Geared motor unit for driving vehicle equipment and eliminating any axial play in a driveline

Abstract

The invention concerns a gear motor ( 1 ), in particular for driving vehicle equipment, comprising a rotor provided with a rotor shaft ( 6 ), a reduction gearbox housing ( 14 ) containing a cog wheel engaged in an endless screw of the shaft and capable of driving an output member ( 12 ). The invention is characterised in that it comprises means ( 12 ) for eliminating, under predetermined axial compression (F), all axial play between one end ( 6 a ) of the rotor shaft and the housing wall ( 13 ). Said means can comprise a plug ( 15 ) housed in the housing ( 14 ) end ( 13 ) and a piston ( 18 ), inserted between the plug ( 15 ) and the shaft ( 6 ) end ( 6 a ); the plug ( 15 ) exerts on the piston ( 18 ) and the shaft ( 6 ) the axial thrust ( 7 ) which is adjusted when being mounted, and is axially locked in the corresponding position by melting the housing ( 14 ) plastic material in the grooves or recesses ( 19 ) of the piston ( 18 ) surface, then in solidifying said plastic material. The suppression of axial play in the rotor shaft ( 6 ) eliminates all the disturbing noises caused by changes in rotational direction.

1 . Geared motor unit ( 1 ), particularly for driving vehicle equipment, comprising a rotor ( 5 ) equipped with a rotor shaft ( 6 ), a reduction gearbox ( 14 ) which contains a gearwheel ( 11 ) in mesh with a worm ( 9 ) belonging to the shaft and capable of driving an output member ( 12 ), and means ( 12 , . . . ) for eliminating, under a given compressive axial preload (F), any axial play between one end ( 6   a ) of the rotor shaft and the wall ( 13 ) of the box, characterized in that the said means comprise a plug ( 15 ) housed in the end ( 13 ) of the box ( 14 ), and a piston ( 18 ) inserted between the plug and the end of the shaft, the plug exerting the said compressive axial preload (F), set at the time of assembly, on the piston and on the shaft, and means ( 19 ) for immobilizing the piston in its axial position that corresponds to the said compressive preload.  
   
   
       2 . Geared motor unit according to  claim 1 , characterized in that the means for immobilizing the piston ( 18 ) in its axial position comprise irregularities ( 19 ) formed on the surface of the piston in contact with the wall ( 13   a ) of the box ( 14 ), such as grooves, the piston being made of metal, and the piston is immobilized with respect to the wall of the box by melting the plastic of which the box is made into the said roughnesses, either using ultrasound or using high-frequency welding.  
   
   
       3 . Geared motor unit, particularly for driving vehicle equipment, comprising a rotor ( 5 ) equipped with a rotor shaft ( 6 ), a reduction gearbox ( 14 ) which contains a gearwheel ( 11 ) in mesh with a worm ( 9 ) belonging to the shaft and capable of driving an output member ( 12 ), and means ( 12 , . . . ) for eliminating, under a given compressive axial preload (F), any axial play between one end ( 6   a ) of the rotor shaft and the wall ( 13 ) of the box, characterized in that the said means comprise a plug ( 37 ) housed in the end ( 35 ) of the box ( 13 ), which has a smooth surface and is immobilized in its axial position, compressed against the end ( 6   a ) of the shaft ( 6 ), by solidified adhesive ( 38 ) injected in the liquid state, at a given pressure, through a nozzle ( 39 ) of the box ( 14 ) behind the plug and filling that part of the housing ( 35 ) which is located behind the plug, which is immobilized in its axial position compressed against the end ( 6   a ) of the shaft ( 6 ) by the solidified adhesive ( 38 ).  
   
   
       4 . Geared motor unit according to  claim 1 , characterized in that the said means for immobilizing the piston comprise surface irregularities ( 23 ,  28 , . . . ) formed on the surface of the piston ( 22 ,  27 ) in contact with the wall ( 13   a ) of the box ( 14 ), at least one duct ( 25 ) arranged to the side of the piston in the wall of the box and opening into a chamber ( 26 ) of this wall, and hardened adhesive injected in the liquid state through this duct into the surface irregularities.  
   
   
       5 . Geared motor unit according to  claim 4 , characterized in that the said surface irregularities are notching, grooves or channels ( 23 ,  28 ) arranged on the peripheral surface of the piston ( 22 ,  27 ) in contact with the wall ( 13   a ) of the box ( 14 ).  
   
   
       6 . Geared motor unit, particularly for driving vehicle equipment, comprising a rotor ( 5 ) equipped with a rotor shaft ( 6 ), a reduction gearbox ( 14 ) which contains a gearwheel ( 11 ) in mesh with a worm ( 9 ) belonging to the shaft and capable of driving an output member ( 12 ), and means ( 12 , . . . ) for eliminating, under a given compressive axial preload (F), any axial play between one end ( 6   a ) of the rotor shaft and the wall ( 13 ) of the box, characterized in that arranged in the wall ( 13   a ) of the box ( 14 ) is a lateral nozzle opening into a counterbore formed around a plug, on the surface of which irregularities are formed, and in that adhesive injected in the liquid state through the nozzle and hardened by cooling, fills the roughnesses and counterbore and immobilizes the plug in the desired axial position so that it exerts the said compressive axial preload on the rotor shaft ( 6 ).