a sash and which will further facilitate operation from a distance 
in front of the closure. 
SUMMARY OF THE INVENTION 
The object of the present invention is a device utilizing mechanical 
linkage which, properly installed, will provide mechanical advantage in 
manual operation of a multi-sashed, fully bounded closure and which will 
further facilitate operation from a distance in front of said closure. 
A pair of first arms each rigidly attached at the distal end to a bar 
frontally disposed parallel to the closure is considered. Each first arm 
is pivoted at the proximate end to a jamb and the distal end of a second 
arm is pivoted to each first arm at a position medial to both said ends of 
the first arm. The proximate end of each second arm is pivoted to one 
sash. The effective lengths of congruent distances between pivots of the 
two pairs of linked first and second arms and connection to the frontal 
bar are substantially equivalent and the pivots enable rotation of each 
arm in substantially parallel planes substantially perpendicular to the 
face of the closure. 
The linkage thus described is intended to be installed in front of an 
interior face of a fully bounded, multiple-sashed closure. Mechanical 
advantage in operation of one sash is thereby provided equivalent to the 
effective length of each first arm divided by the distance between the 
pivot of the first arm to the jamb and the pivot connecting the first and 
second arms together. Linear displacement of the sash with respect to the 
jambs as effected by the arcuate displacement of the frontal bar is 
dependent upon the tangent of the second arm with respect to the arc 
described by the pivot between arms. This tangent is greatest and the 
corresponding rate of sash displacement is greatest when the pivot between 
the arms is in the portion of the arc proximate the pivoted connection of 
the second arm to the sash. 
An automatic locking feature of the sash properly connected to the linkage 
described is provided in the closed position with the frontal bar 
proximate the face of the closure. The frontal bar is adjustable in 
effective length to correspond with varying closure width; the preferred 
embodiment herein utilizing telescoping bar elements, along with an outer 
sleeve cut to length to provide a uniform appearance. The effective length 
of the pivot arc radius as a fraction of the total first arm length is 
further adjustable and both the sash travel available and the basic 
mechanical advantage provided by the device are inversely variable in 
accordance with the relative length of the pivot arc radius with the first 
arm effective length. 
Additional means of further facilitating reach of the device over a barrier 
disposed in front of and below the closure is provided with an auxiliary 
frontal bar rigidly disposed parallel to and spaced apart from the frontal 
bar. Also, extension of the first arms by a ratchet connection further 
provides additional mechanical advantage if desired and the auxiliary 
frontal bar can be connected by auxiliary arms connected by a ratchet.

DETAILED DESCRIPTION OF THE INVENTION 
With reference to FIGS. 1 & 3 wherein a preferred embodiment of the 
principles relating to the present invention is depicted one may discern a 
displacement device 10 comprised of a pair of first arms 11, a pair of 
second arms 12, a frontal bar 13 which, in this preferred embodiment, is 
further comprised of two lateral elements 14, a medial element 15 and a 
slit tube sleeve 16, and connections between the two arms and of each arm 
to either the sash 17 or a jamb 18 by means of a pivot 19. As clearly seen 
in FIG. 1, each first arm 11 possesses an effective first arm length 21 
equal to the distance between the pivot 19 connecting the proximate end of 
the first arm 11 to the jamb 18 and the connection of the distal end of 
the first arm 11 to the frontal bar 13. The second arm 12 similarly 
possesses an effective second arm length 22 equal to the distance between 
the pivot 19 connecting the proximate end of the second arm 12 to the sash 
17 and the pivot connecting the distal end to the first arm 11. 
The position of the pivot 19 between arms is redial to the ends of the 
first arm 11 and is adjustable, as indicated by the three in line pivot 19 
positions depicted in FIG. 1. The position of this pivot determines both 
the available total available sash travel 27, depicted in FIG. 3, and the 
basic mechanical advantage available. The total sash travel 27 available 
is simply equal to twice the pivot arc radius 24 depicted in FIG. 4 which 
is the distance between the pivot 19 connecting the first arm 11 with the 
jamb 18 and the position of the pivot 19 between the arms. Since the 
effective length 21 of the first arm 11 is fixed, and the pivot 19 between 
the arms is adjustable along the medial portion of the first arm 11, the 
pivot arc radius 24 is adjustable as a greater or lesser proportion of the 
effective first arm length 21 which length divided by the pivot arc radius 
24 yields the basic mechanical advantage of the displacement device 10. It 
is further noted that this mechanical advantage and the travel 27 
permitted are inversely related; the greater the pivot radius 24, the 
greater the sash travel 27 enabled and the less mechanical advantage 
derived. 
The pivot arc 25 displacement, a proportion of the first arm arc 26 
displacement, effects the displacement of the sash, ie. sash travel 27, 
through a linkage with the second arm 12 that depends upon the relation of 
the tangent of the axis of the second arm 12 with respect to the pivot arc 
25 depicted in FIG. 4. A graphical representation of this relation is 
depicted in FIG. 5 wherein the point of greatest tangent value, one, is 
seen to be the point of inflection of the curve illustrated therein. While 
numerical values for dimensions are of no special significance, the 
relation between certain effective distances is essential to the 
principles relating to the present invention. As aforementioned, the 
maximum sash travel 27 permitted is twice the pivot arc radius 24, and the 
basic mechanical advantage derived is given by the effective first arm 
length 21 divided by the pivot radius 24. The total effective mechanical 
advantage is not so simply obtained, however, as it is inversely dependent 
upon the relation of the tangent of the axis of the second arm 12 with 
respect to the pivot arc 25. 
This relation may be described by an integral possessing the basic 
mechanical advantage as a constant taken over the available range of 
arcuate displacement for the tangent of the axis of the second arm 12 with 
respect to the pivot arc 25 which is continuously variable and therefore 
presents a rather difficult mathematical model. Alternatively, reference 
may be made to FIG. 5 wherein the linear displacement of the sash 17 
herein known as the sash travel 27 is shown as a function of displacement 
through the pivot arc 25, expressed in percentage of the effective pivot 
radius 24 as a function of degrees from closed for an embodiment of the 
principles relating to the present invention possessing a basic mechanical 
advantage of 2.305. 
Omitting the extreme ten degrees, (10.degree.), on either side physically 
unavailable for arcuate displacement, combined with an effective first arm 
length 21 of 2.34 pivot radii 25, the first arm arcuate displacement may 
be readily calculated to be 
(160.degree./180.degree.)(.pi.)(r)=0.88900(.pi.)(2.34 pivot radius 
25)=6.53 pivot radii 25. Compared with the total linear sash displacement 
27 effected thereby, 2.00 pivot radii 25, one readily finds an overall 
mechanical advantage of 6.53/2.00=3.27 which is an average value for an 
effective mechanical advantage which varies widely in a complex relation 
most readily understood as the inverse of the slope of the complex curve 
depicted in FIG. 5. It is apparent from this curve that the greatest 
mechanical advantage is derived when the frontal arm 13 is proximate the 
face of the closure 20, as in the closed position depicted in FIG. 1 & 2, 
and is least wherein the position of the second arm 12 is perpendicular to 
the first arm 11 and the tangent between the axis of the second arm 12 
with respect to the pivot arc 25 is maximum which is also the inflection 
point in the curve seen in FIG. 5. 
It is further seen in the graphical representation depicted in FIG. 5 that 
the rate of linear sash displacement 27, (the slope of the curve), does 
not become great until approximately 90.degree., when the first arm 11 is 
perpendicular to the face of the closure 20 and the frontal bar 13 is 
extended furthest from the face of the closure 20 and is in the position 
that best accommodates the exertion of force upon the same from someone in 
front of the device 10 and the closure 20. The steepest portion of the 
curve seen in FIG. 5, moreover, comprises the range roughly between 
90.degree. and 150.degree. with the mean value of that range, 120.degree., 
being the inflection point of maximum rate of displacement. 
In relation to a physical device constructed and installed in accordance 
with the principles relating to the present invention, the device is 
easiest to operate where it is most difficult to reach and apply force, 
when the frontal arm 13 is closest to the closure 20 and must be pulled 
outward. And the displacement through the portion of the first arm arc 26 
between 90.degree. and 150.degree. from closed rapidly effects most of the 
total sash displacement 27 with the frontal bar 13 being pushed in 
extension of one's arms from the point where the frontal bar is closest, 
90.degree.. It is thus seen that the mechanical advantage, which varies 
inversely with the rate of linear sash displacement 27 as a function of 
the first arm arcuate travel 26 is complex and varies in a manner that 
optimizes the manual effort available for operation of a reciprocating 
sash 17 from a position in front of the closure 20. 
A device properly constructed and installed in accordance with the 
principles relating to the present invention further provides automatic 
locking of the sash 17 within the frame 28 when disposed in the closed 
position depicted in FIGS 1 & 2. This alleviates the operator of the need 
to reach to the top of the lower sash in the case of a double hung window 
and throw the lock or locks typically positioned thereon which, in the 
case wherein a barrier is disposed in front of and beneath the window, 
constitutes an action which is difficult for many people lacking either 
the upper body mobility, dexterity or the reach necessary to operate such 
locks so disposed. 
It is also noted that many double sash hung windows possess pivoted 
connections slidable in the jambs which may be utilized to pivot the 
entire sash outward for ease in cleaning the exterior face of the window. 
If properly installed, a preferred embodiment of the principles relating 
to the present invention will not interfere with operation of this feature 
as each pair of linked congruent arms may be disposed such that all the 
arms are lateral to the face of the entire sash 17, as depicted in FIG. 1. 
The frontal bar 13 of this preferred embodiment is substantially parallel 
with the sill of the frame 28 in the closed position depicted in FIG I and 
it is readily seen that no obstruction to the front face of the entire 
sash 17 is made by the device 10. 
Two basic options additional to the preferred embodiment of the principles 
relating to the present invention discussed above are considered. With 
reference to FIG. 2, an auxiliary frontal bar 33, parallel to and spaced 
apart from the frontal bar 13, connected by arms disposed perpendicular to 
the first arm 11, is depicted in side view. It is not necessary that the 
arms connecting this auxiliary frontal bar 33 to the linkage comprising 
the basic device 10 be perpendicular to the first arm 11, but this yields 
the greatest assistance in overcoming the reach over a barrier disposed in 
front of and beneath a reciprocating closure 20. 
In regard to obtaining further mechanical advantage in the operation of a 
device 10 constructed in accordance with the principles relating to the 
present invention, an auxiliary arm 31 pivotally connected to a first arm 
11 or the frontal bar 13 by means of a ratchet 29 as depicted in FIG. 4 is 
recommended. The additional mechanical advantage obtained is the 
additional length in leverage to the effective first arm length 21 which 
total is divided by the pivot arc radius 24 to yield the basic mechanical 
advantage derived from the device 10. The ratchet 29, should be oriented 
such that the pawls engage in the direction of increasing first arm arc 26 
from the closed position and pivot freely in the opposite direction, in 
order to further facilitate reduced effort required in opening the closure 
20. 
Construction of a preferred embodiment of the principles relating to the 
present invention may be in any suitable material by any suitable means. 
However, hollow aluminum bars of hollow rectangular cross section are 
recommended for the arms and aluminum tube lateral elements 14 of the 
frontal bar 13 are recommended in conjunction with a wooden dowel 
comprising the medial element 15 and a slit thin wall length of plastic 
tubing comprising the sleeve 16 which, cut to length at the time of 
installation, provides an aesthetically pleasing cover for the telescoping 
lateral and medial elements and thus a range of closure widths is readily 
accommodated. The pivots 19 are standard hardware and the entire 
construction including installation is well within the abilities of one 
skilled in the art. It is further recommended, however, that attention be 
given to flush fitting of the connections, particularly with respect to 
the overall width of the device as many jambs are within very close 
proximity to a wall perpendicular to the face of the closure. To this end, 
countersinking of bolt heads and use of pop rivet style nuts is 
recommended for connection of aluminum hollow bar and tube stock. It is 
also suggested that construction and installation locate the frontal bar 
13 in the closed position parallel to the sill in application upon a lower 
sash window as depicted in the figures attached. 
Lastly, it is noted that while the present invention has been discussed 
with reference to figures depicting a double hung sash style window as the 
reciprocating closure 20 fully bounded within a frame 28 including two 
opposed jambs 18, this discussion readily applies to horizontally sliding 
windows, for instance, wherein the jambs are horizontal, the number of 
sashes easily exceeds two and the device 10 built in accordance with the 
principles relating to the present invention would be disposed such that 
the frontal bar 13 would be vertical instead of horizontal. The utility of 
such an embodiment in accordance with the principles relating to the 
present invention is readily grasped by one practiced in the art as are 
other applications. 
The foregoing is intended to enable a thorough understanding of the 
principles relating to the present invention so that one practiced in the 
art may construct a device and use the same in accordance with said 
principles and is to be regarded in no manner as restrictive of either the 
rights and privileges granted or of the scope of the intellectual property 
secured by granting of Letters Patent for which I hereby claim: