GB2238578A - Drive for up-and-over doors - Google Patents

Abstract

An up-and-over garage door is driven by a door-mounted, reversible electric motor via a winch 25 from which cable ends extend to springs and anchorages 57, 58 and 65, 66. The door latch has a hasp which is pivoted upwards via cable 64 to release the latch. One cable end may be secured to the garage roof (Fig. 7) or the cable ends may be secured together by a spring (Fig. 5). <IMAGE>

Description

IMPROVEMENT IN OR RELATING TO APPARATUS FOR DISPLACING A DOOR OR CLOSURE MEMBER This invention relates to a device for nechanically opening and closing up-and-over garage doors of the retractable type and up-and-over garage doors of the canopy type with vertical tracks.

1 in every 8 garages in the USA has an autocratic garage door operator.

By comparison in the UK the figure is more like 1 in 800. A recent survey gave no reason for this other than price differential with a median price of S200 in USA versus 300 in UK. However the survey did not address the element of different garage door construction between the two countries which mist also be a significant contributory factor.

In the USA over 90% of up-and-over and roll top garage doors are of the retractable type. This type can be defined as a door geonetrically arranged so that once unlocked it can be opened and closed silly by applying a horizontal pulling and pushing force at tbe top of the door.

For example the well known ceiling mounted chain drive garage door opener connected by a pivotal arm to the top of tbe door pulls rearwards with a linear motion to open the door and pushes forward to close it.

This is also true of the screw drive operator, which employs a rotating lead screw instead of a chain to apply the requisite linear force. Of the 8 nillion up-and-over garage doors in the UK less than 20% are of the retractable type whilst over 80% are of the canopy type with vertical tracks. This latter type can be defined as a one piece door geometrically arranged so that once unlocked it first has to be rotated about its roller wheels before it can be opened and when fully open it requires a vertical force downwards to close it.The difference in construction and operation of the retractable door which invariably has horizontal or essentially horizontal tracks (but not alwavs) and the canopy door which always has vertical tracks is explained in some detail in the Henderson Door Company's GB Patent 1382707 figs 1-6. Since most automatic garage door operators in UK are of U.S. origin and unable to operate the canopy type door the market in UK is severely curtailed. It is the object of this invention to describe a small low cost device which will operate both retractable and canopy type garage doors, a goal which has not been achieved before with any commercial success.

Additionally the motor drive can expeditiously be disengaged, if necessary from outside the garage, for reversion to manual operation.

Propriety automatic garage door operators are relatively large and heavy items. They are normally fitted to the ceiling of the garage requiring the installer to construct a substantial custom made metal suspension framework which cannot be standardised due to the variations in ceiling height and structure. lost operators traditionally employ a chain or leadscrew drive which makes them expensive whilst others employ a rack and pinion making these even wore expensive. All generally exDlov mains driven electric motors rated at 1/3 horse power which are also relatively exDensive. The operator to be described employs a double acting winch drum employing two winding cables1 the drum windinF on one cable as it winds off the other.It can be powered by virtually any type of car windscreen wiper motor, a relatively low cost type of motor because it is manufactured throughout the world in vast quantities and capable of producing high torquf. This helps in achieving other objectives of this invention which is to nake the operator smaller, lighter and allows a nore flexible and safer power source since the motor is capable of being powered by either a universally obtainable 12 volt battery or derived from the mains via an isolating transformer.

Since the motor and wincb drui in this invention is attached to and travels with the door a manufacturer could, but would be ill advised to use a mains motor, particularly in a domestic environment, due to the necessity for a trailing electric cable where a power source other than a battery is used. The size of the present invention allows it to fit comfortably into a box of approximate dimensions 10x10x8 inches (250x250x200sm) with a weight of less than 5kg. These figures are not intrinsic to any clans but to allow comparison with other automatic garage door operators and to illustrate the conmercial advantage of its suitability for 'over the counter' sale and easy transportablity.

Another important role of the present invention is to simplify and reduce the cost of installation by taking advantage of the structure and space provided by the door manufacturer and avoid the necessity to construct any substantial framework. Yet another objective is to simnlify construction of the operator (compared to for examp)e a typical conventional chain driven operator like that described in GB Patent 1384974) with all components easy to reach resulting in easy maintenance long life and low cost. In this respect the complete drum unit to be described can be stripped down to its last component in less than ten minutes emu ovine just two screwdrivers and one spanner.

According to the present invention there is provided a device for mechan cai'v opening and closing up-and-over garage doors of the retractabie anc canopy type by a reversible electric motor driven drum unit mounted on the door and having a cable spirally engaged with the drive in a wind-on wind-off configuration the two limbs of the cable dissngaF-ng with the drum each connected to a pincilbiock engagable with their eno-stop and having selective sprint tensioning means and means provided for unlatching the door locking device when the door is closed.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which Figure 1 shows in perspective the motor driven drum unit plus sample pulley, end-sto, pinchblock and spring.

Figure 2 illustrates mechanical operation of the retractable garage door Figure 3 illustrates operation of a locking device for the retractable door.

Figure 4 illustrates operation of the locking device employing a modified cable run.

Figure 5 illustrates mechanical operation of the canopy garage door by tfle crum un t and associates mechanism employing a closed winding cable loop and single spring tensioning means.

Figure 6 shows in perspective the door lever bracket enployed in operation of the canopy door.

Figure 7 illustrates mechanical operation of the canopy garage door by the drum unit and associated x mechanism employing an open winding cable loop and a two spring tensioning means.

Figure 8 shows in perspective a combined pulley/end-stop.

Any measurements given in this text are intended to convey an order of size and are not intrinsic to any clains. Beference to Fig 1 illustrates the drum unit 1 which is shown actual size. A metal or plastic box section frame 2 is screwed or bolted to the garage door via six fixing holes 3 including three complementary holes similarly placed on the other side of frame but out of sight due to the integral strengthening cover 4 on the rear face of the unit as seen in fig 1. A yoke shaped frame 5 pivotally engages with frame 2 via pivot pin 6 which is inserted through four coincident holes in frames 2 and 5. To prevent accidental extraction of this pin it has a rod end push-on-fit 7 at one end and a finger releasable K type locking pin (out of sight) at the other i.e.like a split pin but only one leg is inserted in the radial hole at the end of the pivot pin.Pivoting action in normal operation is prevented by pivot pin 8 (only half of it shown for clarity) complete with push-on-fit 9 and K type locking Din (not shown) identical to Divot Din 6 and similar to pivot pin 6 is inserted through four other coincident holes in frames 2 and 5. An alternative (as will be explained later in more detail) to pivot pin 8 or 6 is shorter pivot pin 10 which is inserted through only two of the coincident holes in frames 2 and 5 against the pressure of spring 11 and locked into position by insertion of a short length of solid wire 12 through a small radical hole 13 at the end of the pin. Vire 12 is joined to a flexible wire cable 14 by a small pinchblock 15, wire cable 14 passing through slot 16 integral with frame 5.The reason for solid wire 12 is that it does not flatten and distend under the compressive stress of spring ii as does flexible cable thus making extraction from hole 13 easier. Vindscreen wiper motor 17 is affixed to frame 5 by three bolts 18 (one out of sight).

Shaft l9, supported by two ball races 20 and 21 located in frame 2, is ininilly inserted into motor extension drive 22 and is rotated by the motor at typically 40-80 rpfl via the engagement of radial pin 23, inserted through a radial hole close to the end of shaft 19, and slot 24 in motor extension drive 22. A winch drum 25 with minimally integral flanged sides to prevent its cables falling off the edges is drivably engaged to shaft 19 by means of grub screw 26 . The fired location of drum 25 combined with a push-on-fit (out of sight) on the motor side of bearing 21 eliminates any end float of shaft 19.Shaft 19 is threaded between its bearings 20 and 21 on which are screwed two rotatably adjustable disc nuts 27 and 28 which are normally captive i.e.prevented from rotating with the shaft by an integral blade 29 on the inner face of detachable cover 30 (fig 2) engaging with the castellations on the outer periphery of the disc nuts. When the shaft and drum rotate the disc nuts move axially along the shaft in a direction dependent on rotation until contacting and depressing the lever of their respective limit iiicroswitch 31 (door closed) and 32 (door open) to stop motor rotation.

Fig 2 illustrates a typical retractable type upand-over door from inside the garage. It is a one piece door 33 pivotally connected at its two brackets 34a and 34b to two metal arms 35a and 35b , the arms pivotting on brackets 36 and 37 attached to the door jambs 38 and 39 and counterbalanced by springs 40 and 41. Wheels 42 and 43 (latter out of sight) run freely along the metal horizontal tracks 44 and 45 one of which has a rubber door stop 46 to prevent door overrun. The wheels 42 and 43 are supported on non-rotatable shafts in yoke brackets 47 and 48 bolted to the top corners of the door. Locking lever 49 is attached via a square shaft to a key operated handle (out of sight) on the outside of the door.Unlocking and turning the handle rotates the locking lever 49 which retracts the two locking bolts 50 and .51 (shown dotted) from behind the door jambs allowing the door to be opened. Before automating the door these locking bolts are removed in case they should foul door operation making the door handle and locking lever redundant. To automate door operation the drum unit 1 minus its detachable cover 30 is bolted or screwed to the door immediately beneath yoke bracket 47.

Flexible 2mm diameter wire cable 52 is attached to drum 25 via nipple retaining slot 53 (fig 1) then spirally wound anti-clockwise (as viewed from arrow A in fig 1) around the drum's periphery finally disengaging at about and in the direction of arrow B, passing over pulley wheel 54 (figs 1 and fig 3) screwed to the door jamb 38. The end of cable 52 is now passed down through the hole in end stop 55 screwed to the door jamb 38, then threaded through the axial hole in pinchblock 56 and doub3ed back before securing with two pinchbolts (note pinchblocks securing the winding cables have two pinchbolts for safety). Spring 57 is now hooked onto the formed wire loop at one end and hooked onto screw 58 fixed to door iam3 38 at the other end.An anchor plate consisting of a length of wood 59 supplied by the installer measuring about 35cm long by 12cm wide by 20inin thick is affixed to the rear of guide rail 44 by two bolts, one of which can normally be the bolt retaining the end stop 46, plus bolt 60. A similar length of wire cable 61 is now attached to drum 25 via nipple retaining slot 62 (fig 1) then spirally wound clockwise twice around toe drum to avoid strain on the nipple (not shown) before disengagement at and in the direction of arrow C (see fig 1) followed by passing the cable through end stop 63 and affixing to pinchblock 64 in a manner previously described. A spring 65, identical to 57, is hooked onto the formed loop at one end and onto screw 66 at the other end.

Although illustrated in fig 2 on the left hand side of the door (viewed from the rear) the system can just as easily be fitted on the right hand side the only difference being that the winding cables will come off the bottom of the drum instead of the top.

If a low voltage isolating transforDer is used to power the motor and control circuit these are placed in a box 67 which can be screw mounted at any convenient point including the ceiling, low voltage current being carried to the iicroswitches and motor terminals via wires in a trailing cable 68. With the garage door closed and with the drum unit and wire cables in the configuration shown disc nut 27 is manually rotated so as to just operate microswitch 31. Disc nut 28 is positioned about 10mm from disc nut 27 before temporarily fitting cover 30 with on of its six small reta5nin screws (not shown) so as to prevent disc nut rotation when the motor rotates. Finally mains power is connected to the transformer.

The electronic control circuit is the subject of its own patent and will not be described in any detail. When a switch (not shown) positioned in the garage or a renote control switch is pressed the motor will rotate in the correct direction and will stop when either disc nut operates its associated iicroswitch. Internediate stopping and starting when opening or closing and reversal of the door when closing is achieved by various safety devices, switch operation or remote control thus the user is always in control.

A description now follows of the door's operation, ignoring for the time being the question of unlocking and relocking the door. With the door closed, operating the remote control will rotate the motor anticlockwise. Initially lost motion (i.e. static rotation of drum 25) will occur for a fraction of a second as spring 65 is stretched due to the reactive load of the door. Once pinchblock 64 abuts its end stop 63 the drum unit 1 moves the door open, cable 61 winding onto tbe drum as cable 52 winds off. Xeanwhile the 'captive' disc nuts will move axially along shaft 19. When the door is fully open mains power is switched off and cover 30 temporarily removed allowing calibration disc nut 28 to be rotated so as to just operate microswitch 32 before replacing cover 30.

From now on disc nut 28 will abut microswitch 32 when the door is fully open to effect automatic operation. Switching the mains power on again and operating tbe remote control will tbis time rotate the motor clockwise and the door will be run closed once spring 57 has been stretched so that pinchblock 56 abuts its end-stop 55, cable 52 winding onto the drum as cable 61 Kinds off. Disc nut 27 should operate microsKitch 31 so that the motor stops when the door is closed and pinchblock 56 is within a centimetre or so of its end stop 55. if not then cover 30 can be removed once more to give disc nut 27 a final adjustment after which cover 30 can be permanently fitted complete with its six small screws.From now on disc nut 27 will abut microswitcb 31 when the door is fully closed to effect automatic operation.

At this point any attempt to push the door open manually will result in inchbiock 56 abutting its end stop 55. Since most if not all windscreen wiper motors have a worm and gear output drive they cannot normally be back-driven so the door is prevented from being opened.

However not only is it considered bad engineering practice to rely on gear friction to hold a load but anyone attempting to push the door open accidentally or intentionally could cause danage to tbe drum unit mechanism perhaps even managing to strip the teeth on the motor worm wheel which is invariably made of nylon.To avoid this possibility and to provide more security a far stronger locking mechanism is called for and will be described after tbe following notes: l. Since it is the end stops 55 and 63 which take the full load of the door the only role of the springs 57 and 65, which can be made of any materiai having the characteristics of a spring1 is to provide sufflcint tension to take up the slack on their resDective cables when wincing-off the drum thus preventing the coils from unwinding which could lead to subseouent miswnndin. This tensioning of the cables bv either the door load or the associated spring could be termed selective tensioning.The tension springs could be substituted with compression springs but arrangements would have to be made to prevent the springs from bending under compression. Since short term stretching of the wire cable below rated load is negligible it is possible to dispense with the pinchblocks and springs and connect the cables to fixed points. However not only does the inclusion of the pinchblocks and springs take care of long term stretching of the wire cable but the length of the cable can be deliberately increased to increase lost motion, utilising coincident movement of the wire during static rotation of drum 25 to perforn some task which has to be completed before movement of the door occurs such as unlocking the door, as will be described later.

2. From the nearly closed position some retractable doors close naturally as the door springs 40 and 41 go over-centre. This causes spring 57 to relax momentarily and pinchblock 56 moves downwards. With tbe door closed continued motor rotation results in static rotation of drum 25 (lost motion)allowing motor switch-off at any time before pinchblock 56 moves back up to its end-stop 55. If on the other hand the door has to be pushed closed all the way pinchblock 56 may remain bard up against its end-stop on door closing requiring the timing of motor switch-off to be more precise. Too earlv may result in incomplete closure and too late may result in overload devices re-opening the door.

For those doors which do not get the full benefit from the door sprints going over-centre tnis can be augmented by adjustment of the door springs 40 and 41 and/or increasing the tension of spring 57.

3. It would be Dossible in the case of the system described to take the wire cables over the top of track 44 and join them together via a single common spring situated between two separate end stops to close the cable loop. However this rewires longer cables, one or more extra anchor plates not easily fitted to track 44 and guarantee wheel 47 will not be obstructed plus at least three extra pulleys to navigate the cables around the track, change their direction and maintain their alignment.

This all adds up to longer installation time and its feasibility very much dependent on the subtle omissions and variations in the construction of some versions of retractable door tracks. Also the single common spring precludes increasing the tension of one spring in isolation to the other. However in the case of tbe canopy door operation to be described later a closed loop system can be a viable alternative to the open loop system illustrated in fig 2. An alternative to spring tensioning is to substitute one or both springs with a small weight acted upon by gravity. Unlike the spring a weight maintains a constant force irrespective of wire cable movement.

4. The drum diameter is constant along its length so the rate and amount of wind-on wire equals the wind-off wire. If required the drum periphery can have a shallow spiral thread for wire guidance. A differential winding drum can have certain advantages where high torquf forces are encountered on the initial opening of a large door. Such a drum can take several forms such as a cone shape having different diameter multiple grooves. Alternatively it can be a twin grooved pulley substituted for the drum with each wire forming a multi-lavered winding in its own groove. The action of rotating the pulley is essentially as described before except initially the smaller diameter of the wind-on coil will result in higher pulling forces for the same torque input.However, the rate of wind-on will be less than wind-off until about the half-way point when the situation will reverse.

Employing this method needs longer spring tensioning means to take up the slack in the winding-off cable up to the half-way point.

5. Alternatives to the preferred self contained linit iicroswitches described would be either to mount then both on the door in such a manner that the down switch is operated by a bracket on the door jamb and the up switch operated by a bracket on the rear portion of the guide rail, or instead to mount the down switch on the door jamb and the up switch on the guide rail, both operated by either one suitably sited bracket mounted on the door or two separate brackets. Both alternatives can be made to work so long as the speed the iicroswitches meet the brackets is minimized. However it entails fitting more components, adjustment can be time consuming and tbe microswitches are vulnerable to being damaged.Alternative limit switching can employ other proximity switching methods such as a reed switch and associated magnet or optical methods but would be more expensive. Note that although in tbe present design two disc nuts are emp]oyed only one is necessary to operate botb microswitches if the position of one microswitch is made adjustable.

6. Although overload sensing in both the door opening and closing node is presently carried out electronically a spring overload device can be emD,oved. Alternatively or in addition a mechanical clutch system can be DrOV) àed in the motor drive.

7. Bmp:toying a car windscreen motor lends itself to several sources.

confizurations and siting of the power supply. Since door opening and closing times are typically 10 seconds and on average the door is opened twice a day a sealed typically 12 volt 2.6 ampere battery can be strapped to the door immediately below the drum unit removing the battery occasionally for re-charging. A more sophisticated method is to arrange that two electrical contacts mounted on the door and in circuit with the battery abut two electrical contacts mounted on the door jamb in circuit with a low voltage mains derived power source so as to allow automatic battery charging to take place whenever the door is closed.

This eliminates the requirement for a trailing electric cable. Another alternative is to power the remote control receiver,electronic control circuit and motor via a common isolating transformer witb or without battery back-up. Typically without battery back-up requires only a SOVA transformer for a single retractable or canopy garage door which bears testimony to the economy and efficiency of using a windscreen wiper motor besides the safety factor of the low voltage trailing lead in this type of operator.Another particular advantage of using tbis transformer is that if for example the door is obstructed by a car, child's toy or there is a mechanical fault then not only is maximum transformer output current limited to typically 7 amps or so thus limiting the torquf of the motor but monitoring of the associated voltage reduction affords higher resolution and a more precise threshold for the triggering of electronic safety devices than a mechanical device such as a string not to mention being simpler since the source signal is already resident in a compatible form within the control circuit.

8. Although in this embodiment the drun unit 1 is fitted near the top corner of the door it can alternatively be pivotally connected to a bracket affixed to the top rear centre of tbe door (not shown). On door opening the drum unit pivots forward so as to keep the top of the drum above the' level of the top of the door. Pulley 54, end stop 55, screw 58, associated spring 57 and wire 52 can easily be run horizontally along the rear face of the lintel (as illustrated in fig 4). However end stop 63 and screw 66 do not have a convenient fixing point at the same height just to the rear of the door's open position which entails tbe fitting of a substantial frame attached to the ceiling or spanning the metal tracks 44 and 45 capable of taking the re-active load of the opening door.Since one of the objects of this embodiment is to use structures nornally provided by the door manufacturer and avoid the constructing of substantial framework the preferred position of the drum unit is the edge of the door as described.

Fig 3 illustrates a locking latch system 69 for the retractable type door which is preferable to holding the door closed solely due to irreversible drive of the motor as already mentioned. A latching bolt 70, wedge shaped at the top, slidably engages with bracket 71 screwed or bolted to the top centre of the door 33. An inverted U shaped rod 72 inserted through height adjustment hole 73 in the latching bolt slidably enrages with bracket 71 through two holes 74 and75 and straddles a fully extended compression spring 76.A flexible wire cable 77 connected to the bottom of the locking bolt with the aid of a pinchblock 78 is connected (not shown) at the other end to the door locking lever 49 which is re-osition horizontally on its square shaft (note fig 2 illustrates a slightly modified arrangement as will be described). A cranked hasp 79 constructed from substantial metal rod is freely pivotable in the vertical plane about two brackets 80 and 81 screwed to the lintel 82. Tbe natural position is for the craned portion of the hasp to be horizontal because one end of the hasp faces downwards to rest on the lintel whilst the other end protrudes outwards horizontally to increase the downward turning moment.This downward turning moment couid be increased by spring loading (not shown) or even made adjustable by a movable weight 83 (sbown dotted) but in practice neither is found necessary. Thus the hasp can only pivot upwards from the position illustrated in fig 3. One end of a light flexible cable 84 such as nylon chord is threaded through a hole 85 in the protruding end of the hasp and knotted underneath to provide a firing. The other end of the chord is threaded through a U nail 86 affixed to the lintel, taken over pulley 87 and attached to the winding cable 52 via pinchblock 88 as illustrated or alternatively taken through the hole in end-stop 55 and connected to the upper hook of spring 57.

When the drum unit 1 is installed on the opposite side of the door the locking system 69 is merely a mirror image of that described. An alternative configuration is illustrated in fig 4 where instead of positioning end-stop 55, pinchblock 56, spring 57 and screw 58 on the door jamb thep are positioned in a horizontal line on the lintel 82 instead, extending winding cable 52 to suit which is additionally taken over pulley 87 to effect a change in direction. Operation of the hasp 79 and latching bolt 70 are the sane as previously described.

As illustrated in fig 3 and already described, when the door is closed spring 57 is extended with pinchblock 56 close to its end-stop 55, tbe relaxed chord 84 allowing the crank portion of tbe hasp to surround the latching bolt. Any attempt to push the door open will cause the rear straight edge of the latching bolt to contact the hasp preventing any further rearward movement of the door. However when automatic operation takes place the first action as already described is for drum 25 to rotate statically for a moment until spring 65 (fig 2) is extended causing spring 57 to relax and in doing so pulls downwards on chord 84 which in turn rotates the hasp upwards allowing the extended latching bolt 70 to pass by. The situation on the door closing will vary according to the door's closing characteristics.With the benefit of lost motion mentioned previously in note 2 the hasp will be up when the bolt 70 makes its forward pass, the hasp returning to the horizontal position once the door closes and pinchblock 56 moves upwards towards its end-stop 55. With minimal lost motion the hasp may be much lower or already in its horizontal position resulting in bolt 70 abutting the hasp. In this case the wedge shaped top of the bolt will rotate the hasp upwards sufficient to let it pass after which the hasp returns to the horizontal position under the influence of gravity thus locking the door closed.

In the event of an electrical or mechanical failure it is a great advantage if means are provided for expeditious reversion to manual operation i.e. unlock the door and allow it to be opened and closed nanually. From inside the garage this is achieved by pulling out the K type locking pin and withdrawing the upper pivot pin i.e. pivot pin 6 if the drum unit is fitted on the left hand side of the door or pivot pin 8 if on the right hand side, allowing frame 5 to pivot downwards about frame 2 thus disengaging tbe pin 23 and slot 24 motor drive.Either has 79 can be pivoted upwards by hand and fixed into this position until re-instatement of automatic operation or if use of the door locking facility will be required the outside door handle can be uniocked and on rotation will via locking lever 49 retract locking bolt 70 downwards to clear hasp 79 allowing the door to be opened and closed manually the wire cables 52 and 63 winding on and off the drum as normal.Subsequently automatic operation can be re-instated by rotating frame 5 to re-engage the motor drive and re-inserting the upper Divot pin. Lixnit microswitch adjustment will not be affected by manual operation so long as the motor drive is re-instated with the door in the same position as it was disengaged which will normally be with the door cZoc In the case where the garage door 33 is the only means of entry into the garage then it is essential that reversion to manual operation can be carried out from outside the garage. This is accomplished by employing tbe shorter pivot pin 10 in the upper pivoting position when installing drum unit l and connecting flexible cable 14 via pinchblock 78a to locking lever 49.If reversion to manual operation now becomes necessary unlocking and rotating the outside door handle will via rotation of locking lever 49 result not only in door locking bolt 70 being retracted downwards but also wire 12 being withdrawn from its radial bole 13 by flexible wire 14 allowing spring 11 to withdraw pin 10 from frames 5 and 2 whereupon the weight of the motor, being well to one side of the lower pivoting pin causes frame 5 to pivot downwards to disengage the pin 23 and slot 24 motor drive. To augment the weight of the motor, pinchblock 15, its position having been suitably adjusted, abuts and helps rotate frame 5. This now allows the door to be opened manually.Note that although out of sight in figs 1 and 2 there is a second slot in frame 5 in line with the lower pivoting pin, which of course becomes the upper pivoting pin when the drum unit is installed on the other side of the door.

A slightly Modified arrangement illustrated in fig 2 dispenses with cable 77. Instead cable 14 connected to pinchblock 15 at one end as shown in fig 1 is threaded through pinchblock 78 then through the bottom hole in latching bolt 70 before connecting to locking lever 49.

inchblock 78 is positioned and tightened down such that on rotation of locking level 49 it will abut and lower latching bolt 70 after pinchblock 15 has rotated frame 5 to disengage the motor drive. Xost if not all propriety locking levers afford enough rotational movement to ow this sequence.

A brief description of a typical canopy type door will now be given with reference to Fig 5. For the sake of clarity the left hand side of this figure illustrates the essential details of the door system but it will he understood that the door's structure is svmetrically displaced on either side even though only one number may be allocated in tbe text.

Meanwhile the right hand side of the figure illustrates the components employed in automating the door. Two small freely rotating wheels 89 (shown dotted) are affixed to both sides of tbe one piece door 90 via their non-rotating sbafts and brackets 91 and 92 respectively . These wheels are constraIned to run along their vertical metal tracks 93 affixed to the rear face of their respective door lambs 94. Two metal arms 95 are Dìvotailv connected to the door lintel 96 < on some models to the upper door jambs) at the top and to,tbe door at their bottom. The inclusion ci these arms means the door is also pivotal about wheels 89.

A iar torsional (sometimes tension) spring assembly 97 to counterbalance the door is affixed to and occupies virtually the whole of the door lintel 96 and is connected to the shafts 91 by a wnre 98 running down each vertical track 93. A metal weatherstrip 99 is affixed to the rear edge of the door and overlaps the door janibs to a varying degree dependent on manufacturer. At this point it will be mentioned that although geometrically similar virtually every model of the canopy door, even those of the same Danufacturer, vary in some way or other all of which often deny use of the lintel and upper half of the door jambs for placement of components to automate the door.These space restrictions added to the fact that some door jambs may be only 1 3/4" wide (44mm) and often abut the side wall all contribute to the reason this door has not been successfully automated before. An outside key operated handle (not shown) when rotated also rotates the concentrically nivotted locking lever arm 100 which due to its attachnent to tbe self locking latch assembly 101 by wire 102 retracts the self latching sprint loaded plunger 103 to unlock the door. Another way to retract the plunger if one is inside the garage even with the outside door handle looked, is to Dull the wire 102 sidewards from a position approximately mid-nay between the latch 101 and the locking lever 100 and is the method which will be used in this embodiment. As explained in patent 1382707 page 1 line 48, once unlocked the only way to overcome the geometric locus is to rotate the door about wheels 89 (typically a minimum of 10 centimetres as measured at the top of the door). Only then can the door be raised by applying an upward force. preferably from a position in the vicinity of the wheels,-which also further rotates the door.When the door is fully open it is horizontal with about one third of the door projecting outside tbe garage forming a canopy. A vertical force downwards on the door froi a position forward of the door pivot point of arm 95 (the further forward the better) will cause the door to descend and momentum will rotate it back to the vertical and closed position whereupon the latch will self lock the door but the latter action is not guaranteed unless means are provided to prevent the door bouncing back before the latch has tine to lock.

To automate the door entails first screwing or bolting the standard drum unit 1 to the door typically 3"- 8" C37 - 200my) above shaft 91 with the drum 25 overhanging the side of the door. The only extra accessory employed in automating the canopy door is a simple door lever bracket 104 illustrated in more detail in fig 6 (an alternative could be a linearly moving spring loaded lever). This is screwed to the rear edge of the door about halfway between drum unit 1 and the garage ceiling (but not higher than the top corner of the door) via holes 105 and 106 so that the pivotal arm 107, with a retaining push-on-fit 108 and 109 at each end, overhangs the side of tbe door, light spring 110 pivoting arm i07 forwards against the door jamb.A wire cable 111 is threaded through a hole in the arm 107 up to its nipple 112 then threaded through tube 113 before connecting it to wire 102 via pinchblock 114. Note that similar to the retractable door the drum unit 1 can be fitted to either side of the door so iD the case illustrated in fig 5 the door lever is placed upside down which does not affect its function. From this point either the 'closed loop' method illustrated in fig 5 or the 'open looD' method illustrated in fig 7 can be employed to automate the canopy door.

The 'open loop' method is used if a weight (strung over a pulley if the spring it replaces is pulling in a horizontal direction) is substituted for either spring 57 or 65 or where there is no space on tbe upper door jamb to fit the various components including pulley/end-stop 115 or where two spring tensioning means are employed in order to adjust one in isolation to the other. Pulley/end-stop 115 (abbreviated to p/e 115) is illustrated in more detail in fig 8. Pulley 116 is rotatably mounted in channel 117, the integral end-stop 118 face having a hole 119 in it to allow winding cable 52 or 61 to be threaded through then taken round the pulley. The p/e is screwed down via the two holes 120 and 121 (shown dotted) situated at the bottom of the channel.Note this pie is a recent development and is a direct replacement for pulley 54, and ninus its pulley 116 a direct replacement for end stops 55 and 63.

In the closed loop system illustrated in fig 5 pie 122 is screwed to the door jamb so that its pulley is approximately level with drum 25. P/e 115 is screwed to the upper part of the door jamb at least 20" (500cm) higher than p/e 122 to accornodate one single spring which can be either 57 or 65. P/e 123 is screwed to the underside of ceiling joist 124 at least 6" (150mm) rearwards of the door lever 104 and approximately inline with the door lever and p/e 115. Note that if the ceiling joists happen to be at 90 degrees to that illustrated it may be necessary to screw a piece of wood across two adjacent joists to position D/e 123.

Wire cable 52 is wound onto drum 25. taken round the pulley on pie 122 and threaded through the integral end-stop hole before affixing to pinchblock 56, forming a loop as described previously on which to hook spring 57 or 65. Vire cable 61 is now wound onto drum 25, taken under lever 107, round the pulley on pte 123 (integral end-stop not used), round the pulley on p/e 115 and threaded through the integral end-stop hole before affixing pinchblock 64 and hooking onto spring 57 or 65 dependent on which one is being used.

In the open loop system illustrated in fig 7 p/e 122 is screwed in the same position as before but with the face of the integral end-stop facing downwards. P/e 115 is not used. Wire cable 52 is wound onto drum 25, taken round the pulley on p/e 122 and threaded through the integral end-stop hole before affixing pinchblock 56 and hooking onto spring 57 which is also hooked onto screw 58 affixed lower down the door jamb. Vire cable 61 is now wound onto drum 25, taken under lever arm 107, round the pulley on p/e 123 and through its integral end-ston before affixing pinchblock 64 and hooking on spring 65 which is also hooked onto screw 66 affixed to an adjacent ceiling joist as shown or if the joists run at right angles then to a piece of wood affixed to span adjacent joists < not shown).

Both open and closed loop operations are similar. When the motor rotates so as to open the door the first action is for the pinchblock 64 to be Dulled up to its p/e 115 (closed loop) or pIe 123 (open loop) due to the door load after which wire cable 61 takes up the shortest route between drum 25 and the pulley in p/e 123, in the process first piVotin the lever arm i07 rearwards away from the door which via cable 111 Dulls cable 102 sidewards to retract the latch plunger 103 to unlock the door followed bv rotation of the door about wheels 89 with further rearward movement of tbe now non-pivoting door lever arm 107.Once cable 61 has taken up the shortest route further rotation of the drum pulls the drum unjt 1 upwards towards p/e 123 which in the process pulls the door up its vertical tracks, cable 61 winding on as cable 52 winds off the drum.

Meanwhile lever arm 107 completely disengages from cable 61 as the door rotates rearwards. Once fully open the drum unit microswitch 32 is operated by its associated disc nut 28 as described before for the retractabie door. On door closing the first action is for pinchblock 56 to be pulled up to its p/e 122 after which the drum unit 1 drives the door downwards towards p/e 122, the door rotating slowly towards the vertical. Such is the geometry of the door mechanism that when nearly closed the rate of door rotation increases exponentially (typically 400mm as measured at the top of the door in the last 50mn of vertical door movement) allowing momentum to move it to the closed position and remain closed.The latter is guaranteed because the pulley in p/e 122 is approximately level with the drum 25 ensuring the re-active force between p/e 122 and drum 25 is approximately at 90 degrees to the door's axis such that the door is capable of being closed with or without the benefit of door momentum. Meanwhile lever arm 107 has re-engaged with cable 61 in readiness for the next opening operation. Tbis re engagement causes spring 65 to expand which beneficially impedes too rapid a door rotation caused by door momentum allowing it to close more gently than it is prone to do without this restraining force. In this respect too the open loop system is better because the tension of spring 65 can be adjusted in isolation to spring 7.

It will be appreciated that during door operation the winding cable run is constantly shortening and increasing. These changes are absorbed by the -spring tensioning means.

Reversion to manual operation is carried out in a similar manner to the retractable door. After using the original key to unlock the canopy door, rotation of the handle rotates the door locking lever 100 resulting in both the spring loaded plunger 103 being retracted from the door latch to unlock the door as is normal for that type of door and siDultaneously disconnecting the motor drive due to retraction of pin 12 via wire cable 14. In a very few cases where a locking lever cannot be adapted as described a coimercially available key released tumbler block (not shown) connected to wire 14 and accessible from outside the garage can be employed. Turning the key frees the tumbler block which can be puzzled manually as far as is necessary to disengage the motor drive.

Finally to clear up a few points: 1. Although there are two winding cables they not only appear like one but in fact could be substituted with one cable by for example dispensing with the nipples and either threading the single cable through an axial hole in the drum or placing the centre of the single cable in an axial groove in the surface of the drum before winding the cable on the drum. For this reason although functionally no different one can refer to winding cables or a winding cable.

2. The holes in the end-stoDs could be substituted with open-ended slots. Although slightly more convenient for engaging the winding cables it is felt that the holes are more tolerant to slight misa~ignment of the cables and give better assurance the rinchblocks will never get past tbe end-stops given tbe dire conseauences to the light springs and subsequent malfunctioning of the mechanism if they do! 3. In the case of the retractable type door the drum unit 1 with a free running wheel (like wbeel 42 or 43) on an extended shaft 19 can be substituted for one of the yoke brackets 47 or 48 and associated wheels 42 or 43. To accommodate the extra length of the drum 25 entails repositioning of the horizontal track 44 or 45 which not only coniplicates and increases installation time but is not possible where there is insufficient side clearance in the garage. Another disadvantage of this method is that the drum unit has to bear part load of tbe door.

4. ADart from the door lock assembly of the retractable door and the door lever 104 of the canopy door, both of which are cheap enough to be included in every kit, all other components to automate both doors are common and thus served by one kit of parts.

Claims (12)

CLADS

1. A device for mechanically opening and closing up-and-over garage doors of the retractable type by a reversible electric motor driven druid unit mounted. on the door and having a cable spirally engaged with the drui in a wind-on windoff configuration the two limbs of the cable disengaging with the druM each connected to a pinchblock engagable with their end-stop and having selective spring tensioning Deans and means provided for unlatching the door locking device when the door is closed.

2. A device for nechanically opening and closing up-and-over garage doors of the canopy type by a reversible electric motor driven drum unit mounted on the door and having a cable spirally engaged with the-^drum in a wind-on wind-off configuration the two limbs of the cable disengaging with the -drum each connected to a pinchblock engagable with their end-stop and having selective spring tensioning means and neans provided for unlatching the door locking device when the door is closed.

3. A device as defined in any previous claim with neans for expeditious reversion to nanual operation carried out either from inside or outside the garage.

4. A device as defined in any previous claim employing a low voltage powered electric motor.

5. A device as defined in any previous claim employing a windscreen wiper type motor.

6. A device as defined in any previous claim where at least one means to stop motor rotation is by operation of a mechanical switch.

7. A device as defined in any previous claim where at least one means to stop motor rotation is by a captive nut, moving axially along a shaft rotated by the motor, abutting a mechanical switcb mounted on the drum unit.

8. A device as defined in any previous claim where the tensioning means can be any materia' having the characteristics of a spring or a weight or both.

9. A device as defined in any previous claim where when two tensioning means are provided can each be adjusted independently.

10. A device as defined in any previous claim where the winding drum is constructed so that the cable is capable of winding on and off at different rates.

11 A device as defined in claim 2 where the first significant action to open the canopy door is to unlock the door latch and the second significant action is to rotate the door about its roller wheels to allow the door to be raised.

12. A device as claimed in any previous claim arranged and adapted to operate substantially as hereinbefore described or described with reference to figures 1-8 of the accompanying drawings.