GB2414515A - Powered sash window - Google Patents

Abstract

The invention relates to a window having a frame and a sash 50 slideable in the frame, wherein movement of the sash is controlled by a pair of lead screws 35, 40 having travelling nuts 42, 44 fastened to opposed sides of the sash, and by a common drive 10 connected to the lead screws for bringing about simultaneous rotation of said lead screws to effect sliding of the sash. Apparatus to convert existing windows is also disclosed. The drive may be controlled by a local controller for the window including microcontroller means having a stored program having routines for effecting raising or lowering of the sash. There may further be provided a system controller communicable with the local controller e.g. by a hard-wired link or by a radio or bluetooth link and having a stored programme for communicating with a group of local controllers for controlling several windows in a house or flats.

Description

MPROVEMENTS IN OR RELATING TO SASH WINDOWS

FIELD OF THE INVENTION

This invention relates to sash windows in which at least one sash is slideable under the control of a mechanical drive for effecting sliding movement of the sash, and to mechanical drive apparatus for fitting to a sash window for effecting sliding movement as aforesaid. It also relates to a kit of parts for building into or for retro fitting into a window as aforesaid for effecting controlled sliding movement of at 0 least one slideable sash.

BACKGROUNI) TO THE, INVENTION Sash windows, including box sash windows have been in use in the UK and elsewhere for some hundreds of years. A short history ol' these windows, and many other details, are available from the website of The Original Box flash Undo Company, www.boxsash.com.

GB-A-8X7533 discloses a power-operated sash window in which movable upper and lower sashes are controlled by respective travelling nuts that run on respective lead screws in opposed sides of the frame. A pair of' motors in the lower member of the frame independently drive oppositely directed drive shafts that extend :. to opposite corners of the frame where the rotation of each shaft is transmitted to each lead screw by a pair of meshing bevel gears. A switch panel has controls for independently raising and lowering each sash. GEs- A-888715 discloses a similar lead screw arrangement for a sash window. 'he use of lead screws to raise and lower the sashes of a sash window is also disclosed in GRA-2242225 (Ireland).

Rack and pinion drives built into the frame sides of' sash windows are disclosed in US-A-3324594 (Hettinger), US-A-6343436 (Milano), GB-A-23] 8384, GB-A-2378218 and WO 03/012237.

SUMMARY OF THE INVENTION

The present invention relates to a system that provides a powered window opening and closing system and also to a system allowing for remote closing and locking of the windows. The system can also allow the user to close and lock all of the windows within the house via a remote control, leaving the house secure.

Conventionally, sash windows are opened and closed manually and when open are typically easy to open from the outside of the house by intruders. The lo present invention seeks to provide a system of both electrically and manually opening and closing windows and that locks the windows in any position at which the window stops. Additionally, the windows may also be closed centrally and/or remotely for the purposes of securing the property.

In one aspect the invention relates to a window having a frame and a sash slideable in the frame, wherein movement of the sash is controlled by a pair of lead screws having travelling nuts fastened to opposed sides of the sash, and by a common drive connected to the lead screws for bringing about simultaneous rotation of said lead screws to effect sliding of the sash.

:.: . The invention also relates to apparatus for fitting to a window having a frame and a sash slideable in the frame for effecting sliding movement of said sash within said frame, said apparatus comprising: a pair of lead screws for fitting into opposite sides of the frame, said lead screws having travelling nuts having fastening formations for fastening to opposed : . sides of the sash; and a common drive connected to the lead screws for bringing about simultaneous rotation of said lead screws to effect sliding of the sash. - 3

Both the sash window and the drive for effecting sash movement may, and usually will, be proved as kits of parts for on-site assembly. The invention further comprises kits of parts as aforesaid.

The invention further comprises a window having a frame and a sash slideable in the frame, wherein movement of the sash is controlled by a pair of lead screws having travelling nuts fastened to opposed sides of the sash, and by a common drive connected to the lead screws for bringing about simultaneous rotation of said lead screws to effect sliding of the sash, and wherein the drive is controlled by a local lo controller t'or the window including microcontroller means having a stored program having routines for effecting raising or lowering of the sash. There may further be provided a system controller communicable with the local controller e. g. by a hard wired link or by a radio or bluetooth link and having a stored programme for communicating with a group of local controllers for controlling several windows in a house or flats.

BRIEF DESCRIPTION OF THE DRAWINGS

I low the invention may be put into effect will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic perspective view of a sash forming part of a sash :, window and associated apparatus for raising and lowering the sash relative to a frame of the window; Fig. 2 is a diagrammatic perspective view of a motor, gearbox and associated components forming part ol'the apparatus of Fig. 1; Fig. 3 is an underside perspective view of a sash window having fitted thereto the apparatus of Fig. 1; and Fig 4 is a fragmentary perspective view of a sill region of a sash window having the apparatus of Fig. I fitted thereto. - 4

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

In Fig. I apparatus is shown for raising and lowering a sash 50 relative to the frame of a box sash window. A motor 10 carried in mounting frame 12 is mounted to s the underside of the sill via l'ixing holes provided in the mounting bracket. The motor is advantageously positioned with its drive shaft directed horizontally due to space limitations under the sill and to avoid unsightly components appearing beneath the sill. Its output shaft drives T-gearbox 16 by means of reduction gearing 14 in the form of a pinion and spur gear. I; irst and second drive shal'ts 18, 20 connected to the 0 T-gearbox 16 extend along the underside of the sill to adjacent the corners of the frame where they are supported by bearings 22, 24 carried in brackets secured to the underside of the frame. The drive shafts 18, 20 terminate at bevel gears 26, 30 that mesh with bevel gears 28, 32 of lead screws 38, 40 that are directed parallel to and fit within the sides of the frame, straight cut gears with a 1: I ratio being the most cost ei'i'ective. Bevel gears available in steel, brass or polyacetal which is a polymer oi'a low coefficient of friction and high resistance to wear. Gears made from polyacetal are also quieter, smoother running and cheaper than steel or brass gears. The lead screws are supported by bearings, including lower thrust bearings 34, 36 that provide support for the lead screws and any downward load from the sash 50. Follower nuts 42,44 fit movably onto the lead screws and are connected to the base of the sash 50 at

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opposed sides as shown. For that purpose each nut 42, 44 is formed with a web plate 46 whole plane is directed normally away from the axis of the lead screw and which : . terminates at a fixing plate 48 whose plane is parallel to the axis of the lead screw and which is provided with fixing holes for screw or other attachment to the sides of 2s the sash 50. As can be seen in Fig 1, the material oi'the sash 50 is rebated to form 4 sockets for receiving the fixing plates 48 whose surface then coincides with the side surface of the sash so that the distance between the sides of the sash and the frame is minimised and there is little opportunity for draughts. The T-box 16 is driven from a single input shaft and has two meshing bevel gears so that its output shafts rotate in opposite directions. '['his means that the lead screws 38, 40 will be revolving in the same direction and will use the same thread patterns so that the sash 50 is being driven in the same direction on both sides A frequent problem with conventional sash windows is judder, which occurs s when each side of the sash 50 is raised or lowered at different rates. Either the sash jams completely or it judders violently as it rubs against the frame. IIowever, in the present arrangement, the sash 50 is driven simultaneously from both sides via lead screws 38, 40 and always at the same rate because of the common T-gearbox 16 so that the sash action may be made smoother with judder reduced or eliminated.

lo Furthermore, conventional sash windows have a poor locking mechanism, which is not usually an integral part of the window structure and is typically bolts or a clasp attached to the frame that can only lock the sash in the fully closed position. The new sash window is effectively always locked because of the non-reversing action of the lead screws 38, 40 that drive the sash 50 up and down. The sash 50 cannot be forced up or down manually without breaking the lead screw and follower nut mechanism which is relatively strong, and the only way the windows will raise or lower is by operation of the drive mechanism provided. This allows the windows to be safely left open 10 - 80mm for ventilation, with a relatively slight and acceptable risk of the window being forced open any further. This increase in security does not come with a compromise in style since traditional sash windows use large boxes either side of the window to house counterbalance weights for the sashes. The same boxes can be used to house the lead screws 38, 40 and if desired also other mechanical and electronic : . components of the system. Advantageously the counterbalance weights are still connected to the sashes to minimise the frictional forces between the traveller nuts 2s 42, 44 and the lead screws 38, 40 and hence the driving forces needed to raise or lower the sash 50.

The force required to raise or lower a sash of a conventional box sash window has been measured as being about 30 N. but frictional forces opposing movement may be increased by judder and by the effects of old paint on the window. In a new or renovated window operated by a mechanism ol'the present kind, it is estimated - 6 - that the force required may be about ION but an assumed value of 30N provides a safety factor and a margin for loss of performance over time. Assuming that the lead screws 38, 40 are required to move a force of 30N up and down over a distance of 700mm at a speed of between 0.08 and 0.06 m/s, the lead should be between 2 and 8mm. Lead screws come in different qualities from low end rolled units to high precision ground and milled threads. The present apparatus does not require a precision motion so the quality of the lead screw is not of high importance. A standard rolled lead screw with an accuracy of +/-0. 5mm with a single start would be satisfactory and would be relatively inexpensive. A 20mm diameter screw having a lo root diameter of 14.9 mm, a maximum length of 746mm and a 4mm lead would need revolutions to move the sash 700mm which is considered satisfactory. Because of the location of the lead screws 38, 40 within the *ame, it is likely that they and their associated components will be affected by moisture so that they should be of corrosion resistant material, either an alloy or treated steel.

The values below are only examples. Each window, if custom fitted, would be of different dimensions and would require a different driving force. Counterbalances may not be required for many window constructions, in which case the mechanical system bears the full weight of the sash.

The maximum load for the lead screw using 4140 alloy steel and a follower nut 42 ol' low-friction plastics material e.g. polyacetal or HDPF, or preferably : I' aluminium was calculated, on the assumption that a lubricant is also applied. For a 720mm long 20 X 4 alloy lead screw, the maximum column load is 9196N, which 2s gives a safety t'actor of nine over the estimated force that will be exerted on the frame during a break-in. The force needed to lift the Sash is assumed to be 30N. The torque needed to lift IN = 1.3242 x 10-3 Nm for the above lead screw, so that the torque needed to lilt 30N is 0.04Nm and the motor 110 will desirably provide at least this torque. If the shafts and lead screws operate at an RPM of 1050 it can fully open or close the window within 10 seconds. A typical small 12V electric motor (Igarashi N3657-145-GF-3) having a torque at maximum efficiency of about 18Nm and - 7 - connected via reduction gearing 14 having a 3:1 ratio can produce a torque of 54Nm, which is acceptable, so that it is feasible to raise and lower a sash of a sash window using a mechanism based twin lead screws within an acceptable time and using readily available small DC or AC electrical motors. s

The system needs to be manually overridden by hand in case of power failure or emergency. The override may be via a spur gear meshing with the drive gear on the T-box, the override shaft then protruding from the front of the frame below the sill. A handle can then be attached to this shaft to manually wind the system. The lo gearing on the override system self-evidently needs to be more than 1:1, otherwise the user would be winding the handle for a long time before the window opened or shut. The ratio could be more than 1:1 up to say I:S so that the window would open at a decent rate and still with ease. The way the opening and closing mechanism has been designed should mean that the force required is minimal. In theory the only resistance the mechanism produces is friction, since the sash 50 is counterbalanced by the pulleys and weights. Fig 2 shows the gear train is arranged, with a pinion 51 on the output shaft of motor 10 meshing with the spur gear 52 on the input shaft of T gearbox 16. When the handle is turned, the large override spur gear meshes with the spur on the T-box and manually drives the system. An override spur 56 on shaft 44 is in permanent mesh with spur gear 52, so that shaft 54 will always be spinning when the system is in operation. The override shaft 54 should therefore not protrude from the frame and should be concealed beneath the sill. The override system will only be : ', operational when handle 58 is attached to the override shal't 54, onto which it is a push fit. When the handle is turned the large spur gear 56 imparts rotation to the 2s smaller spur gear 52 e.g. at a velocity ratio of about I:3. The override handle will . require about 60 revolutions to either full open or fully close the window at a torque of 0.2Nm.

If a customer chooses not to use counterbalance weights for the sash, the force to drive the window open would increase significantly so that a different gearbox ratio needs to be selected. With the new gearbox, the force needed to turn the handle - 8 - will be reduced, but the number of rotations required will be approximately doubled.

In this ease, a battery backup system may be offered, where the system includes an alternate power source. A backup battery is fitted in each frame and is trickle-charged by the mains power supply. In the case of a power cut the system can operate solely s on the backup battery supply, thus removing the need for a manual override mechanism.

Fig. 3 shows the present mechanism fitted to a box sash window of size e. g. 1700 mm x 1000 mm with a single hung sliding sash, which is typical of sash lo windows used in the UK. However, the mechanism can easily be configured to fit frames of different size. The motor, mounting bracket 12, drive shafts 18,20 are seen mounted below and attached to the sill 44, and the lead screw 38 and associated components including lower bearing 34 and upper bearing 34a fit within the side box 46 of the frame (the weights and cords being omitted for the sake of clarity). In Fig. 4 is the sill 44 it seen with the handle 58 fitted, but the working components of the present drive mechanism are substantially concealed, and the normal sash window appearance is preserved.

The present window may be controlled by a local switch panel having an up and a down-switch for supplying power to motor 10 to drive the motor in an appropriate direction. Additionally, the windows may also be closed centrally and/or b remotely for the purposes of securing the property to which the present window is 2 fitted. The system may comprise two separate circuits, and controllers. 'I'he first is a central controller for handling all of the remotely activated commands and also notifies the user of any errors. The second or local controller is located in each b window and is for controlling the regular operation of the window, the identification of an obstruction, and recognition of the open/closed the state of the window. Both the centrla and the local controllers may be based on the same microcontroller e.g. a PIC16C505 microcontroller which is a 14-pin 8- bit microcontroller with 11 I/O pins.

The microcontroller features ICSP, an outboard oscillator timer and a power saving sleep mode. - 9 -

The main controller typically, but not exclusively, comprises a receiver, a microcontroller, an alarm circuit, a power supply, error LED's for monitoring the state of each window, or e.g. the state of the windows on each floor, a reset button, a s control button e.g. for closing ground floor windows, and a control button for closing all windows including in the case of a house the ground floor windows and upper windows. The operation of the main controller is typically but not exclusively as follows: I. Wait for a signal from the receiver or from the control panel.

o 2. Send a signal to either just the downstairs windows or all the windows, depending on the signal received.

3. If an error is fed back, indicate on which floor the error is located and sound an alarm until the system is reset.

It may be made highly secure by incorporating a rolling code feature, which makes the control signal dil'ficult for an unauthorized person to crack. Furthermore if the control unit or an external control transmitter for it (e.g. a keyfob controller) should Hall into unauthorized hands, it would still not be possible to effect opening of the windows since the central unit only responds to CLOSE commands and not to OPEN commands, so that the windows cannot be opened from the exterior of the building by remote control.

I'he window controller typically, but not exclusively, consists of two push buttons (up and down commands), a microcontroller, a motor controller, a current sensor, a motor power supply circuit, an error LED circuit, and a microswitch and monitoring circuit, the state of the microswitch indicating whether the window is open or closed. It may be connected to the main controller by a control loom which . r carries power, command signals and error signals. The window controller may, by way of example, be mains or battery operated and the power required to operate the windows may also be supplied from the window controller from its own power supply or an independent source. The operation of the window controller is typically but not exclusively as follows; - 10 1. Wait for a signal from the main controller or from one of the windows' regular operation buttons.

2. If a signal from the main controller is received then check that the window is not already shut, if it is do nothing, if it is open drive the motor s until the window closes, or until there is a current overload, indicating an obstruction and send an error signal back to the main controller.

3. If a signal l'rom the window's own control panel is received, check that the window is not already shut and either open or close the window, until the window is fully shut, has come across an obstruction or until the button 0 has been released.

A locally stored programme within the local microcontroller typically sits and waits until it receives a signal on any of its inputs. By way of example, this could be; 1. The Main Controller telling it to shut the window.

2. 'I'he UP button telling it to raise the window.

3. The DOWN button telling it to lower the window.

4. An error coming from the Current Switch.

For remote operation, for example, the remote control unit is triggered e. g. using a keyfob remote or from a further station that can be used to remotely secure the property and transmits a signal to shut the windows. The local control unit detects the signal telling it to shut the window. The program enters into a subroutine SlIU'I', where it first checks that the signal is still there, the main controller outputting the signal for typically 0.5 of a second,. If'the control signal does not continue for a sufficient time the local controller sees this as a false signal and goes back to the main part of its stored program and continues checking the inputs. If the signal is still there it will begin driving the motor to shut the window and will then check the current switch. If the current is high, the controller knows that the motor is drawing too much current and the mechanism may be jammed or obstructed. The controller : ,, will stop the motor and send an error signal back to the main controller and an LIED . will be illuminated within the DOWN button on the windows control panel, indicating to the user that there is a problem in the window. The program will remain - 11 inoperative until the system is reset by pushing the DOWN button. If the local controller does not detect anything on the current switch it will continuously check the micro switch. If the switch is shut the controller will know that the window is already closed and will Call back into the main program.

If the local controller detects either the Up or Down button being pressed it will l'all into the relevant subroutine which are essentially the same apart from that one makes the window go up, the other makes the window go down. The subroutine will make the controller check the signal again to check if it is still there and not just l o a false signal. If it is a false signal it will drop out of the subroutine and fall back into the main program. If the signal is still there it will begin driving the motor up or down, until either the micro switch is switched, the current Switch is switched or the button is released.

For local operation, non-latching pushbutton switches are used to operate the windows. The window will open or close while the button is pressed, as soon as the button is released, the window will stop moving. For security reasons, the pushbuttons are not located on the window itself As previously explained, the drive action of the lead screws is non reversible, the sash cannot be raised or lowered by hand. This makes the window locked from the outside in any position. The user may choose to leave the window open 10 - 30mm for ventilation, Prom the outside, an intruder would not be able to lift the sash any further to gain entry to the property, this is the security advantage of this design. However, il' the pushbuttons were located . . :,:, on the frame, the intruder may be able reach the buttons and activate the system and open the window. For this reason, the pushbuttons are located away from the l'rame.

Means may be provided for shutting down the drive motor for the window sash in the event of an obstruction in the sash opening or closure path. A current : A, monitoring circuit (not shown) will signal to the microcontroller if the motor is drawing an unusual amount of current, and the microcontroller may then stop the motor. The motor will be driven by a motor driver e.g a full-bridge L6202 motor driver available from S(iS_Thomson.

Using the apparatus of the invention, an increase in security can be obtained s without compromise in style, and a house may be made secure in e.g. about 10 seconds remotely by pressing a single button on a keyfob remote control. In one embodiment, every window is automatically controlled, in another embodiment only the downstairs windows are controlled and in a third embodiment the central controller has first and second channels, one lor the upstairs windows and the other l o for the downstairs windows.

It will be apparent that modifications may be made to the embodiment described above. For example, the present apparatus may be fitted to a Irame having upper and lower sliding sashes. In that case the present mechanism may be duplicated, one pair of lead screws controlling the upper sash, and a second independently driven pair of lead screws driving the lower sash. : - 13

Claims (21)

1. A window having a frame and a sash slideable in the frame, wherein movement of the sash is controlled by a pair of lead screws having travelling nuts fastened to opposed sides of the sash, and by a common drive connected to the lead screws for bringing' about simultaneous rotation of said lead screws to el'f'ect sliding ofthe sash.

2. The window of claim 1, wherein weights in side boxes of the t'rame provide lo counterbalance for the sash.

3. The window of claim I or 2, wherein a gearbox mounted under a sill of the frame has l'irst and second output shafts connected to said lead screws via first and second pairs of bevel gears in corners of the frame.

4. The window of claim 3, wherein the motor is connected to the gearbox via reduction gearing.

5. The window of claim 5, wherein said reduction gearing has a velocity ratio of about 3:1.

6. The window of claim 3, 4 or 5, further comprising manual drive means connected to an input shaft of the motor to permit sliding of the sash to be effected by :.: .. hand. * 2s .

7. The window of claim 6, wherein the manual drive means is connected to the input shaft by step-up gearing having a velocity ratio of more than 1:1 to 5: 1. :

: , ,

8. 'I'he window of any preceding claim, wherein the drive is controlled by a local controller for the window including microcontroller means having a stored program having routines for effecting raising or lowering of the sash. - 14

9. The window of claim 8, wherein the local controlled is controlled by a system controller having a stored program for simultaneous control of a group of windows.

10. A motorised sash window substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

I]. Apparatus for fitting to a window having a frame and a sash slideable in the frame for effecting sliding movement of said sash within said frame, said apparatus o comprising: a pair of lead screws l'or fitting into opposite sides of the frame, said lead screws having travelling nuts having fastening formations for fastening to opposed sides of the sash; and a common drive connected to the lead screws for bringing about simultaneous rotation of said lead screws to effect sliding of the sash.

12. The apparatus of claim 11, wherein said common drive includes a gearbox for mounting under a sill of the frame, said gearbox having first and second output shafts for connected to said lead screws via first and second pairs ol' bevel gears to be located in corners of the frame.

13. The apparatus of claim I 2, wherein the motor is connected to the gearbox via reduction gearing.

14. The apparatus of claim 13, wherein said reduction gearing has a velocity ratio of about 3:1.

15. The apparatus of claim 12, 13 or 14, further comprising manual drive means connected to an input shaft of the motor to permit sliding of the sash to be effected by so hand. -

16. The apparatus of claim 15, wherein the manual drive means is connected to the input shaft by step-up gearing having a velocity ratio of more than 1:1 to 5:1.

17. The apparatus of any of claims I I -16, further comprising a local controller for a window including microcontroller means having a stored program having routines for effecting raising or lowering of a window sash.

18. The apparatus of claim 17, further comprising a system controller communicable with one or more local controllers having a stored program for lo simultaneous control of a group of windows.

19. The apparatus of claim 18, further comprising a keyfob remote or other remote signalling device for signalling the system controller to effect sash closure and/or remote securing of the property.

20. Apparatus for fitting to a window having a frame and a sash slideable in the l'rame for effecting sliding movement of said sash within said frame, said apparatus being substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

21. 1Y kit of parts for making, or for fitting at least one sash drive to, a window as claimed in any of claims 1-10.

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