Axial piston engine having an adjustment unit for electrically proportionally adjusting the supply volume

Abstract

The invention relates to an axial piston engine having a swash plate, or a bent axis with a valve segment, which can be adjusted by means of a servo piston, and having an adjustment unit for electrically proportionally adjusting the supply volume. The adjustment unit has a regulating piston for controlling the oil pressure which moves the servo piston, electrically actuable proportional magnets which act on the regulating piston, and a feedback device for feeding the instantaneous swash plate position or bent axis valve segment position back to the regulating piston. The feedback device has a tappet which is mechanically coupled to the swash plate or to the bent axis valve segment, in each case one leaf spring being arranged in the longitudinal direction at both sides of said tappet, said leaf springs enclosing a feedback lever which is mounted in the regulating piston.

1 . Axial piston engine having a swash plate, or a bent axis with a valve segment, which can be adjusted by means of a servo piston, and having an adjustment unit for electrically proportionally adjusting the supply volume, said adjustment unit having a regulating piston ( 2 ) for controlling the oil pressure which moves the servo piston, having electrically actuable proportional magnets ( 12 ,  12 ′) which act on the regulating piston ( 2 ), and a feedback device ( 1 ) for feeding the instantaneous swash plate position or bent axis valve segment position back to the regulating piston ( 2 ), the feedback device ( 1 ) having a tappet ( 9 ) which is mechanically coupled to the swash plate or to the bent axis valve segment, in each case one leaf spring ( 6 ,  6 ′) being arranged along each side of said tappet ( 9 ), said leaf springs enclosing a feedback lever ( 3 ) which is mounted in the regulating piston ( 2 ).  
   
   
       2 . Axial piston engine according to  claim 1 , in which the leaf springs ( 6 ,  6 ′) have a width and/or stiffness which varies, in particular continuously, in the longitudinal direction of the tappet ( 9 ).  
   
   
       3 . Axial piston engine according to  claim 1 , in which one end of the feedback lever ( 3 ) is mounted in a ball guide ( 8 ) in the regulating piston ( 2 ), and the feedback lever head ( 4 ), which is situated opposite said end, of the feedback lever ( 3 ) is clamped between the leaf springs ( 6 ,  6 ′).  
   
   
       4 . Axial piston engine according to  claim 1 , in which the leaf springs ( 6 ,  6 ′) extend along the tappet ( 9 ) and beyond its end ( 10 ), and between them, at their ends, form a space for holding the feedback lever ( 3 ).  
   
   
       5 . Axial piston engine according to  claim 2 , in which the leaf springs ( 6 ,  6 ′) are fastened to the tappet ( 9 ) by means of in each case at least one setting screw ( 13 ,  13 ′), by means of which in each case one preload, with which the leaf springs ( 6 ,  6 ′) act on the feedback lever ( 3 ), can be set, said preload defining a dead band.  
   
   
       6 . Axial piston engine according to  claim 5 , in which the width and/or stiffness of the leaf springs ( 6 ,  6 ′) vary in the longitudinal direction of the tappet in the direction of the feedback lever ( 3 ) in such a way that a desired dead band can be obtained.  
   
   
       7 . Axial piston engine according to  claim 6 , in which the dead band of each leaf spring ( 6 ,  6 ′) can be set individually.  
   
   
       8 . Axial piston engine according to  claim 7 , in which the tappet ( 9 ) has screw-on faces ( 16 ,  16 ′) on the tappet ( 9 ), said screw-on faces ( 16 ,  16 ′) forming a contact surface for fastening the leaf springs ( 6 ,  6 ′) by means of fastening screws ( 14 ,  14 ′), and a gap ( 15 ,  15 ′), by means of which the preloads of the leaf springs ( 6 ,  6 ′) can be set using the setting screws ( 13 ,  13 ′).  
   
   
       9 . Axial piston engine according to  claim 3 , in which the feedback lever head ( 14 ) is spherical or cylindrical.  
   
   
       10 . Axial piston engine according to  claim 1 , in which the engagement point of the feedback lever ( 3 ) in the regulating piston ( 2 ) is situated outwith the central longitudinal axis ( 17 ) of the latter.  
   
   
       11 . Axial piston engine according to  claim 1 , in which the engagement point of the feedback lever ( 3 ) in the regulating piston ( 2 ) is situated on the longitudinal axis of actuating elements which are actuated by the proportional magnets ( 12 ,  12 ′).  
   
   
       12 . Axial piston engine according to  claim 1 , in which the regulating piston ( 2 ) has a longitudinal bore ( 18 ) through which leakage oil can be discharged.  
   
   
       13 . Type series of axial piston engines according to  claim 1  having different supply volumes, with all the models of said type series being provided with the same adjustment unit.