Balance spring locking slide block for tilt-out windows

The invention relates to tilt-out window assemblies in which a window sash may be rotated from its normal vertical position causing a slide block connected to a spring balance assembly to be locked into place to prevent release of the spring balance assembly on tilting or removal of the window sash from the window frame. The slide block rides in the jamb channel in which the window sash normally slides up and down and incorporates a rotatable locking cam. The locking cam is rotated on tilting of the window sash so as to force a set of locking members against the sides of the window frame jamb channel to engage the block into a fixed position in the channel. The window sash is operatively connected to the locking cam to provide rotation thereof to lock the slidable block. The window sash may be removed from the frame and from engagement with the locking cam if desired.

BACKGROUND 
This invention relates generally to tilt-out windows, both of the take-out 
and non-take-out type. It is particularly directed to those types which 
include metal (aluminum) or vinyl sash guides or jamb channels, most 
particularly the vinyl type. 
Rigid plastic extrusions are being used more frequently as side jamb 
channels in windows of this type. Vinyl is typically used and is preferred 
for this invention. Various types are well known. 
Generally, windows of this type have been in use for some time. They are 
typically provided in a pivoted or tilt-out double-hung version. Their 
convenience for washing the outside of the window or for replacing broken 
panes has made them very popular. 
The counterbalance system for holding such window sashes in an open or 
closed position has progressed from a counterweight to a spring balance 
assembly, various types of which are well known. The spring balance 
assembly is enclosed in the side jamb channels or weather strips on each 
side of the window sash. 
One of the problems with the pivoted or tilt-out windows has been the 
retention of the end of the counterbalance spring assembly which is 
attached to or removably secured to the window sash itself. Since the 
window sash can be tilted out of the frame, or is even completely 
removable in some designs, it is desirable that the sash not be vertically 
movable when tilted out or when its full weight is not available to offset 
the pull of the spring balance assembly. It is desirable when tilting the 
window or removing it that the spring balance assembly be retained in a 
fixed position within the jamb channel by a positive locking arrangement 
and that the spring assembly not be allowed to move or to snap upwardly in 
an uncontrolled manner as, after a few such releases, the assembly may be 
deformed and its effectiveness reduced. 
Many types of locking mechanisms have heretofore been available. Reference 
may be had to U.S. Pat. Nos. 4,364,199; 3,797,168; 3,844,066; 4,079,549; 
3,676,956; 3,055,062; 3,842,540; 3,524,282; 3,195,174; and advertising 
articles entitled Caldwell Aluma-Tilt Balance by Caldwell Manufacturing 
Co., P.O. Box 444, Rochester, N.Y. 14602 and Jim Walter Window Components, 
Series 9000 Balance/Weatherstrip for Full-Tilt Windows by J.W.W.C. 1009 
Algonquin/Sioux Falls, S.D. 57104. 
A still further type of locking mechanism comprises a hook which has a 
sharp point to embed into one of the walls of the side jamb channel. 
However, this type of locking engagement is subject to being dislodged 
when downward pressure is applied. 
SUMMARY OF THE INVENTION 
The invention is directed to a novel locking mechanism for spring-balance 
tilt-out windows. The locking mechanism comprises a slide block shaped to 
ride up and down in the side jamb channels and which incorporates a pair 
of oppositely disposed extendable locking members which are operated by a 
rotatable cam member operatively connected to the window sash so as to 
rotate on window tilt-out to extend the locking members outwardly of the 
block for engagement into the walls of the jamb channel to lock the block 
in a fixed position therein. Since the spring balance assembly is 
connected to the block it is maintained in position until the window is 
rotated back into its normal vertical position whereby the cam releases 
the block for movement.

DESCRIPTION OF PREFERRED EMBODIMENT 
FIG. 1 shows the environment of the present invention, omitting details of 
the frame, and the spring balancing mechanism, as well as other structural 
details which are considered conventional. As for balancing mechanisms, 
which may be used with the present invention, any conventional balancing 
mechanism will serve the purpose. Since windows are symmetrical in 
construction, it is believed necessary to describe only one-half thereof 
in detail. Consequently, only the details of one side of the window and 
one jamb track thereof are shown. 
The improved locking block or slide member of the invention is shown in 
connection with a double-hung tilt-out type window in FIG. 1. The frame of 
the window, indicated at 10 incorporates sashes 11 and 12 which are 
slidably mounted in jamb channels one of which is generally indicated at 
15. Such jamb channels are ordinarily parallel to one another in the frame 
and the individual sashes slide vertically therein between closed and open 
positions. Conventionally, each sash has a balance spring assembly (not 
shown) associated therewith on either side of the sash and carried in the 
respective jamb channel in which the sash slides. As shown in FIG. 1, the 
lower sash 12 is shown in a tilted position. With such tilt of the sash, 
the improved balance spring locking block or slide member operates to lock 
itself in a fixed position by embedding the serrated ends of the spring 
member into the jamb channels, one to each side of the sash, so as to 
maintain the balance spring assembly in a fixed position during removal of 
the sash from the jamb channels for cleaning, replacement and the like. 
The spring balance assembly is thus maintained in a fixed position so that 
it will not move in the jamb channel and the sash may be readily replaced, 
rotated into the vertical position to unlock the locking block or slide 
member so as to allow vertical movement of the window in the jamb channels 
very readily. 
A finger operated sliding guide or similar arrangement indicated at 13 
holds the window in position in the normal operating condition by engaging 
the track 16 (best seen in FIG. 7), as is conventional. 
As shown in FIG. 2, slide block 20, which slides vertically in jamb 
channels such as jamb channel 15, is of a generally rectangular shape 
having oppositely disposed sliding side surfaces 22 and 24, and upper head 
portion 26 and a lower enclosing bottom portion 28. Head portion 24 
preferably includes a metal head plate 25 to which a spring balance 
mechanism (not shown) is connected. The metal head plate 25 serves as a 
stiffener for slider block 20 and prevents distortion of its shape from 
the forces exerted by the balance mechanism. 
Slide block 20 is preferably made of a molded plastic material and is 
machined or otherwise smoothly finished on its sliding surfaces. 
Celcon.RTM. or Delrin.RTM. acetal plastic is preferred. Celcon.RTM. is a 
registered trademark of Celanese Chemical Co., New York, N.Y. Delrin.RTM. 
is a registered trademark of Hercules, Inc., Wilmington, Del. 
Slide block 20 also has a partial transverse base 30 with an open top, 
indicated at 32 for receiving rotatable locking cam 34 having a tab 36 
which passes through opening 32 and when cam 34 is rotated in base 30 
rises on its arcuate surface 33 to hold cam 34 in block 20 (best seen in 
FIG. 6). 
Locking cam 34 also includes oppositely disposed arcuate camming surfaces 
40 and 42 separated by straight, relieved surfaces 44 and 46 and a 
relatively large flat head portion 50. 
Head portion 50 acts to hold spring member 52 in position in the box-like 
enclosure 54 formed on the backside of slide block 20 (as shown with 
reference to FIG. 2). Enclosure 54 is formed by side members 22 and 24, 
bottom 28 and intermediate cross member 56. When locking cam 34 is 
inserted into base 30 with spring member 52 therebetween, the flat top of 
head 50 is flush with the edges of the members forming enclosure 54 to 
facilitate the fitting of slide block 20 into the jamb channel (best seen 
in FIG. 5). 
Spring member 52 as shown includes oppositely serated end portions 58 and 
69 which fit into slots 62 and 64, respectively to allow the extension 
(FIG. 3) and the retraction (FIG. 4) of serated ends 58 and 60 as the 
locking cam is rotated from the position shown in FIG. 4 to the position 
shown in FIG. 3. 
The operation of the locking slide block will be clearly understood by 
reference to the drawings in which it has been previously noted that the 
slide block 20 is normally freely slidable in its jamb channel when the 
window sash to which it is operatively connected is in its normal vertical 
position. Upon the disengaging of sliding guide lock 13, the window sash 
is permitted to be tilted out to the pivoted position shown in FIG. 1. The 
movement of the sash is transmitted through a connecting pin (not shown) 
extending from the window sash into the conforming opening 63 in cam 
member 34 its connection to the rotary cam member 34 causing it to extend 
locking members 58 and 60 to be forced into the walls of jamb channel 15 
thus holding the slide block in a locked position. 
While the invention has been described with reference to certain features, 
structure and material, various modifications may be made without 
departing from the principle and scope of this invention as defined in the 
following claims.