Retractable awning

Abstract

A retractable awning. The retractable awning may include a screen that may be extended and retracted, a first motor arranged to extend the screen, a second motor arranged to retract the screen, and a control unit arranged to control the first motors and the second motor.

Description

RELATED APPLICATIONS[0001]The present application is a continuation of U.S. patent application Ser. No. 12 / 525,684, filed in the United States on Aug. 4, 2009, now allowed. U.S. patent application Ser. No. 12 / 525,684 is incorporated by reference herein in full.TECHNICAL FIELD[0002]The present invention relates to a retractable covering apparatus such as a canopy or awning, having a control unit for controlling the extension and retraction thereof. The invention also extends to a control system for such an apparatus, and a method for operating a covering apparatus.BACKGROUND OF THE INVENTION[0003]Awnings or canopies are often used for example outside restaurants or in private gardens to cover open areas and provide shelter for the people underneath them, thereby providing sun protection, rain protection or the like. A variety of covering apparatuses are known in the art. For example some canopies are provided on the side of a building, with folding arms which can be extended out from...

AI Technical Summary

Benefits of technology

[0012]Although the non-driving motor could be allowed to free-wheel, preferably both motors remain engaged during extension and retraction. In this way they may be controlled to prevent sagging of the screen during extension or retraction. Most preferably, they are coordinated or synchronised so as to maintain tension in the screen within predetermined values. This may be achieved by controlling the motors such that a predetermined degree of stretch is applied to the screen. By coordinated or synchronised, we mean that the motors are operated so that they maintain even tension in the screen. If a discrepancy is detected, the speed of one or more of the motors may be adjusted in order to compensate and bring the tension back into line.

[0026]The position of the screen can be monitored by means of rotary encoders as described above. However, it may also be monitored by other means such as by optical distance measuring (e.g. with a laser). Most preferably, the tension in the screen is monitored by means of a tension meter (e.g. a load cell). Preferably tension meters are arranged at either side of the screen so as to monitor the tension being applied at both sides. The tension meter(s) can be positioned in a number of different places. They may be located at the point of attachment to the screen. If the motors are provided on end units which drive the screen along tensile wires, the tension meter(s) may be incorporated into the end units. If the motors are provided adjacent to the end supports, the tension meter may be positioned between the tensile wire and the screen. However, preferably the tension meter is not connected to the tensile wire or to the screen, but is connected to the end supports. As the tension in the screen varies, so does the load applied to the end supports. By monitoring the amount of load on the end supports, the amount of tension in the screen can be deduced. Positioning the tension meter in this way has the advantage that the tension meter does not move as the screen is deployed and retracted. Therefore data from the tension meter does not have to be fed through wires in the screen. Instead, the data can be communicated back to the control unit either by overhead wires, or more preferably underground wires. The control unit may control the motors in accordance with the sensed tension in order to keep the screen under appropriate tension during extension and retraction. In some embodiments, a tension meter may be employed in addition to detecting the velocity / position of the screen deployment.

[0035]In any of the above described covering apparatuses, a further way of increasing the tension in the screen during deployment is to introduce a difference in height in the end points of the screen, i.e. a transverse difference in height between the sides of the screen. If the end points of the screen are support poles, this may be achieved by making one support pole higher than the other. If the end points are fixed to a wall, the end points may be fixed at different heights on the wall.

[0036]With such a transverse difference in height of the end points, as the screen is extended, the screen is caused to tilt away from the horizontal. At the same time, as the screen is extended further, an increasingly greater transverse tension is applied to the screen. This balances the increasing need for tension as the screen is extended due to the increased weight of fabric and the increased susceptibility to external forces, e.g. from wind.

[0037]A further advantage of this difference in height is that as the screen is tilted away from the horizontal, a natural drainage path is created towards the lower end point. With large canopies, drainage can be a serious problem as water tends to pool on the canopy causing it to sag, which can in turn lead to accumulation of more water. If too much water is accumulated on the screen, the screen can be damaged. Smaller canopies which do not span a great length do not have such a problem with drainage as they can extend the screen at a steep enough angle to the horizontal that the rain will easily drain off the front of the screen. It is also easier with a smaller span to provide the tension required to prevent sagging of the screen at that angle. However, with larger screens, spanning a greater length, the angle of the screen cannot be made too steep without either raising the rear end of the screen or lowering the front end of the screen by excessive amounts. Also, the tension required to maintain a large screen sufficiently taut at such a reduced angle is prohibitively large. Therefore, providing a drainage route by angling the front of the screen to one side provides a much better solution for larger canopies.

Problems solved by technology

A major problem with all of these types of covering is providing sufficient tension in the screen so that the canopy does not sway unduly or flap in the wind.

However, the limit of tension which can be provided by springs is fairly low and varies with the length of the screen which has been extended.

Also, springs lose their elasticity over time or if they are extended too far.

This limit of tension has been a major factor in limiting the size (both width and length) of such covering systems.

Thus tension can be readily applied to the screen, and is limited only by the strength of the clamping system, the wires and the screen itself as opposed to springs as in the prior art.

However, the clamping systems will be subject to external forces such as wind, and other obstacles to movement such as debris on the tensile wires.

Furthermore, the clamping systems can slip along wires (e.g. if they are wet or greasy), again, in a non-equal fashion.

Also the motors may provide different drive forces, for example due to manufacturing tolerances or, variations in the power supply may cause one motor to pull momentarily stronger or to suffer a lull.

This can cause unbalanced pulling forces to be applied to the screen which can consequently be deployed and retracted in a lopsided fashion.

Not only does this make the screen less effective, but it can damage the screen.

These drawbacks will be particularly pronounced with larger screens where the clamping units have to travel greater distances and support heavier weights.

Where a large canopy is involved, a significant retraction force is required which can be difficult to provide.

When retracting the screen with unbalanced forces at either side of the screen, there is a further problem; with the unequal forces, the screen can become skewed and as it is retracted onto the storage roller, the screen may not roll up straight.

Also uneven pulling can lead to wrinkles forming in the screen.

As these wrinkles are wound onto the screen, they become folds and creases in the fabric.

Such wrinkles and creases create weaknesses in the fabric of the screen.

Under the high tensions involved in such canopies, there is a greatly increased chance of the fabric tearing at such weaknesses.

Once the screen has been deployed, even when the clamps are clamped in place, external forces such as wind can still cause them to move, thus resulting in a loss in tension or an uneven tension in the screen.

As the screen is raised significantly above the ground, wind passes both over and underneath the screen and the screen can easily catch the wind and experience high forces.

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