Improved roller shutter assembly

Abstract: The invention provides an improved roller shutter assembly 10 including a cylindrical core 12 having end blocks 14 rigidly located at each end. At least one end block is provided with a mounting block 16 rotatably mounted in a hole 20 in the end block 14. Provided between the mounting block 16 and the end block 14 is an annular space 32 which encloses a coiled spring 30. One end of the spring 30 is attached to the end block 14 and the other end to the mounting block 16. Thus as the blocks are rotated with respect to each other the spring is tensioned to provde a counteracting spring force to aid rewinding. Enclosure of the spring means at the end blocks provides for easy maintenance and simplified construction. Each end block 14 may be provided with springs if desired. In a further embodiment the end block 14 is provided with an external peripheral cam shaped surface so as to facilitate even winding of a slatted blind.

Description: This invention relates to an improved roller shutter assembly especially for a roller shutter intended for use as a garage door. Spring tensioned roller shutters or blinds are commonly known for many uses for example as cabinet shutters, door or window shutters etc. In such constructions it is usual for the assembly to comprise a generally cylindrical roller onto which the shutter or blind is wound, the roller being journalled at each end by carrying means which are fixed relative thereto. The roller is connected to the carrying means by way of a coaxial central core or similar arrangement and by a helical spring such that rotation of the roller in one direction will cause tensioning of the spring. When the tension is released rotation of the roller in the opposite direction is caused. It will thus be appreciated that in this way a shutter attached to the roller may be unfurled causing tensioning of the attached spring which is then held in place by a ratchet or similar mechanism. When the ratchet is released the tension in the spring causes the roller to rotate thereby rewinding the shutter thereon and raising it from its closed position. Such an assembly has several problems. Firstly it is not easy to maintain the assembly in working condition especially if there is a breakage of the helical spring which will require complete disassembly in order to rectify. Furthermore the helical spring must be pre-tensioned before use which can be especially difficult where the roller shutter is intended for use as a garage door and is consequently of a substantial weight. Furthermore the construction described is not easy to motorise as the drive must be applied to the cylindrical roller and not to the carrying means which are the more easily accessible. EP-A-0187685 discloses a roller shutter in which a spring is detachably slidably mounted on a length of tube. Further disadvantages of the known configuration are especially apparent when the known construction is used for a garage door comprising a plurality of metal or similar slats. The substantial size of a garage door means that the blind in question will invariably be fairly heavy and the slats of fairly broad width. This causes a problem insuring the smooth winding of the slats which because of their thickness will form an irregularly shaped roll. Furthermore there will always be a transition point between one layer of slats around the roller and the next causing a bump or protrusion on the rolled shutter surface. FR2344705 discloses a shutter suitable as a garage door which has a reduced co-efficient of friction to facilitate winding and unwinding of the shutter. It is an object of the present invention to provide an improved roller shutter assembly in which the construction is simplified as compared to prior assemblies and which will permit easy motorisation. With this object in view a first aspect of the invention provides an improved roller shutter assembly comprising a shutter comprising a plurality of linked slats; an elongate core; at each end of the core an end block mounted for rotation about a carrying mounting block; each end block being of a diameter larger than the elongate core and onto or off which the shutter is to be wound or unwound respectively; and in a space between the carrying mounting block and end block, a coiled clock-type spring having opposite ends connected one to the end block and the other to the carrying mounting block so as to be tensioned by rotation of the end block relative to the carrying mounting block during winding or unwinding of the shutter; characterised in that each end block is profiled to provide a peripheral cam surface having a substantially radially disposed step, which steps of the respective end blocks are in alignment with one another so as to provide respective seats for an end slat of the shutter; and each carrying mounting block has a spring loaded retractable mounting pin received in a housing provided in the carrying mounting block such that the assembly may be reasonably mounted in a supporting bracket. Thus, in order to provide for more even rolling of a slatted shutter, each end block is shaped to provide a cam surface having a substantially radially disposed step at which an end of the shutter is to be located. With such a radially disposed step it will be appreciated that the configuration is, advantageously, used with a roller shutter comprising a plurality of rigid slats. In such an arrangement the first slat of the shutter lies radially adjacent to the step such that there is a smooth winding of successive layers around the end block of the roller blind assembly. Where the length of the slatted shutter is over one metre it is advantageous to provide the elongate core with an additional centre block shaped correspondingly to the end block in order to provide additional support. The spring means is in the form of a coiled spring one end of which is connected to the end block and the other end of which is connected to the carrying mounting block. Such spring is, advantageously, disposed around the carrying mounting block in a space provided between the carrying mounting block and the surrounding end block. Advantageously, the carrying mounting block is provided with a spring loaded retractable mounting pin received in a housing provided in the carrying mounting block such that the assembly may be mounted in a supporting bracket. In embodiments of the invention the core of the shutter is arranged to be rotated by way of motor means and the assembly is further provided with sensor means operative to sense resistance to unwinding of the shutter and on sensing same operative to stop rotation of the roller shutter via switching of the motor means. Advantageously the switching of the motor means is such as to automatically reverse the direction of the motor drive such that on its next operation the shutter will be wound onto the core and hence raised from its closed position. Advantageously a separate sensor is provided operative to detect the shutter in its raised or fully wound position and prevent further rotation of the core by switching of the motor means. Embodiments of the invention will now be described further by way of example with reference to the accompanying drawings in which:- Fig. 1 is a sectional view of an end block of a roller shutter assembly. As explained below, the assembly is not within the scope of the accompanying claim 1, but does show clearly the construction of a carrying mounting block suitable for a roller shutter assembly embodying the invention; Fig. 2 is an end view of an end block of an improved roller shutter assembly according to an embodiment of the invention; and Fig. 3 is a block diagram illustrating a further embodiment of the invention. Referring firstly to Fig. 1, the illustrated roller shutter assembly 10 includes an elongate tubular roller core 12 to which is attached at each end an end block 14 of which only one is shown for simplicity. The end block is circular in shape and fits within the open end of the tubular core 12 and is secured there by way of, for example, a screw or other similar fastening means (not shown). Although such a circular end block is not an embodiment of the invention, much of the following also applies to the Fig. 2 embodiment. A carrying mounting block 16 is provided with a shaft portion 18 which is rotatably mounted in a hole 20 provided in the end block 14. The shaft 18 is retained in the hole 20 by projecting lugs 19 which engage with the end block. In this way the end block 14 is rotatable about the block 16. In order to provide the releasable mounting of an assembled roller between two supporting brackets (not shown) mounting pins 22 are provided in a housing 24 of each carrying mounting block 16. To permit depression of the mounting pin 22 a spring 26 is located within the housing 24 and operative to urge the mounting pin 22 outwardly of the housing 24. Outward movement of the mounting pin 22 is constrained by provision of a cap 28 secured over the housing 24 and having an inwardly directed lip 38 which engages with shoulders 29 on the pin 22. As the carrying mounting block 16 should be carried by the support brackets so as to be relatively non-rotatable with respect to the roller it is advantageous to provide one or other of the mounting pins 22 as a square or other regular polygonal cross-section. In this way rotation of the pin 22 within the support bracket is prevented. Both pins could be provided with the necessary square cross-section, however this is not necessary and only one such pin need be provided for correct operation of the roller shutter. When the shutter (not shown) is lowered it will require rotation of the roller in order to rewind it. In order to accomplish this a clock type coil spring 30 is arranged in a space 32 formed between the end block 14 and the carrying mounting block 16. This space 32 is approximately annular and the coil spring is arranged within it such that the spring's innermost end is connected to the carrying mounting block 16 and the spring's outermost end is connected to the end block 14. Thus, as the end block is rotated with respect to the carrying mounting block 16 the spring 30 is tensioned or relaxed according to the relative direction of rotation. The spring 30 is preferably disposed such that unfurling of a shutter attached to the roller 12 causes tensioning of the spring 30 sufficient to provide a rewinding force on the roller 12 when the shutter is permitted to rise. In order that the shutter is retained in its unwound configuration, against the action of the spring 30, a ratchet or similar mechanism (not shown) is provided such that the roller may be selectively held at any desired position and easily released to be rewound under action of the tensioned spring 30. Turning now to Fig. 2, an example of an improved roller shutter assembly according to the invention is illustrated in which the end block's peripheral surface is shaped as a cam profile 40 having a step 42, substantially radial of the axis of rotation, at one point on its periphery. This arrangement is intended for use with a roller shutter comprising a plurality of linked slats (not shown). In a roller shutter in which the blind is formed of a fabric or similar thin flexible material it will be appreciated that no discernable step is formed at the starting point for the winding of the material around the roller. Thus there is a consistently smooth take-up during winding and unwinding. However,in the case of a slatted shutter construction in accordance with the invention, the starting point provides a significant radial step about the axis of rotation and consequent problems in providing a smooth and consistent take-up of slats onto the roller. In the proposed arrangement the step 42 provided on the periphery of the cam profile 40 is intended to seat the first slat of the shutter. It will be appreciated that when the shutter is rolled around the cam profile the second layer of slats will be smoothly and easily wound around the first without a sudden increase in rotational radius as would normally be the case. In such an arrangement the slats are supported by the cam profile and not on the cylindrical roller 12. Thus, as compared to the assembly illustrated in Fig. 1, the roller is preferably replaced by a tubular core, advantageously of square cross section, which fits within the end block 14 such that the profile will stand proud of the core's surface. It will also be appreciated that in this configuration there is no requirement for a cylindrical roller 12 to be provided around the end profile and a cylindrical or tubular shaft can be provided extruding between two end blocks 14 which shaft does not contact the slats of the shutter construction. Where the width of slats exceeds one metre it may be required to provide additional support at least at the centre of such slats (and in some cases at other points as well). In such an instance a third (or more) cam profile 40 will be provided spaced along the central shaft and with its step 42 in alignment with respective steps 42 on end block cam profiles 40. In this way the slats of the shutter can be supported across its entire length when so required. Turning now to Fig. 3 a complete garage door roller shutter assembly is illustrated as a block diagram to illustrate the operation of a further aspect of the invention comprising feed-back control apparatus operative to sense the position of a roller shutter and control drive means attached thereto. In the figure a roller shutter assembly comprises a roller 50 about which is wound a shutter 52. In common garage door configurations the shutter 52 will comprise a plurality of rigid slats in order to provide a door having a required structural integrity. The roller 50 has a shaft 54 to which is attached motor drive means 56 operative to cause rotation of the shaft in response to operation of a switch 58. A sensor 62 is mounted on or adjacent to the shaft 54 so as to sense resistance to rotation of the shaft as would be caused by the blind's lower edge reaching ground level. On sensing a resistance to rotation of the shaft the sensor 62 passes a control signal to a feed-back controller 64. In response to the receipt of this signal the feed-back controller 64 sends a control signal to the switch 58 turning same to off position and hence stopping rotation of the shaft 54. Furthermore the feed-back control also actuates second switching means 60 operative to reverse the polarity of the electrical supply to the switch 58 such that actuation thereof will now cause rotation of the shaft 54 in the opposite direction. A second sensor 66 is mounted below the shaft adjacent to one edge of the shutter 52. This second sensor 66 is operative to detect the shutter 52 when it is in its raised position and actuates the feed-back controller 64 to firstly stop rotation of the shaft 54 and to reverse polarity such that a further actuation of the switch 58 will cause a lowering of the shutter 52. It will be appreciated that the feed-back control circuit illustrated may be attached to any roller blind construction. However it is advantageously combined with the cam profile 40 of a roller shutter assembly according to the invention, which provides benefits for rolling of a roller shutter having a slatted construction. The invention can be applied to office storage cabinets or other roller shutter arrangements and is not restricted to garage doors.

Claims: An improved roller shutter assembly comprising: a shutter comprising a plurality of linked slats; an elongate core; at each end of the core an end block (14) mounted for rotation about a carrying mounting block (16); each end block (14) being of a diameter larger than the elongate core and onto or off which the shutter is to be wound or unwound respectively; and in a space between the carrying mounting block (16) and end block (14), a coiled clock-type spring having opposite ends connected one to the end block (14) and the other to the carrying mounting block (16) so as to be tensioned by rotation of the end block (14) relative to the carrying mounting block (16) during winding or unwinding of the shutter; characterised in that each end block (14) is profiled to provide a peripheral cam surface (40) having a substantially radially disposed step (42), which steps (42) of the respective end blocks (14) are in alignment with one another so as to provide respective seats for an end slat of the shutter; and each carrying mounting block (16) has a spring loaded retractable mounting pin (22) received in a housing (24) provided in the carrying mounting block (16) such that the assembly may be removably mounted in a supporting bracket. An improved roller shutter assembly according to claim 1 characterised in that the elongate core is arranged to be rotated by way of a motor (56) and in that the assembly is further provided with a sensor (62) operative to sense resistance to unwinding of the shutter (52) and on sensing same, operative to stop rotation of the elongate core via switching (58,60) of the motor (56). An improved roller shutter assembly according to Claim 2, characterised in that the switching (58,60) of the motor is such as to automatically reverse the direction of the motor drive such that on its next operation the shutter (52) will be wound onto the core (50) and hence raised from its closed position. An improved roller shutter assembly according to claim 2 or 3, characterised in that a second sensor (66) is provided operative to detect the shutter (52) in its raised or fully wound position and prevent further rotation of the roller by switching of the motor.

Inventors: JACKSON JOHN, JACKSON, JOHN
Applicants: ROTALAC PLASTICS, ROTALAC PLASTICS LIMITED
Application year: 1991
Main classification: E06B9
IPC codes: E06B9