Clutch between a rotary output drive shaft for a cutting device, a rotary cutter and cutting device provided with said clutch

Abstract

A clutch between the rotary output drive shaft of a cutting device and a rotary cutter includes a rotor which is connected to the drive shaft and whose at least one part of the internal walls forms a friction track and a stator which bears the cutter and is driven by the rotor by pivotable friction shoes. The shoes are spring-loaded and supported by the stator, each pivotable shoe being also mounted with clearance on the plate in such a way that it is angularly displaceable between two end positions, i.e. of the clutch engaging and disengaging positions. The clutch is characterized in that the transition from the engaging position to the disengaging position is carried out during the stator deceleration by relative displacement of the shoe and the stator for compressing a second spring which brings back the shoe from the angular disengaging position to the angular engaging position.

1 . A coupler ( 1 ) between a rotary output drive shaft of a cutting device and a rotary cutting unit ( 2 ), said coupler ( 1 ) comprising:
 a rotor ( 3 ) which can be rendered integral with a drive shaft, the rotor having a form of a cylindrical body or a bell, the rotor having at least some internal walls of which form a friction track ( 4 ); and   a stator ( 5 ) which can support the cutting unit ( 2 ), the stator ( 5 ) being configured to be driven by the rotor ( 3 ) via friction blocks ( 6 ) which are supported by the stator ( 5 ), each friction block ( 6 ) being fitted on a block-holder plate of the stator ( 5 ), and is free to pivot around an axis which is parallel to an axis of rotation of the stator ( 5 ), being subjected permanently to an action of at least a first compression spring ( 12 ) with generally radial force, in order to be applied to the friction track ( 4 ) of the rotor ( 3 ) and to rotate the stator ( 5 ), the blocks ( 6 ) also being fitted with play on said plate in order to be able to be displaced angularly between two extreme positions, a first position being of engagement in which a friction surface between the blocks ( 6 ) and the cylindrical body or bell is maximal, and a second position being of disengagement in which the friction surface between the blocks ( 6 ) and the cylindrical body or bell is minimal, and facilitates sliding of the blocks ( 6 ) on a surface of the friction track ( 4 ) of the rotor ( 3 ) and, during slowing down or stoppage of the stator ( 5 ), the blocks ( 6 ) and the stator ( 5 ) are driven under an action of the rotor ( 3 ) by relative displacement, for a purpose of passage from the engaged position to the disengaged position, this displacement giving rise to compression of a second spring ( 13 ), this second spring ( 13 ) tending to return the blocks ( 6 ) from an angular disengaged position to an angular engaged position,   wherein the block-holder plate comprises two circular flanges ( 7 ,  8 ) which are connected to one another by a hub ( 9 ), in order to delimit an inner peripheral circular groove, within which both the blocks ( 6 ) and the springs are accommodated, the blocks ( 6 ) having a shape of fingers pivoting around an axis parallel to an axis of the hub, and the springs ( 12 ,  13 ) have axes intersecting at a support point of the block.   
     
     
         2 . The coupler ( 1 ) according to  claim 1 , wherein each friction block ( 6 ) mounted with play on the block-holder plate is designed to move in a plane perpendicular to the axis of rotation of the stator ( 5 ) during passage from the engaged position into the disengaged position or vice versa, following a direction that forms an angle (a) in a range of [60-85°] with a radius of the stator ( 5 ) passing through a pivoting axis ( 14 ) of said friction blocks ( 6 ). 
     
     
         3 . The coupler ( 1 ) according to  claim 1 , wherein a pivoting axis ( 14 ) and receiving bearings ( 15 ) of the pivoting axis ( 14 ), which allow freely-pivoting mounting of the friction blocks ( 6 ) on the block-holder plate, are carried: one by the friction blocks ( 6 ) and the other by a support plate of the friction blocks ( 6 ) and have noncomplementary shapes to allow relative angular displacement between the friction blocks ( 6 ) and the support plate of the friction blocks ( 6 ). 
     
     
         4 . The coupler ( 1 ) according to  claim 3 , wherein the bearings ( 15 ) of the pivoting axis ( 14 ) each have a form of an oblong hole made in the friction blocks ( 6 ), said oblong holes being crossed by a shaft mounted stationary on the block-holder plate, the shaft mounted stationary on the block-holder plate being parallel to the axis of rotation of the stator ( 5 ) comprising the pivoting axis ( 14 ) of said friction blocks ( 6 ). 
     
     
         5 . The coupler ( 1 ) according to  claim 4 , wherein the longitudinal axis of each hole that comprises a guide path forms an angle in a range of [60-85] with a radius of the stator passing through the pivoting axis ( 14 ) of the friction blocks ( 6 ). 
     
     
         6 . The coupler according to  claim 1 , wherein the block-holder plate is provided with a plurality of housings ( 11 A,  11 B) for receiving the spring ( 12 ) to modify a relative position between the springs ( 12 ,  13 ) acting on the same friction blocks ( 6 ) so as to vary a re-engagement time corresponding to passage from the disengaged position to the engaged position of said friction blocks ( 6 ). 
     
     
         7 . The coupler ( 1 ) according to  claim 1 , wherein the springs ( 12 ,  13 ) acting on the friction blocks ( 6 ) are helicoidal compression springs, with axes intersecting at a support point of the friction blocks ( 6 ) on the friction lining of the cylindrical body in the disengaged position of said friction blocks ( 6 ). 
     
     
         8 . The coupler ( 1 ) according to  claim 1 , wherein the friction blocks include at least three friction blocks ( 6 ) and the springs include at least six springs ( 12 ,  13 ), each friction block ( 6 ) having a shape of a curved pin provided on its ends with bulges ( 6 A,  6 C), a recess arranged between said bulges used to receive one of the bulges ( 6 A,  6 C). 
     
     
         9 . The coupler ( 1 ) according to  claim 2 , wherein the pivoting axis ( 14 ) and receiving bearings ( 15 ) of the pivoting axis ( 14 ), which allow freely-pivoting mounting of friction blocks ( 6 ) on the block holder plate, are carried: one by the friction blocks ( 6 ) and an other by the block holder plate and have noncomplementary shapes to allow relative angular displacement between the friction blocks ( 6 ) and the block holder plate. 
     
     
         10 . The coupler according to  claim 2 , wherein the block-holder plate is provided with a plurality of housings ( 11 A,  11 B) for receiving the spring ( 12 ) to modify a relative position between the springs ( 12 ,  13 ) acting on the friction blocks ( 6 ) so as to vary a re-engagement time corresponding to passage from the disengaged position to the engaged position of said friction blocks ( 6 ). 
     
     
         11 . The coupler according to  claim 3 , wherein the block-holder plate is provided with a plurality of housings ( 11 A,  11 B) for receiving the spring ( 12 ) to modify a relative position between the springs ( 12 ,  13 ) acting on the friction blocks ( 6 ) so as to vary a re-engagement time corresponding to passage from the disengaged position to the engaged position of said friction blocks ( 6 ). 
     
     
         12 . The coupler according to  claim 4 , wherein the block-holder plate is provided with a plurality of housings ( 11 A,  11 B) for receiving the spring ( 12 ) to modify a relative position between the springs ( 12 ,  13 ) acting on the friction blocks ( 6 ) so as to vary a re-engagement time corresponding to passage from the disengaged position to the engaged position of said friction blocks ( 6 ). 
     
     
         13 . The coupler according to  claim 5 , wherein the block-holder plate is provided with a plurality of housings ( 11 A,  11 B) for receiving the spring ( 12 ) to modify a relative position between the springs ( 12 ,  13 ) acting on the friction blocks ( 6 ) so as to vary a re-engagement time corresponding to passage from the disengaged position to the engaged position of said friction blocks ( 6 ). 
     
     
         14 . The coupler ( 1 ) according to  claim 2 , wherein the springs ( 12 ,  13 ) acting on the friction blocks ( 6 ) are helicoidal compression springs with axes intersecting at a support point of the friction blocks ( 6 ) on the friction lining of the cylindrical body in the disengaged position of said friction blocks ( 6 ). 
     
     
         15 . The coupler ( 1 ) according to  claim 3 , wherein the springs ( 12 ,  13 ) acting on the friction blocks ( 6 ) are helicoidal compression springs with axes intersecting at a support point of the friction blocks ( 6 ) on the friction lining of the cylindrical body in the disengaged position of said friction blocks ( 6 ). 
     
     
         16 . The coupler ( 1 ) according to  claim 4 , wherein the springs ( 12 ,  13 ) acting on the friction blocks ( 6 ) are helicoidal compression springs with axes intersecting at a support point of the friction blocks ( 6 ) on the friction lining of the cylindrical body in the disengaged position of said friction blocks ( 6 ). 
     
     
         17 . The coupler ( 1 ) according to  claim 5 , wherein the springs ( 12 ,  13 ) acting on the friction blocks ( 6 ) are helicoidal compression springs with axes intersecting at a support point of the friction blocks ( 6 ) on the friction lining of the cylindrical body in the disengaged position of said friction blocks ( 6 ).