Patent Publication Number: US-2004043853-A1

Title: Clutch arrangement using idler means

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to a clutch arrangement. More particularly, the clutch arrangement of the present invention is intended for use in circumstances involving a drive and driven shaft, and the effective transmission of power therebetween.  
       BACKGROUND ART  
       [0002] Many items of machinery employ a drive shaft and driven shaft arrangement. In circumstances where the driven shaft carries a heavy weight there is often the need for a clutch arrangement to be provided between the driven and drive shafts to enable initial drive to be transferred effectively to the driven shaft and to prevent damage to the drive shaft and any engine or motor associated therewith upon discontinuance of drive.  
       [0003] As an example, a driven shaft on which is mounted a rotor in a threshing machine may generate a large momentum during operation. If the drive motor is cut during operation the momentum of the thresher rotor will continue to rotate the driven shaft on which it is mounted and potentially cause damage to the drive shaft and the engine associated therewith if there is no clutch arrangement provided therebetween.  
       [0004] Many existing clutch arrangements rely on an idler wheel that impinges on a belt running between a drive pulley and a driven pulley. The idler wheel often impinges upon the belt in a direction causing the belt to bend in a manner for which it was not designed. For example, most belts are constructed and designed to bend in one direction only. If an idler wheel is to impinge upon the belt in the other direction this tends to weaken the belt. In addition, many existing clutch arrangements can cause over-extension of the belt, this again weakening the belt.  
       [0005] The clutch arrangement of the present invention has as one object thereof to overcome substantially, or at least provide a useful alternative to, the above problems associated with the prior art.  
       [0006] The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia as at the priority date of the application.  
       [0007] Throughout this specification, unless the context requires otherwise, the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers  
       DISCLOSURE OF THE INVENTION  
       [0008] In accordance with the present invention there is provided a clutch arrangement characterised by an idler means and an actuating means, the idler means further comprising a guide wheel, a pivotal mounting and an idler wheel, the idler wheel being arranged so as to impinge upon a belt or the like transferring drive between at least two pulleys or the like, wherein the idler means and actuating means are arranged such that the guide wheel is engaged with or abutting the actuating means, movement in the actuating means inducing movement in the idler means about the pivotal mounting by way of the guide wheel.  
       [0009] Preferably, the actuating means further comprises a flat portion and a ramped portion, the guide wheel being able to pass along both the ramped and flat portions. Movement of the guide wheel along the flat portion of the actuating plate preferably does not induce pivotal movement in the idler means and consequently the idler wheel, as does movement of the guide wheel along the ramped portion.  
       [0010] The actuating means is preferably slidably supported on a support member. Further, the actuating means has provided therein a guide slot through which is received a remotely mounted guide member. The actuating means preferably has provided thereon a mounting means for a hydraulic or pneumatic ram.  
       [0011] Preferably, the idler means is mounted within the belt or the like such that the idler wheel impinges on the belt or the like in an outward direction.  
       [0012] The idler wheel is preferably rotatably mounted on an idler plate, the idler plate being mounted on the pivotal mounting in a pivotal manner. The guide wheel is preferably mounted on an arm which is also mounted on the pivotal mounting in a pivotal manner.  
       [0013] The idler plate and arm may be independently pivotal about the pivotal mounting to a point in rotation at which the arm impinges upon the idler plate and induces movement therein. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014] The clutch arrangement of the present invention will now be described, by way of example only, with reference to one embodiment thereof and the accompanying drawings, in which:— 
     [0015]FIG. 1 is a side elevational view of a clutch arrangement in accordance with the present invention, shown in position between a drive pulley and a driven pulley of a rotor thresher machine in a substantially ‘slack’ or only partially engaged position; and  
     [0016]FIG. 2 is a side elevational view of the clutch arrangement of FIG. 1, in a “tight” or engaged position. 
    
    
     Best Mode(s) For Carrying Out the Invention  
     [0017] In FIGS. 1 and 2 there is shown a clutch arrangement  10  in position on a thresher rotor machine  12 , the machine  12  being shown only in part. The thresher rotor machine  12  comprises an end plate  14  through which projects a drive shaft  16  and a rotor or driven shaft  18 . The drive shaft  16  has provided thereabout a drive pulley  20 . The driven shaft  18  has provided thereabout a driven pulley  22 .  
     [0018] A belt  24  is provided in known manner about the drive pulley  20  and driven pulley  22 . Drive is imparted from the drive pulley  20  to the driven pulley  22  through the belt  24 . A level of adjustment in the fit of the belt  24  about the pulleys  20  and  22  is provided by way of a slot  26  provided in the end plate  14 .  
     [0019] The clutch arrangement  10  comprises an Idler means, for example an idler plate  28  and an actuating means, for example an actuating plate  30 . The idler plate  28  is provided with a pivotal mounting  32  to the end plate  14 . The idler plate  28  is of generally triangular configuration, the pivotal mounting  32  being provided in one corner thereof, a stub axial  34  being provided in another corner thereof, the remaining corner thereof being cut-away to accommodate a guide wheel  36  which is rotatably mounted on an arm  38  extending from the pivotal mounting  32 . The guide wheel  36  is supported by the arm  38  in a manner such that the guide wheel  36  is positioned within the cut-away of the idler plate  28 . The stub axial  34  supports rotatably thereon an idler wheel  40 . The idler wheel  40  is arranged such that rotation or pivotal movement of the idler plate  28  about the pivotal mounting  32  allows the idler wheel  40  to be moved into and out of forceful engagement with the belt  24 .  
     [0020] The actuating plate  30  comprises in part a guide slot  42 , through which is received a guide member  44 . The actuating plate  30  further comprises a ramped portion  46  and a flat portion  48 , the portions  46  and  48  being contiguous. Still further, the actuating plate  30  comprises a skid  50  at a lower end thereof, the skid  50  further having a mounting means  52  depending therefrom. The skid  50  is supported on a support member  54 , the support member  54  being mounted upon the end plate  14 .  
     [0021] A mounting member or point  56  is provided on the end plate  14  in a position such that a hydraulic or pneumatic ram (not shown) may be mounted therebetween, movement in the ram causing movement of the actuating plate  30  with respect to both the idler means and support member  54 .  
     [0022] The support member  54  and the pivotal mounting  32  of the idler plate  28  are arranged such that the guide wheel  36  engages the ramped portion  46  or the flat portion  48  of the actuating plate  30 , in use. The guide member  44 , in combination with the guide slot  42  in the actuating plate  30 , defines the limits of travel of the actuating plate  30  relative to the idler plate  28 .  
     [0023] Actuation of the ram induces movement in the actuating plate  30  which is guided by its support on the support member  54  and its engagement with the guide member  44  such that it moves between the drive pulley  20  and the driven pulley  22  in a direction dependent upon whether an operator (not shown) desires that the clutch arrangement  10  be engaged or disengaged from the belt  24 .  
     [0024] Movement of the actuating plate  30  towards the driven pulley  22  causes the guide wheel  36  to ride upwardly along the ramped portion  46 . This motion causes the idler plate  28  to pivot about the mounting means  32  and pushes the idler wheel  40  into firm engagement with the belt  24 , thereby ensuring drive is efficiently imparted from the drive pulley  20  to the driven pulley  22 , as shown in FIG. 2.  
     [0025] Beyond the ramped portion  46  the guide wheel  36  passes onto the flat portion  48  of the actuating plate  30 . The flat portion  48  ensures that no further rotation of the idler plate  28  is induced and prevents over-extension of the belt  24 . This process is simply reversed to disengage the idler wheel  40  from the belt  24  through rotation of the idler plate  28  about the mounting means  32  as the guide wheel  36  passes down the ramped portion  46  of the actuating plate  30 .  
     [0026] In light of the foregoing, the clutch arrangement  10  of the present invention can be seen to provide an arrangement in which an idler wheel impinges upon a belt in a preferred direction and consequently avoids weakening of the belt. Further, the present clutch arrangement should not cause over-extension of the belt, again avoiding weakening the belt.  
     [0027] Further, the clutch arrangement  10  of the present invention provides an arrangement able to accommodate use in machinery in which large momentum is generated during use and avoiding damage that may result to the drive shaft and the engine associated therewith.  
     [0028] Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.