Device for and method of height adjustment of seat with a drive motor

Abstract

A device for height adjustment of a vehicle seat has a drive motor, transmissions having different lifting strokes and operating synchronously, one of the transmissions reaching an abutment earlier than the other of the transmissions, a housing provided for the transmissions and having abutment surfaces, and an abutment surface arranged so that at reaching a maximum position of a vehicle seat a transmission housing element abuts against the abutment surface so that a braking moment which exceeds a drive moment of the drive motor is produced.

1 . A device for height adjustment of a vehicle seat, comprising a drive motor; transmissions having different lifting strokes and operating synchronously, one of said transmissions reaching an abutment earlier than the other of said transmissions; a housing provided for said transmissions and having abutment surfaces; and an abutment surface being arranged so that at reaching a maximum position of a vehicle seat a transmission housing element abuts against said abutment surface so that a braking moment which exceeds a drive moment of said drive motor is produced.  
     
     
         2 . A device as defined in claim  1 ; and further comprising a threaded sleeve which receives a threaded spindle of one of said transmissions; and an abutment surface which is located at an end side opposite to said threaded sleeve.  
     
     
         3 . A device as defined in  claim 2 , wherein said threaded sleeve has a base region provided with force receiving location.  
     
     
         4 . A device as defined in  claim 3 , wherein said force receiving location is formed in an outer tooth set which cooperates with a worm drive.  
     
     
         5 . A device as defined in  claim 1 , wherein an abutment of said housing element against said abutment surface is performed by deformation of said housing element over a tensioning path s.  
     
     
         6 . A device as defined in  claim 2 , wherein a contact location between said abutment surface and said housing element is provided at a radius with respect to an axis of symmetry of said threaded spindle.  
     
     
         7 . A method of blocking a drive moment with which two transmissions are driven synchronously and produced different lifting strokes, comprising the steps of providing abutments at a housing of one of the transmission to define a maximum positions; and producing by a contact of a deformable housing element with an abutment surface a braking moment which exceeds a drive moment of a threaded spindle.  
     
     
         8 . A method as defined in claim  7 ; and further comprising deforming the housing element by abutting an abutment surface of a bearing flange against the abutment of one transmission housing.  
     
     
         9 . A method as defined in claim  7 ; and further comprising providing a contact region between surfaces which produce the braking moment at a radius r with respect to an axis of symmetry, which is selected so that the braking moment exceeds the drive moment.  
     
     
         10 . A method as defined in claim  7 ; and further comprising providing in a contact region between the surfaces which produce the braking moment, coatings which increase friction.