Device for transmitting motion between the rotor of a synchronous permanent-magnet motor and the working part, having an increased free rotation angle

Abstract

A device for transmitting motion between the rotor of a synchronous permanent-magnet motor and the working part, having an increased free rotation angle, which comprises at least two motion transmission couplings which mutually cooperate in a kinematic series. Each coupling is constituted by at least one driving element which is eccentric with respect to the rotation axis and is rigidly coupled to a first component of the motion transmission system and by at least one driven element, which is also eccentric with respect to the rotation axis and is rigidly coupled to the component arranged kinematically after the preceding one. The angle covered by the elements of each coupling is, as a whole, less than a round angle. The intermediate components of the kinematic transmission have both a driven element and a driving element for receiving the motion from the preceding one and transmitting it to a subsequent one.

1. A device for transmitting motion between the  a rotor of a synchronous permanent-magnet motor and the  a working part, comprising  comprising:
 at least two motion transmission couplings which mutually cooperate in a kinematic series,  series;  
 eacha first coupling being constituted byof said motion transmission couplings comprising at least one driving element which is eccentric with respect to the rotation axis and is rigidly coupled to a component of the motion transmission system and bythe rotor, and at least one driven element,  which is also eccentric with respect to the rotation axis and is rigidly coupled to the component arranged kinematically after the preceding one,and can rotate freely with respect to said rotor; 
 a second coupling of said motion transmission couplings comprising at least one driving element which is eccentric with respect to the rotation axis and at least one driven element which is also eccentric with respect to the rotation axis and is rigidly coupled to the working part, 
 wherein the angle covered by the elements of each coupling beingis, as a whole, less than a round angle, the intermediate components of the kinematic transmission having both a driven element and a driving element for receiving the motion from a preceding one and transmitting it to a subsequent one, 360 °,  
 wherein said at least one driving element of the second coupling comprises said at least one driven element of said first coupling; 
 wherein said motion transmission couplings are toothed,  
 a first one of said couplings being constituted by two first teeth which arethe first coupling comprising at least one driving tooth which is eccentric with respect to the rotation axis and is rigidly coupled to the rotor, of a motor in diametrically opposite positions, and of two second teeth which are rigidly coupled, likewise in diametrically opposite positions, to an annular element whichrotor, and at least one driven tooth which is also eccentric with respect to the rotation axis and can rotate freely with respect to said rotor,the working part; 
 a second one of said couplings being composed of said second teeth and of two thirds teeth which are also diametrically opposite and arethe second coupling comprising at least one driving tooth, which is eccentric with respect to the rotation axis and can rotate freely with respect to the working part and by at least one driven tooth which is also eccentric with respect to the rotation axis and is rigidly coupled to the working partpart, and wherein a radial clearance is provided between the at least one driven tooth of the second coupling and the at least one driving tooth of the first coupling.  
 
     
     
       2. The device according to  claim 1 , comprising four couplings which mutually cooperate in a kinematic series, a  the first one of said couplings being constituted by  comprising a first tooth which is rigidly coupled to the  a free shaft of a motor  the rotor and of  by a second tooth which is rigidly coupled to an annular element which can rotate freely with respect to said free shaft, a second one of said couplings being composed of  comprising said second tooth and of  a third tooth which is rigidly coupled to the working part,  part; a third one of said couplings being composed of  comprising a fourth tooth which is rigidly coupled to the rotor of said motor and of  a fifth tooth which is rigidly coupled to an annular element which moves  can rotate freely with respect to said free axis  shaft, a fourth one of said couplings being composed of  comprising said fifth tooth and of  a sixth tooth which is rigidly coupled to said free shaft. 
     
     
       3. The device according to claim  2    22 , wherein two of  said four  motion transmission couplings are arranged in an axial hollow body which protrudes from  is rigidly coupled to said working part toward said rotor  and is closed by a cover. 
     
     
       4. The device according to  claim 3 , wherein said first tooth protrudes from a tang which is keyed to the end of said free shaft, said first tooth being arranged eccentrically with respect to said shaft and constituting a driving tooth for said second tooth which protrudes axially from an annular element which can rotate freely in said hollow body with respect to said shaft and said hollow body, said second tooth having an extension adapted to make contact with said first tooth and with said third tooth which protrudes from the internal wall of the hollow body, the other two of said four motion transmission couplings comprising said fourth tooth, which is rigidly coupled to an axial tang which protrudes from a tip flange of the rotor of said motor, so as to surround said free shaft, said annular element from which said fifth tooth protrudes being arranged so that it can rotate freely, the extension of said fifth tooth being adapted to make contact with said fourth tooth and with said sixth tooth which protrudes from another annular element which is rigidly coupled to said shaft. 
     
     
       5. The device according to  claim 2 , wherein said cover closes said hollow body so that a hermetic seal is provided therein. 
     
     
       6. The device according to  claim 2 , wherein in said hollow body there is a viscous fluid which has lubricating, impact-damping and noise-deadening functions. 
     
     
       7. The device according to claim  1    23 , wherein said motion transmission couplings are arranged in an axial hollow body which is rigidly coupled to said working part and is closed by a cover. 
     
     
       8. The device according to claim  7    3 , wherein said first tooth protrudes from a tang which is keyed on the end of said  a free shaft of the rotor, said first tooth being arranged eccentrically with respect to said free  shaft and constituting  comprising a driving tooth for said second tooth which protrudes axially from an annular element which can rotate freely in said hollow body with respect to said free  shaft and to said hollow body, said second tooth having an extension which allows it to make contact with said first tooth and with said third tooth which protrudes from an internal wall of the hollow body. 
     
     
       9. The device according to  claim 8 , wherein said first tooth has a radial extension which partially affects an integral  internal space of said hollow body, the radial extension of said second tooth affecting a region between said tang and an external wall of said hollow body, providing clearances which allow free movement, said second tooth having an axial extension for making contact with said first tooth and with said third tooth, said third tooth protruding radially from the internal wall of said hollow body towards an  in the vicinity of the external profile of said first tooth. 
     
     
       10. The device according to  claim 7 , wherein said first tooth protrudes from a tang which is keyed to  on the end of said  a shaft of the rotor, said first tooth being arranged eccentrically with respect to said shaft and constituting a driving tooth for said second tooth which protrudes axially from an annular element which can rotate freely in said hollow body with respect to said shaft and to said hollow body, said second tooth having an extension adapted  which allows it to make contact with said first tooth and with said third tooth which protrudes axially from the face of  said cover which  from a position which is proximate to the outer profile of the face that is directed toward the inside of the hollow body. 
     
     
       11. The device according to  claim 10 , wherein said first tooth has a radial  limited axial extension which partially affects an  in the internal space of said hollow body, the radial extension of said second tooth affecting a region between said tang and an external wall of said hollow body, providing clearances which allow free movement,  said second tooth having an axial extension adapted  which allows it to make contact with said first tooth and with said third tooth, said third tooth protruding radially from a position which is proximate to an external profile of the cover towards an external profile of said annular element  being such that it cannot make contact with said first tooth but only with said second tooth. 
     
     
       12. The device according to claim  1    22 , wherein said motion transmission couplings comprise a first tooth which is rigidly coupled to an axial tang which protrudes from a tip  head flange of said rotor, said annular element from which said second tooth protrudes being arranged so as to surround said  a shaft of said rotor and so that it can rotate freely, the extension of said second tooth being such that it can make contact with said first tooth and with said third tooth which protrudes from another annular element which is rigidly coupled to said shaft. 
     
     
       13. The device according to  claim 12 , wherein the axial extension of said first tooth partially affects the extension of said tang, a remaining part being affected by said annular element, from which said second tooth protrudes. 
     
     
       14. The device according to  claim 12 , wherein said third tooth occupies a radial space provided externally with respect to said first tooth. 
     
     
       15. The device according to  claim 1 , wherein said couplings are arranged in an axial hollow body which is rigidly coupled to said working part and is closed hermetically by a cover. 
     
     
       16. The device according to  claim 15 , wherein said two first teeth protrude in a diametrically mutually opposite configuration from a first annular element which is keyed to the shaft of a motor, said first teeth radially and partially affecting a space inside said hollow body, said first teeth constituting driving teeth for said two second teeth which protrude axially from a second annular element which can rotate freely in said hollow body with respect to said shaft and to said hollow body, said second teeth having an extension adapted to make contact also with two third teeth which protrude radially from the internal wall of said hollow body in a region left free by said first teeth. 
     
     
       17. The device according to  claim 16 , wherein said first teeth are arranged in axially offset positions and in that said second teeth are shaped so as to have parts whose radial extension affects all of the region between said tang and the external wall of the hollow body, providing clearances which allow free movement, said second teeth having an axial extension adapted to make contact with said first teeth and with said third teeth which protrude radially from the internal wall of said hollow in axially offset positions. 
     
     
       18. The device according to  claim 1 , wherein at least one of said teeth is composed of an internal supporting part which is made of rigid plastics  and of  two mutually opposite  external parts which are overmolded on the internal part, are  made of elastomeric material, and form the surfaces for contact with the other teeth . 
     
     
       19. The device according to  claim 1 , wherein a slight interference is provided between mutually moving parts of said couplings, producing a friction engagement. 
     
     
       20. The device according to  claim 1 , wherein said working part is an impeller with curved vanes of a centrifugal pump. 
     
     
       21. The device according to  claim 1 , comprising two couplings which mutually cooperate in a kinematic series, the first one of said couplings comprising a first tooth which is rigidly coupled to the rotor of the motor and by a second tooth which is rigidly coupled to an annular element which can rotate freely with respect to said rotor; a second one of said couplings comprising said second tooth and a third tooth which is rigidly coupled to the working part. 
     
     
       22. The device according to  claim 1 , comprising two couplings which mutually cooperate in a kinematic series, the first one of said couplings comprising two first teeth which are rigidly coupled to the rotor of the motor in diametrically opposite positions, and two second teeth which are rigidly coupled, likewise in diametrically opposite positions, to an annular element which can rotate freely with respect to said rotor; a second one of said couplings comprising said second teeth and two third teeth which are also diametrically opposite and are rigidly coupled to the working part.