AU743887B2 - Clutch mechanism for manual roller door operation - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

TO BE COMPLETED BY APPLICANT 00 *0 Name of Applicant: SCOTT NICHOLSON *s* Actual Inventor: SCOTT NICHOLSON Address for Service: Barker Blenkinship Associates Patent Attorneys PO Box 34, CHATSWOOD NSW 2067 Invention Title: CLUTCH MECHANISM FOR MANUAL ROLLER DOOR OPERATION 00* Details of Associated Provisional Application No: PP0996 18 December 1997 00 The following statement is a full description of this invention, including the best method of performing it known to me:i~ CLUTCH MECHANISM FOR MANUAL ROLLER DOOR

OPERATION

The present invention relates to a clutch mechanism to facilitate manual operation of roller doors or shutters which are normally motor driven.

000 o* Soo Roller doors and shutters are in widespread use in connection with warehouses, factories, garages and many other applications and such roller doors and shutters are typically motor driven by electric motors.

In the event of power failures, fire or other unforseen eventualities the motor driven feature of roller and/or shutter doors may not be operable and it is consequently desirable and indeed mandatory in many o• applications that manual operation of the doors and/or shutters may be readily achieved independently of the motorised feature. Manual operation of such doors is often achieved by way of an endless chain extending about an overhead chain pulley wheel in turn journalled on an overhead shaft engagable with the shaft about which the roller door or shutter is wound; the chain extending down to an area adjacent ground level whereat it may be pulled by an operator in order to rotate the wheel and shaft and hence the door.

If the chain is to permanently reside on the chain pulley wheel then the chain pulley wheel cannot rotate during ordinary powered operation of jfi the door or shutter having regard to the fact that the high rpm occasioned by motorised operation would cause derailment. It is therefore desirable that a clutch be present in the door mechanism in order that the chain pulley wheel only be engaged with the shaft when the door is to be manually operated.

ooo0 Various such clutch mechanisms have been proposed to date although •most of these are inconvenient to operate or expensive to manufacture.

oo00 0 0 It is accordingly an object of the present invention to provide a clutch to facilitate engagement of a chain pulley wheel with the main shaft about which a roller door is rolled when it is intended to manually operate the door. Alternatively it is an object of the present invention to provide the market with a fUrther choice of product.

0 0 0 *00 According to the present invention there is provided a clutch mechanism adapted to facilitate manual operation of a motorised roller door or shutter comprising a chain pulley wheel journalled for rotation about the axis of a first shaft permanently engaged with or common with the main shaft about which the door or shutter is stored but not constrained to rotate with the first shaft at times when such shaft is motor driven; a clutch disc journalled alongside the chain pulley wheel on the same axis similarly free to rotate independently of the first shaft; linking means to link the chain pulley wheel to the clutch disc such that rotation of one L~ili~lii:l i causes rotation of the other about their common axis; biasing means to bias the linking means into an equilibrium linked position such that the abovementioned link between clutch disc and chain pulley wheel is operative; the biasing means being sufficiently weak that a light tug on the chain about the chain pulley wheel will cause the linking means to disengage to the extent that the chain pulley wheel may rotate to at least a small extent without co-extensive rotational movement of the clutch disc; a driven disc interposed between the chain pulley wheel and the clutch disc and keyed to the first shaft so as to preclude independent rotation of the driven disc with respect to the shaft; a drive pawl mounted to the clutch disc about a pivot on the disc at a point non-concentric with the axis about which the clutch disc rotates; the pawl being linked at one point removed from the pivot with a part of the chain pulley wheel and being adapted for movement, under the influence of such link, about its pivot from a disengaged position whereat it does not contact or lock against the driven disc to an engaged position whereat it directly or indirectly locks into the driven disc thereby causing the driven disc, clutch disc and pulley wheel to rotate as one; the link between the chain pulley wheel and pawl being such that with the clutch wheel and pulley wheel in their equilibrium position under the influence of the biasing means the pawl adopts its disengaged position with respect to the driven disc whereas the drive pawl moves about its pivot to its engaged position with respect to the driven disc whenever a pull exerted by the chain on

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the pulley wheel overcomes the biasing means which maintains the equilibrium position between the clutch disc and the chain pulley wheel.

One embodiment of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a perspective view of a chain pulley wheel in accordance with the present invention; Figure 2 is a side elevation of a clutch disc and associated pawl mechanism in accordance with the present invention; Figure 3 is a perspective view of a driven disc in accordance with the present invention; Figure 4 is a schematic representation of a roller door motor, manual operating chain and operator in accordance with the present invention; and Figure 5 is an exploded view of the components of figures 1, 2 and 3 hereof indicating their inter-relationship.

Figure 1 depicts a chain pulley wheel 1 being adapted for journalling about a shaft (not shown) along its central axis 2 by means of bearings 3.

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The wheel is provided with a central groove 4 adapted to receive a chain (not shown) and having transverse bulkheads 5 in the groove 4 in order to prevent slippage of the chain (not shown). It will also be observed that one side of the pulley carries a projecting spring pin 6 adjacent a peripheral portion and at a point one hundred and eighty degrees •removed from the spring pin a drive pin 7 of similar configuration. #too •o.o.r ,With reference now to figure 2 there is disclosed a clutch disc 8 adapted S•to be joumrnalled on the same shaft (not shown) as the above described chain pulley wheel. The clutch disc is similarly provided with a central axis 2 and bearings 3 in order that it may be journalled about such shaft (not shown). The clutch disc is intended to be mounted alongside the chain pulley wheel with the face of the clutch disc depicted in figure 2 adjacent the face of the chain pulley wheel depicted in figure 1 with the ,spring pin 6 of the chain pulley wheel adapted to lie between springs 9 and 10 mounted on upstanding flange 11 on the face of clutch disc 8. It will be observed that the space between springs 9 and 10 defines a passage 12 in which spring pin 6 may lie.

One hundred and eighty degrees removed from the springs 9 and 10 and passage 12 is drive pawl 13 comprising a substantially circular plate centrally mounted to the clutch disc about pivot pin 14. Drive pawl 13 is provided with slot 15 adapted to accept drive pin 7 of chain pulley wheel 1 and is further provided with drive wheel 16 mounted thereto about secondary pivot pin 17.

Figure 3 depicts a driven disc 18 intended to be mounted about its central aperture 19 on the same shaft as chain pulley wheel 1 and clutch disc 8 although in the case of driven disc 18 the disc is positively mounted to the shaft and locked thereto by way of a key (not shown) in keyway

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S"The inter-relationship between the chain pulley wheel of figure 1, the clutch disc of figure 2 and the driven disc of figure 3 is best illustrated by reference to figure 5 wherein the shaft 21 is depicted upon which the three components are located. It will be appreciated that the shaft is the end of the motor shaft with the motor (not shown) lying to the left of plate 22 depicted in figure 5. The positioning of the motor 30 with respect to the roller door 23 and roller door drum 24 is depicted in figure 4. The chain for manual operation 25 and operator 26 are also depicted in figure 4. With reference again to figure 5 it will be observed that the chain pulley wheel 1 is configured at its left-hand extremity as a drum 27 which when assembled onto shaft 21 actually houses and hides driven wheel 18 and clutch disc 8. It will be appreciated that the smaller diameter of the driven wheel 18 with respect to both the clutch disc 8 and the drum 27 of the chain pulley wheel 1 permits driven disc 18 to be interposed between the clutch disc and the chain pulley wheel.

-I In use the springs 9 and 10 attached to flange 11 bias spring pin 6 on chain pulley wheel 1 to an equilibrium fixed position with respect to the clutch disc and hence the two wheels normally sit in a fixed relationship with each other with drive pin 7 captivated within slot 15 and the drive pawl thereby maintained at the position depicted in figure 2 with drive o* 6 wheel 16 not engaged with arcuate drive pockets 28 disposed around the o**o internal peripheral portions of external peripheral flange 29 on the driven oo -disc 18. The clutch disc and chain pulley wheel maintain this relationship -o-S irrespective of whether or not the motor is turning shaft 21 having regard to the fact that there are bearings 3 interposed between both these components and shaft 21.

It is only when a rotating force is exerted at the peripheral portions of 6* go6 chain pulley wheel 1 by the chain pulling against bulkheads 5 that spring pin 6 urges against one of springs 9 or 10 (depending upon the direction *of rotation). The resilient deformation of one of springs 9 or 10 allows relative rotation between the clutch disc and chain pulley wheel such that drive pin 7 on the chain pulley wheel will cause rotation of drive pawl 13 about its pivot pin 14. This rotation brings drive wheel 16 out towards the peripheral portions of the clutch disc and more importantly into engagement with driven pockets 28 on driven disc 18. Once drive wheel 16 is in engagement with one of arcuate driven pockets 28 further rotational forces being exerted on the chain pulley wheel by the chain will result in rotation of shaft 21 having regard to the fact that driven disc 18 is keyed thereto. Manual operation of the roller door is thereby facilitated.

It should be appreciated that the locking of drive wheel 16 into one of the arcuate driven pockets 28 not only locks the clutch disc to the driven disc 18 but also the clutch disc is still constrained to spin with the pulley oo .oo wheel having regard to the link between the two which is created by

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drive pin 7 being captivated within slot It will be appreciated that once the driving force on chain pulley wheel 1 ceases due to the operator 26 ceasing to pull on chain 25 the restorative S•action of either spring 9 or spring 10 will cause spring pin 6 to once again oo o So adopt its equilibrium position within passage 12 between springs 9 and 0...9010 and hence cause drive pin 7 to move drive pawl 13 back into the position depicted in figure 2 whereat it is no longer engaged via drive wheel 16 to driven disc 18.

At the equilibrium position motorised operation of the door may be once again activated without rotating either clutch disc 8, chain pulley wheel 1 or chain 25 having regard to the fact that at the equilibrium position the driven disc is no longer in engagement with drive wheel 16 or the clutch disc.

More positive pawl arrangements may be devised other than that depicted with reference to figure 2 hereof as it will be appreciated that excessive torque applied to the chain pulley wheel could cause circular drive wheel 16 to jump from one arcuate driven pocket to an adjacent o *o driven pocket. The arrangement depicted is however intended to prevent damage to the system or danger to a person adjacent the chain in the event that the chain is inadvertently pulled thereby applying torque to the chain pulley wheel during motorised operation of the door. In the case of such an unintentional engagement of the clutch it will be appreciated that rotation of drive wheel 16 and the jumping of drive wheel 16 from one S•driven pocket to adjacent driven pockets will tend to cause less damage to the system and a less positive engagement of the clutch disc to the driven disc than would be the case if for example a pawl and ratchet system were utilised.

It will be appreciated that alternate embodiments apart from that above described may be devised without departing from the scope and intendment of the present invention. For example it should be obvious that differing shaped drive pawls may be utilised and for example the drive pawl (and associated drive pin 7 on the chain pulley wheel) do not need to be one hundred and eighty degrees removed from springs 9 and about the clutch disc.

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Claims (4)

1. A clutch mechanism adapted to facilitate manual operation of a motorised roller door or shutter comprising a chain pulley wheel journalled for rotation about the axis of a first shaft permanently engaged with or common with the main shaft about which the door or shutter is stored but not constrained to rotate with the first shaft S at times when such shaft is motor driven; a clutch disc journalled alongside the chain pulley wheel on the same axis and similarly free to rotate independently of the first shaft; linking means to link the chain pulley wheel to the clutch disc such that rotation of one causes rotation of the other about their common axis; biasing means to bias the linking means into an equilibrium linked position; the biasing means being sufficiently weak that a light tug on the chain about the chain pulley wheel will allow limited relative rotational movement of the chain pulley wheel relative to the clutch disc out of the equilibrium linked position; a driven disc interposed between the chain pulley wheel and the clutch disc and keyed to the first shaft so as to preclude independent rotation of the driven disc with respect to the shaft; a drive pawl mounted to the clutch disc about a pivot on the disc at a point non-concentric with the axis about which the clutch disc rotates; the pawl being linked at one point removed from the pivot with a part of the chain pulley wheel and being adapted for movement, under the influence of such link, about its pivot from a disengaged position whereat it does not contact or lock against the driven disc to an engaged position whereat it directly or indirectly locks into the driven disc thereby causing the driven disc, clutch disc and pulley wheel to rotate as one; the link between the chain pulley wheel and pawl being such that with the clutch wheel and pulley wheel in their .•°°:equilibrium position under the influence of the biasing means the S: pawl adopts its disengaged position with respect to the driven disc 0 whereas the drive pawl moves about its pivot to its engaged position with respect to the driven disc whenever a pull exerted by the chain on the pulley wheel overcomes the biasing means which S•maintains the equilibrium position between the clutch disc and the chain pulley wheel. o:o oi

2. A clutch mechanism in accordance with claim 1 hereof wherein the linking means to link the chain pulley wheel to the clutch disc comprises a protrusion upstanding from one of said components adapted to be captivated in a void defined by two resiliently deformable members on the face of the opposing component; the resiliently deformable members being adapted to bias the protrusion to an equilibrium position between two resiliently deformable members and to permit only limited lateral movement of the protrusion with respect to the resiliently deformable I- members hence limiting relative rotational movement between the two components.

3. A clutch mechanism in accordance with claim 1 hereof wherein the link between the chain pulley wheel and the pawl comprises a pin upstanding from the face of the pulley wheel and adapted to be captivated in a substantially radial slot in the pawl. C

4. A clutch mechanism in accordance with claim 1 hereofwherein the driven disc is provided with an upstanding flange facing the chain pulley wheel the radially internal surface of which comprises a series of arcuate drive pockets; the pawl having a drive wheel journalled on a pin upstanding therefrom and having a radius such °o that it may be received in one of the arcuate driven pockets on the flange of the driven disc when urged into such pockets by rotation of the drive wheel in turn occasioned by limited relative rotational movement of the chain pulley wheel with respect to the clutch disc; the engagement of the drive wheel with an arcuate drive pocket serving to lock the pulley wheel, driven disc and clutch disc together thereby preventing relative rotational movement of same. A clutch mechanism in accordance with claim 1 hereof wherein the link between the chain pulley wheel and the pawl and the position on the pawl adapted to engage with the driven disc are at least one 14 hundred and twenty degrees removed from each other about the pivot point of the pawl. DATED this 4 t1h day of December 1998. SCOTT NICHOLSON see* by his Patent Attorneys 0*0" Barker Blenkinship Associates V* S .6-9:0