GB2604869A

GB2604869A - A sash window assembly

Info

Publication number: GB2604869A
Application number: GB2103530.8A
Authority: GB
Inventors: Talver Alexander
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-03-15
Filing date: 2021-03-15
Publication date: 2022-09-21
Also published as: GB202103530D0

Abstract

The sash window assembly 1 comprises a sash 15 slidable in a frame 11; a counterweight mechanism comprising a counterweight 25, a pulley wheel 20 and a chain 24 (optionally a rigid or push-pull chain) fixed to the sash and the counterweight and engaging teeth of the pulley wheel; and a drive mechanism comprising an electric motor 30 to rotate the pulley wheel and move the sash. The chain may comprise one end fixed to the sash and another fixed to the counterweight. The drive mechanism may comprise a shaft 22 extending from a lower to an upper portion of the frame, optionally connected to the pulley wheel via a worm drive. There may be a clutch to disengage the pulley wheel from the motor, e.g. by disengaging the worm drive. There may be a wireless controller and/or a sensor to close the sash in rain. The assembly is particularly suitable for an existing form of window, e.g. in a heritage building.

Description

A SASH WINDOW ASSEMBLY

FIELD OF THE INVENTION

The present invention relates to a sash window assembly.

BACKGROUND OF THE INVENTION

Sash window assemblies are well known, and typically comprise a sash that is moveable up or down within a frame to open or close the window. The sash includes the window glazing.

Many sash window assemblies include a cord connected to the sash, the cord going over a pulley and being connected to a counterweight. The counterweight balances most of the weight of the sash, making it easier to raise and lower. Sash windows typically have a counterweight and pulley system on both sides of the window and are manually operated. There have been attempts to motorise sash windows, however sash windows are heavy and prone to jamming in the frame, and past systems for motorisation have been unreliable and not widely adopted.

Sash windows are common in 'heritage_ buildings and so need to be preserved in their existing forms, but require significant effort to open and close, and are not user friendly by modern standards.

GB 2,283,055 A discloses a motorised sash window, in which the pulley at one side of the sash is driven by an electric motor to open and close the sash. The idea is that a motorised drive can be retrofitted to an existing sash window without impacting upon its aesthetics. However, the addition of a motor drive to the pulley makes the sash difficult to open and close manually, since this involves pulling the cord over the pulley whilst the pulley is held stationary by the motor. There is also a tendency for the motor to turn the pulley without the cord moving, for example if the sash becomes jammed or when it reaches the maximum extent of its possible range of motion.

It is therefore an object of the invention to provide an improved sash window assembly.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a sash window assembly comprising a sash, a frame in which the sash is slidable, a drive mechanism, and a counterweight mechanism, wherein the counterweight mechanism comprises a chain, a pulley wheel and a counterweight, wherein the sash and the counterweight are fixed to the chain and the chain engages teeth of the pulley wheel, and wherein the drive mechanism comprises an electric motor configured to rotate the pulley wheel and control a position of the sash within the frame.

Since the traditional cord is replaced by a chain, and the pulley wheel provided with teeth to engage the chain, the motor can be used to more positively drive the movement of the chain and overcome sticking or jamming of the sash in the frame, pulling the sash upwardly and lowering the counterweight. The chain may comprise one end fixed to a side edge of the sash, an opposite end fixed to the counterweight, and an intermediate portion that loops over and engages the teeth of the pulley wheel.

One of the problems with motorising the pulley wheel is that the sash still relies upon its own weight to move downwardly when the tension on the cord or the chain is released. This can leave the sash liable to jamming when the weight of the sash is not sufficient to overcome the friction between the sash and the frame. Sash frames are typically constructed from wood, which swells and reduces in accordance with the moisture content and temperature of the surrounding environment, and so jamming is common. Another factor that can prevent sashes from freely sliding in the frame is the addition of draft excluders between the sashes and the frame to improve thermal U-value ratings and sound proofing. Such draft excluders commonly include brushes extending from a beading strip, and the brushes add to the friction between the sashes and the frame.

A motorised pulley that continues to raise the counterweight without the sash lowering under its own weight may result in an excess of cord/chain between the pulley and the sash, which is liable to tangling around the pulley, and is also undesirable since the sash may quickly drop from height if the jammed sash suddenly releases from the frame.

Therefore, in a preferred embodiment the chain is of a type that is bendable in only one direction from a linear state, the direction of bending corresponding to the direction in which the chain bends around the pulley wheel. Such chains are generally known, and are sometimes referred to as rigid chains or push-pull chains. Since the chain is only bendable in one direction, it is unable to coil up between the pulley wheel and the sash, and so actively pushes the sash downwardly when the pulley wheel rotates. This results in a much safer form of motorisation where the sash will not suddenly drop from height if a jam between the sash and the frame releases.

Most of the space available at the top side of the frame may be taken up by the pulley wheel, and so the drive mechanism may comprise a drive shaft extending along the frame from a lower portion of the frame that has the electric motor to an upper portion of the frame that has the pulley wheel. Placing the motor at the lower portion of the frame where there is more space allows for a larger and stronger motor, and/or a larger and stronger gearbox.

Another problem with motorising sash windows is the risk of the window becoming jammed shut if the motorisation fails, or being un-openable to anyone without the ability to actuate the motorisation, for example if a remote controller for the window is lost or unavailable. These possibilities present an unacceptable fire risk in many situations, in which sash windows are relied upon as possible escape routes from the building. Therefore, the drive mechanism preferably comprises a clutch between the electric motor and the pulley wheel, wherein the clutch is actuable between engaged and disengaged states to control whether the pulley wheel is able to rotate independently from the motor. The clutch can therefore be disengaged to allow the sash to be moved manually, since the pulley can then turn freely of the motor.

Preferably, the clutch is manually actuable between the engaged and disengaged states by manually moving a button or lever. Then, if there is ever a need to open the window, this should always be possible manually.

In one embodiment, the drive shaft may comprise a worm gear adjacent the pulley wheel, the worm gear configured to engage teeth of a drive wheel that is rotatably connected to the pulley wheel. Then, disengaging the clutch may comprise moving the worm gear of the drive shaft out of engagement with the teeth of the drive wheel. Since the drive shaft runs for most of the height of the frame, the drive shaft is easy to flex by enough to disengage the worm gear from the teeth. This flexing may be accomplished using a lever or a button to push the drive shaft away from its normal, engaged, position.

Sash windows are easily jammed if one side of the sash is moved by more than an opposite side of the sash, for example if a person attempts to pull the left side of a sash upwardly but makes no efforts to lift the right side as well.

Therefore, the counterweight mechanism may be located within a first side of the frame and the sash window assembly may further comprises a further counterweight mechanism located within a second side of the frame opposite from the first side, the further counterweight mechanism comprising a further chain, a further pulley wheel and a further counterweight, wherein the sash and the further counterweight are fixed to the further chain and the further chain engages teeth of the further pulley wheel, and wherein the drive mechanism is configured to rotate both the pulley wheel and the further pulley wheel in synchronism with one another. This smooths the motion of the sash and makes jamming much less likely to Occur.

The drive mechanism may comprise a lower drive shaft extending from the first side to the second side of the frame and configured to transmit rotational motion between the pulley wheel and the further pulley wheel to keep the pulley wheels in synchronism with one another. Preferably the lower drive shaft extends horizontally along the lower part of the frame, and connects between the vertical drive shafts extending up to the pulley wheels at the opposing sides of the frame. The lower drive shaft is preferably flexible to allow for direct connections to the vertical drive shafts at the sides of the frame, however CV joints could altematively be used if desired.

The sash window assembly may include a controller connected to the drive mechanism, wherein the controller is configured to control the electric motor based on user input signals. The user input signals may be supplied using a control pad fitted to the frame of the sash window assembly, or may be supplied wirelessly, for example via Bluetooth (RTM) under control of a mobile phone app. Accordingly, the controller preferably comprises a wireless receiver for receiving wireless signals instructing movement of the sash within the frame.

Aside from user instructions, one situation in which it is desirable to close the sash window is during rain. Therefore, the sash window assembly may comprise a rain sensor connected to the controller, wherein the controller is configured to close the sash when rain is detected. The rain sensor may be positioned on a lower surface of the frame adjacent a lowermost surface of the sash, at the exterior side of the frame, for maximum effectiveness.

Although the sash window assembly could comprise only one movable sash, the assembly preferably comprises an additional one of the sash, the drive mechanism and the counterweight mechanism, so the sashes can be used in tandem with one another.

DETAILED DESCRIPTION

E mbodiments of the invention will now be described by way of non-limiting example only and with reference to the accompanying drawings, in which: Fig. 1 shows a schematic diagram of a sash window assembly according to an embodiment of the invention; Fig, 2 shows a schematic diagram of an electric drive unit of the embodiment of F ig. 1; Fig. 3 shows a schematic diagram of a counterweight mechanism of the embodiment of F ig. 1; Fig. 4 shows another schematic diagram of the counterweight mechanism of the embodiment of Fig. 1; Fig. 5 shows a schematic diagram of a pulley wheel forming part of the counterweight mechanism of the embodiment of Fig. 1; Fig. 6 shows another schematic diagram of the pulley wheel forming part of the counterweight mechanism of the embodiment of Fig. 1; Fig. 7 shows a schematic diagram of a clutch mechanism that may be implemented in the embodiment of Fig. 1; Fig. 8 shows another schematic diagram of the clutch mechanism that may be implemented in the embodiment of Fig. 1; Fig. 9a and 9b shows schematic diagrams of a lever mechanism for actuating the clutch mechanism of Figs 7 and 8; Fig. 10 shows a schematic diagram of another clutch mechanism that may be implemented in the embodiment of Fig. 1; and Fig. 11 shows a schematic diagram of a rain sensor that may be implemented in the embodiment of Fig. 1.

The figures are not to scale, and same or similar reference signs denote same or similar features.

The schematic diagram of Fig. 1 shows a sash window assembly 1 comprising a frame 10, an upper sash 15 and a lower sash 16. The sashes 15 and 16 are slidable up and down within the frame 10, with the sashes slightly offset from one another in a depth direction to allow this. The frame 10 comprises an upper portion 11, a left side portion 12, and right side portion 13, and a lower portion 14. The left and right side portions each house an arrangement of pulleys and counterweights to compensate for the weights of the sashes. The sash 15 is connected to two counterweights 25, one on each side of the sash, and the sash 16 is connected to counterweights 26, one of each side of the sash. Each counterweight is connected to the corresponding side of the sash by a respective chain 24, via a respective pulley wheel 20.

The rotation of each pulley wheel is driven by a drive shaft 22, which extends along the side portion 12 or 13, from adjacent the top portion 11 to adjacent the bottom portion 14. The right side portion 13 houses an electric drive unit 30 adjacent the bottom portion 14. The electric drive unit 30 is connected to the drive shafts 22 in the right side portion, and controls the rotation of the pulleys 20 and the raising and lowering of the sashes 15 and 16. Each drive shaft 22 in the left side portion 12 is connected to the corresponding drive shaft 22 in the right side portion 13 by a flexible drive shaft 27, which ensures the drive shafts 22 both rotate in synchronism with one another and so raise/lower the opposite sides of the corresponding sash in step with one another to help avoid jamming.

The flexible drive shaft 27 runs substantially straight along the lower portion 14 of the frame, and flexes upwardly through 90 degrees at both ends to connect to the drive shaft 22 at the left side portion 12 at junction 28, and to connect to the drive shaft 22 at the right side portion 13 at the electric drive unit 30. It will be appreciated that there are two flexible draft shafts 27, one for the drive shafts 22 that control the upper sash and one for the drive shafts 22 that control the lower sash.

In an alternative embodiment continuous-velocity (CV) joints could be used at the ends of the drive shaft 27 instead of the flexible portions to accomplish the 90 degree change in the rotational axis.

The schematic diagram of Fig. 2 shows a view of the electric drive unit 30, taken from above the electric drive unit The electric drive unit comprises two motors 31 and 32, the motor 31 controlling the raising and lowering of the sash 15 and the motor 32 controlling the raising and lowering of the sash 16. As shown, each motor may have an output shaft fitted with a worm gear 33, and each drive shaft 22 of the right side portion 13 may be fitted with a toothed wheel 34 that cooperates with the corresponding worm gear 33. Thus, rotation of each motor output shaft causes rotation of the corresponding drive shaft 22 at the right side portion 13, and also the corresponding drive shaft 22 at the left side via the corresponding flexible drive shaft 27.

As shown in Fig. 2, the electric drive unit 30 is housed inside of the right side portion 13 of the frame. The sash 15 comprises a frame holding a window glazing 15a, and the sash 16 comprises a frame holding a window glazing 16a. The frames of the sashes are located within tracks defined by the left and right sides portions 12 and 13 of the frame 10. One or more draft excluders 60 may be aligned along the side portions of the frame, between the sash and the frame. Each draft excluder is in the form of a long and thin strip with brushes extending from the strip and bridging the gap between the sash and the frame.

The schematic diagram of Fig. 3 shows a view of the sash window assembly taken looking in from the right side of Fig. 1. Accordingly, both drive shafts 22 in the right side portion 13 of the frame are visible, one for controlling the upper sash 15 and one for controlling the lower sash 16. The drive shafts 22 are both fitted with a worm gear 23 at the upper ends of the drive shafts, the worm gears 23 for transmitting rotational motion towards the pulley wheels 20. A counterweight mechanism of the sash window assembly may comprise the pulley wheels 20, chains 24 and counterweights 25 and 26. A drive mechanism of the sash window assembly may comprise the worm gears 23, drive shafts 22 and 27, and electric drive unit 30.

Fig. 4 shows a more detailed view of the counterweight mechanism, taken from the same direction as in Fig. 1, in which the pulley wheel for the upper sash 15 is visible. As shown, the chain 24 comprises a first end 24a that is fixed to the sash 15, and a second end 24b that is fixed to the counterweight 25. An intermediate portion of the chain 24 passes over the pulley wheel 20, and engages with teeth 20a of the pulley wheel to ensure the chain cannot slip over the pulley wheel 20.

It will be appreciated that as the sash 15 is lowered by rotating the pulley wheel 20 counter-clockwise, the counterweight 25 will be raised. Should the sash 15 become jammed and unable to move downward under its own weight, the chain 24 will be under compression between the end 24a and the pulley wheel 20 as the pulley wheel rotates anticlockwise. The chain 24a is only bendable in one direction from a linear state, which corresponds to the direction required to bend around the pulley wheel 20. The chain 24 cannot bend in the opposite direction to that which it bends in when it goes around the pulley wheel 20, due to secondary plates 24d that abut against primary plates 24c to prevent such bending. Therefore, the chain 24 actively forces the sash 15 downwards to overcome any sticking of the sash in the frame, without the chain becoming bent or tangled.

Fig. 5 and Fig. 6 show more detailed views of how the pulley wheel 20 may be driven to rotate by the drive shaft 22. The pulley wheel 20 is fixed to a shaft 29, and a first drive wheel 28 is also fixed to the shaft 29 and is rotationally stationary relative to the pulley wheel 20. The first drive wheel 28 has teeth which engage with teeth of a second drive wheel 27. The teeth of the second drive wheel 27 engage with the worm gear 23. The second drive wheel 27 has less teeth than the first drive wheel 28 and so the first and second drive wheels increase the torque that can be exerted on the pulley wheel 20 from the drive shaft 22.

The drive mechanism that transmits the rotational motion from each motor to the corresponding the pulley wheels 20 may comprise a clutch mechanism which can be disengaged to allow the pulley wheel to rotate freely from the motor. One possible clutch mechanism 41 is shown in Figs. 7 and 8, in which the drive shaft 22 is connected to a push rod 40, the push rod configured to move the drive shaft perpendicular to its axis to engage or disengage the worm gear 23 from the second drive wheel 27.

The push rod 40 may be connected to the drive shaft 22 at the distal end of the drive shaft 22, and the position of the push rod 40 may be controlled by a lever 45 that is manually actuable by a user. The push rod 40 has a plate 42 and a spring 43 is arranged between the plate 42 and a cam surface 47 of the lever to help keep the lever in whichever position it is moved to. Fig. 7 shows the lever 45 in a normal position aligned against the frame of the sash window assembly, in which the clutch is engaged and the motor can drive the pulley wheel. Fig. 8 shows the lever in an actuated position when a user has grasped the lever and pulled it outwardly from the frame, thereby disengaging the clutch by moving the worm gear 23 away from the second drive wheel 27, and allowing the pulley wheel to rotate independently from the worm gear 23.

The schematic diagrams of Fig. 9a and 9b show enlarged views of the lever 45 and how it fits into the frame 13 of the sash window assembly. The frame 13 has a cavity 13a with a slot 13b, and a proximal end of the lever has a pin 46 that is movable along the slot 13b and that is connected to the push rod 40 at a perpendicular angle. The proximal end of the lever has the cam surface 47 that controls movement of the push rod 40 in an axial direction of the push rod, based on the angle that the lever is held at.

A similar clutch arrangement may also be applied to the connections between the other drive shafts and pulley wheels. Many other alternate types of clutch mechanism are also possible, for example the second drive wheel 27 could be moved out of engagement with the first drive wheel 28, or the first drive wheel 28 could be moved axially along the shaft 29 to disengage from the second drive wheel 27. It would also be possible to use a flexible drive shaft similar to the drive shaft 27 to attach to the pulley wheel 20 and so avoid the need for the worm gear 23, allowing the clutch mechanism to be placed at the electric drive unit 30.

Another possible clutch mechanism is shown in Fig. 10, which is similar to the clutch mechanism of Figs 7 to 9b, but uses a push button 48 to control the push rod 40 instead of the lever 45. A push button implementation would have an advantage in that there would be no lever protruding into the area of the window when the clutch was disengaged, and so no risk of a lever catching on user clothing or otherwise hindering a user in exiting through the window.

The sash window assembly may comprise a rain sensor 50, as shown in Fig. 11. The rain sensor 50 is placed at the exterior of the sash window assembly, on a top surface of the lower portion 14 of the frame. The rain sensor 50 is vvirelessly connected to the controller 33, and when rain is detected the rain sensor will send a signal to the controller 33, causing the controller 33 to move the sashes to close the window and prevent entry of rain into the building.

Many other variations of the described embodiments falling within the scope of the invention will be apparent to those skilled in the art.

Claims

CLAIMS1. A sash window assembly comprising a sash, a frame in which the sash is slidable, a drive mechanism, and a counterweight mechanism, wherein the counterweight mechanism comprises a chain, a pulley wheel and a counterweight, wherein the sash and the counterweight are fixed to the chain and the chain engages teeth of the pulley wheel, and wherein the drive mechanism comprises an electric motor configured to rotate the pulley wheel and control a position of the sash within the frame.
2. The sash window assembly of claim 1, wherein the chain is of a type that is bendable in only one direction from a linear state, the direction of bending corresponding to a direction in which the chain bends around the pulley wheel.
3. The sash window assembly of claim 1 or 2, wherein the chain comprises one end fixed to a side edge of the sash, an opposite end fixed to the counterweight and an intermediate portion that loops over and engages the teeth of the pulley wheel.
4. The sash window assembly of claim 1, 2 or 3, wherein the drive mechanism comprises a drive shaft extending along the frame from a lower portion of the frame that has the electric motor to an upper portion of the frame that has the pulley wheel.
5. The sash window assembly of claim 4, wherein the drive shaft comprises a worm gear adjacent the pulley wheel, the worm gear configured to engage teeth of a drive wheel that is rotatably connected to the pulley wheel.
6. The sash window assembly of any preceding claim, wherein the drive mechanism comprises a clutch between the electric motor and the pulley wheel, wherein the clutch is actuable between engaged and disengaged states to control whether the pulley wheel is able to rotate independently from the motor.
7. The sash window assembly of claim 6, wherein the clutch is manually actuable between the engaged and disengaged states by manually moving a button or lever.
8. The sash window assembly of claims 6 or], when dependent on claim 5, wherein actuating the clutch comprises moving the worm gear of the drive shaft in and out of engagement with the teeth of the drive wheel.
9. The sash window assembly of any preceding claim, wherein the counterweight mechanism is located within a first side of the frame and the sash window assembly further comprises a further counterweight mechanism located within a second side of the frame opposite from the first side, the further counterweight mechanism comprising a further chain, a further pulley wheel and a further counterweight, wherein the sash and the further counterweight are fixed to the further chain and the further chain engages teeth of the further pulley wheel, and wherein the drive mechanism is configured to rotate both the pulley wheel and the further pulley wheel in synchronism with one another.
10. The sash window assembly of claim 9, wherein the drive mechanism comprises a drive shaft extending from the first side to the second side of the frame and configured to transmit rotational motion between the pulley wheel and the further pulley wheel to keep the pulley wheels in synchronism with one another.
11. The sash window assembly of any preceding claim, further comprising a controller connected to the drive mechanism, wherein the controller is configured to control the electric motor based on user input signals.
12. The sash window assembly of claim 11, wherein the controller comprises a wireless receiver for receiving wireless signals instructing movement of the sash within the frame.
13. The sash window assembly of claim 11 or 12, further comprising a rain sensor connected to the controller, wherein the controller is configured to close the sash when rain is detected.
14. The sash window assembly of claim 13, wherein the rain sensor is positioned on a lower surface of the frame adjacent a lowermost surface of the sash.
15. The sash window assembly of any preceding claim, wherein the sash window assembly comprises an additional one of the sash, the drive mechanism and the counterweight mechanism.
16. The sash window assembly of any preceding claim, wherein the sash window assembly comprises one or more draft excluder strips positioned between the sash and the frame.