Neutral setting device for an adjustable hydraulic machine

Abstract

The invention relates to a neutral setting device of an adjustable hydraulic machine, in particular the adjustment of the neutral setting of a servo valve. The present invention relates in particular to servo adjustment devices with mechanically adjustable control pistons, wherein the necessary force can be applied mechanically, electromagnetically, pneumatically or hydraulically. The invention relates to a neutral setting device of an adjustable hydraulic machine with a housing in which a mounted input shaft is arranged, at which on one end a torque can be applied for turning the input shaft around an axis. On a second end a cylindrical extension is arranged eccentrically parallel to the axis. An adjustable control piston for opening and closing hydraulic fluid openings for application of pressure of a servo piston adjusts the hydraulic machine with respect to its delivery volume.

1 . A neutral setting device ( 1 ) of an adjustable hydraulic machine with a housing ( 2 ), in which are arranged:
 an input shaft ( 3 ) mounted in the housing ( 2 ) with a first end ( 3   a ), at which a torque can be applied for turning the input shaft ( 3 ) around an axis ( 23 ), and a second end ( 3   b ), at which a cylindrical extension ( 25 ) eccentrically parallel to the axis ( 23 ) is arranged,   an adjustable control piston ( 4 ) for opening and closing hydraulic fluid openings for application of pressure of a servo piston ( 24 ), which adjusts the hydraulic machine with respect to its delivery volume,   a lever ( 5 ), with a first end ( 5   a ) and a second end ( 5   b ) as well as with a bearing position ( 5   c ) arranged between the two ends ( 5   a,    5   b ), in which the cylindrical extension ( 25 ) of the input shaft ( 3 ) engages, wherein the first end ( 5   a ) of the lever ( 5 ) is connected in an articulated manner to the control piston ( 4 ) and the second end ( 5   b ) of the lever ( 5 ) is mounted in an articulated manner on a position feedback device ( 6 ), which transfers the position of the servo piston ( 24 ) to the lever ( 5 ),   a sliding part ( 8 ), which exhibits a planar face ( 8   a ) on one end, with which it is supported against a planar flattened portion ( 7   a ) on the input shaft ( 3 ), wherein the sliding part ( 8 ) is elastically prestressed perpendicular to the axis ( 23 ) of the input shaft ( 3 ) and is held by a guide element ( 10 ) in such a way that the sliding part ( 8 ) can be moved perpendicular to the axis ( 23 ) of the input shaft ( 3 ) relative to the guide element ( 10 ) and the planar face ( 8   a ) and the planar flattened portion ( 7   a ) in neutral position of the control piston ( 4 ) lie flat upon one another, characterized in that   the guide element ( 10 ) is supported vis-à-vis the housing ( 2 ) in such a way that the guide element ( 10 ) can be rotated in circumferential direction of the input shaft ( 3 ) relative to said shaft.   
     
     
         2 . The neutral setting device ( 1 ) according to  claim 1 , in which the guide element ( 10 ) through a setting screw ( 11 ) which is arranged perpendicular to the direction of movement of the sliding part ( 8 ) and perpendicular to the axis ( 23 ) of the input shaft ( 3 ) and which supports the guide element with one end ( 11   a ) vis-à-vis the housing ( 2 ) and engages in the guide element ( 10 ) in such a way that the guide element ( 10 ) is rotatable by turning the setting screw ( 11 ) in circumferential direction of the input shaft ( 3 ) relative to said shaft. 
     
     
         3 . The neutral setting device ( 1 ) according to  claim 2 , in which the end ( 11   a ) of the setting screw ( 11 ) in engagement with the guide element ( 10 ) is spherical and engages in a corresponding recess ( 10   a ) on the guide element ( 10 ) and supports itself in a groove ( 16 ) in the housing ( 2 ) which is constructed on an inside wall ( 13 ) of the housing ( 2 ) parallel to the axis ( 23 ). 
     
     
         4 . The neutral setting device ( 1 ) according to  claim 1 , in which the guide element ( 10 ) exhibits a pot-like bore into which the sliding part ( 8 ) is guided and upon whose floor area an elastic element ( 9 ) is supported, which prestresses the planar face ( 8   a ) of the sliding part ( 8 ) against the planar flattened portion ( 7   a ) on the input shaft ( 3 ). 
     
     
         5 . The neutral setting device ( 1 ) according to  claim 1 , in which the planar flattened portion ( 7   a ) is constructed on the input shaft ( 3 ) in a recess ( 7 ) of the input shaft ( 3 ). 
     
     
         6 . The neutral setting device ( 1 ) according to  claim 5 , in which the end of the sliding part ( 8 ) is constructed on the face ( 8   a ), providing with the recess ( 7 ) in the input shaft ( 3 ) an axial guide of the input shaft ( 3 ). 
     
     
         7 . The neutral setting device ( 1 ) according to  claim 1 , in which the input shaft ( 3 ) exhibits a circumferential groove ( 20 ) into which the guide element ( 10 ) engages with fork shaped ends ( 10   a,    10   b ), as a result of which the guide element ( 10 ) is connected to the input shaft ( 3 ) in an axially fixed manner. 
     
     
         8 . The neutral setting device ( 1 ) according to  claim 1 , in which the sliding part ( 8 ) exhibits an elastically mounted ball ( 28 ) on the end at which the planar face ( 8   a ) is constructed, said ball in neutral position of the control piston snapping into a corresponding recess ( 30 ) in the input shaft ( 3 ). 
     
     
         9 . The neutral setting device ( 1 ) according to  claim 1 , in which the hydraulic machine is integrated in a closed hydraulic circuit. 
     
     
         10 . The neutral setting device ( 1 ) according to  claim 1 , in which the input shaft ( 3 ) can be rotated mechanically or electromagnetically.