Variable capacity hydrostatic axial piston machine

Abstract

The invention relates to a variable capacity hydrostatic axial piston machine having a drive shaft which has a drive flange having an end face oriented towards displacement pistons in which end face spherical shells for holding substantially spherical piston heads are formed. The calotte of the spherical shells in this case go beyond the semisphere and each have a circular opening with a smaller diameter than the spherical shell diameter. The spherical calotte of the piston heads have a recess having a smaller diameter than that of the circular opening of the spherical shells so that at the vertex of the piston a spherical section making up less than the semisphere and, spaced apart from the latter by the recess a retaining collar having a larger diameter than the circular opening of the spherical shells are formed. A transverse groove is formed in the circular openings of the spherical shells in such a way that the piston head with the retaining collar can be threaded into the spherical shell through the transverse groove and is retained there in the working position of the piston.

1 . Variable capacity hydrostatic axial piston machine having a drive shaft ( 1 ) which has a drive flange ( 2 ) having an end face ( 3 ) oriented towards displacement pistons ( 4 ) in which end face spherical shells ( 5 ) for holding substantially spherical piston heads ( 6 ) are formed:
 the calotte of the spherical shells ( 5 ) going beyond the semi sphere and each having a circular opening ( 7 ) with a smaller diameter than the spherical shell diameter;   the spherical calotte of the piston heads ( 6 ) having a recess ( 8 ) having a smaller diameter than that of the circular opening ( 7 ), so that at the vertex ( 13 ) of the piston, a spherical section ( 9 ) making up less than the semisphere and spaced apart from the latter by the recess ( 8 ), a retaining collar ( 10 ) having a larger diameter than the circular opening ( 7 ) of the spherical shells ( 5 ) are formed; and   a transverse groove ( 11 ) being formed in the circular openings ( 7 ) of the spherical shells ( 5 ) in such a way that the piston head ( 6 ) with the retaining collar ( 10 ) can be threaded into the spherical shell ( 5 ) through the transverse groove ( 11 ) and is retained there in the working position of the piston ( 4 ).   
   
   
       2 . Axial piston machine according to  claim 1 , in which the retaining collar ( 10 ) forms a spherical layer which begins approximately in the central plane of the spherical dome of the piston heads ( 6 ). 
   
   
       3 . Axial piston machine according to  claim 1 , in which the retaining collar ( 10 ) forms a spherical layer which extends approximately from the central plane of the spherical dome beyond the latter by about ⅛ to ¼, preferably about ⅙ of the sphere diameter. 
   
   
       4 . Axial piston machine according to  claim 1 , in which the recess ( 8 ) is rotationally symmetrical in relation to the piston longitudinal axis ( 19 ). 
   
   
       5 . Axial piston machine according to  claim 1 , in which the transverse grooves ( 11 ) of the spherical shells form a circular ring around the axis of the drive shaft ( 1 ). 
   
   
       6 . Axial piston machine according to  claim 1 , in which, in order to thread them into the spherical shells ( 5 ) the pistons ( 6 ) can be set at an angle (α) to the end face ( 3 ) of the drive flange ( 2 ) which is smaller than the smallest such angle occurring during the operation of the axial piston pump. 
   
   
       7 . Axial piston machine according to  claim 6 , in which mounting grooves ( 12 ) are provided in the end face ( 3 ) of the drive flange ( 2 ) which make threading possible at a minimum angle (α) between the piston longitudinal axis ( 19 ) and the end face ( 3 ) of the drive flange ( 2 ). 
   
   
       8 . Axial piston machine according to  claim 1 , in which the pistons ( 6 ) have a bore ( 20 ) in the longitudinal direction through which hydraulic pressure is led from the cylinder chamber to the spherical section ( 9 ) of the piston head ( 6 ) for the purpose of balancing the hydrostatic load on the mounting. 
   
   
       9 . Axial piston machine according to  claim 8  in which in order to limit the hydrostatic balancing force a circumferential groove ( 14 ) is formed in the spherical section ( 9 ) of the piston head ( 6 ) and is surrounded on the outside by an annular spherical layer as a sealing surface ( 15 ). 
   
   
       10 . Axial piston machine according to  claim 9  in which a spiral groove ( 16 ) is formed in the spherical section ( 9 ) of the piston head ( 6 ) from the bore ( 20 ) as far as the circumferential groove ( 14 ).