Rotary motor and a method for its manufacture

Abstract

The present invention relates to a rotary motor, preferably a pivot drive for construction machinery, trucks and the like comprising an elongate housing, preferably an approximately tubular housing, a piston displaceably received in the housing, which is axially displaceable by charging with a pressure medium in a pressure chamber, and a shaft received axially fixedly, but rotatably in the housing, with the piston being in screw engagement with the shaft and/or the housing. The invention furthermore relates to a method for the manufacture of such a rotary motor. The present invention departs from the previous approach of separating the sealing of the piston at the shaft and at the housing from the section effecting the rotary guide or the screw engagement. In accordance with the invention, a surface pair of piston and shaft and/or of piston and housing effecting the screw engagement can simultaneously form a sealing surface pair for the sealing of the pressure chamber for the charging of the piston with pressure. The same piston section simultaneously serves the transfer of torque and sealing. A considerably reduced construction length can hereby be achieved since the axial spacing between the sealing section and the rotary guide section or the screw engagement section of the piston is omitted. In addition, the respective components, in particular the housing and the shaft, can be manufactured in an endless manner and be produced as needed and in the required length.

1 . A rotary motor, preferably a pivot drive for construction machinery, trucks and the like, comprising an elongate housing ( 2 ), preferably an approximately tubular housing, at least one piston ( 10 ) displaceably received in the housing ( 2 ), which is axially displaceable by charging with a pressure medium in a pressure chamber ( 15 ,  16 ,  17 ,  18 ), and a shaft ( 3 ) received axially fixedly, but rotatably in the housing ( 2 ), with the piston ( 10 ) being in screw engagement with the shaft ( 3 ) and/or the housing ( 2 ), wherein a surface pair ( 8 ,  9 ;  11 ) of piston ( 10 ) and shaft ( 3 ) and/or of piston ( 10 ) and housing ( 2 ) effecting the screw engagement simultaneously forms a sealing surface pair for the sealing of the pressure chamber ( 15 ,  16 ,  17 ,  18 ) for the pressure charging of the piston ( 10 ). 
   
   
       2 . A rotary motor in accordance with  claim 1 , wherein the piston ( 10 ) has equally large effective piston surfaces on its two oppositely disposed sides for the pressure charging by the pressure chambers ( 15 ,  16 ,  17 ,  18 ). 
   
   
       3 . A rotary motor in accordance with  claim 1 , wherein the shaft ( 3 ) has a polygonal sectional cross-section differing from the circular shape in at least one screw engagement section ( 50 ) and is twisted spirally around its longitudinal axis. 
   
   
       4 . A rotary motor in accordance with  claim 1 , wherein the shaft ( 3 ) is made as winged shaft whose cross-section has at least one radially projecting wing-like yield nose ( 60 ), preferably two mutually oppositely disposed such yield noses ( 60 ), for the torque yield. 
   
   
       5 . A rotary motor in accordance with  claim 1 , wherein the shaft ( 3 ) has a circular cross-section, apart from the at least one yield nose ( 60 ), viewed in cross-section. 
   
   
       6 . A rotary motor in accordance with  claim 1 , wherein the outer diameter of the shaft ( 3 ) is larger in the region of the at least one yield nose ( 60 ) by at least 15%, preferably by approximately 25 to 50%, than the outer diameter of the shaft ( 3 ) in sections without a yield nose. 
   
   
       7 . A rotary motor in accordance with  claim 1 , wherein the shaft ( 3 ) has a substantially oval cross-section. 
   
   
       8 . A rotary motor in accordance with  claim 1 , wherein the shaft ( 3 ) is made as a hollow shaft and/or has an axial cut-out ( 61 ) in its interior for the supply and/or draining of the pressure medium. 
   
   
       9 . A rotary motor in accordance with  claim 1 , wherein a seal ( 12 ) is inserted into the inner jacket surface ( 11 ) of the piston ( 10 ) being in screw engagement with the shaft ( 3 ). 
   
   
       10 . A rotary motor in accordance with  claim 1 , wherein the piston ( 10 ) has an inner cut-out which forms a profile section substantially corresponding to the cross-section of the shaft ( 3 ). 
   
   
       11 . A rotary motor in accordance with  claim 1 , wherein the piston ( 10 ) is made as a wing piston whose cross-section at the outer periphery has at least one radially projecting yield nose ( 62 ), preferably two mutually oppositely disposed such yield noses ( 62 ), for the torque yield with respect to the housing ( 2 ). 
   
   
       12 . A rotary motor in accordance with  claim 11 , wherein the piston ( 10 ) has a contour corresponding to the flat side of an ellipse in a cross-sectional section without a yield nose ( 62 ). 
   
   
       13 . A rotary motor in accordance with  claim 1 , wherein the housing ( 2 ) has a cylindrical inner jacket surface differing from the circularly cylindrical shape, at which the outer jacket surface ( 13 ) of the piston ( 10 ) is guided and rotationally fixedly supported. 
   
   
       14 . A rotary motor in accordance with  claim 1 , wherein the housing ( 2 ) has a pressed-flat cross-section, preferably an approximately elliptical or oval cross-section. 
   
   
       15 . A rotary motor in accordance with  claim 1 , wherein the housing ( 2 ) has a cross-section whose outer contour differs from its inner contour. 
   
   
       16 . A rotary motor in accordance with  claim 1 , wherein the housing ( 2 ) is made as an extruded section and/or as an extrusion molded section. 
   
   
       17 . A rotary motor in accordance with  claim 1 , wherein the housing ( 2 ) is made as a compound housing which has a plurality of mutually connected shells set into one another. 
   
   
       18 . A rotary motor in accordance with  claim 17 , wherein the shells are made of different materials. 
   
   
       19 . A rotary motor in accordance with  claim 1 , wherein the compound housing comprises an inner shell in engagement with the piston ( 10 ) and an outer shell forming the outer envelope of the housing. 
   
   
       20 . A rotary motor in accordance with  claim 19 , wherein a support body, preferably of a foam material and/or of a cast material, which connects the outer shell to the inner shell, is provided between the inner shell and the outer shell. 
   
   
       21 . A rotary motor in accordance with  claim 1 , wherein a seal ( 14 ) is inserted into the outer jacket surface ( 13 ) of the piston ( 10 ) being in rotationally fixed engagement with the inner jacket surface of the housing ( 2 ). 
   
   
       22 . A rotary motor in accordance with  claim 1 , wherein the piston ( 10 ) is supported at the housing ( 2 ) and/or at the shaft ( 3 ) by plain bearings. 
   
   
       23 . A rotary motor in accordance with  claim 1 , wherein the piston ( 10 ) is supported at the housing ( 2 ) and/or at the shaft ( 3 ) by roller bearings ( 32 ;  41 ). 
   
   
       24 . A rotary motor in accordance with  claim 1 , wherein the twisted polygonal section of the shaft ( 3 ) has a uniform pitch over its length. 
   
   
       25 . A rotary motor in accordance with  claim 1 , wherein the twisted polygonal section of the shaft ( 3 ) has a pitch changing over the length of the shaft ( 3 ). 
   
   
       26 . A rotary motor in accordance with  claim 1 , wherein a plurality of pistons ( 10 ) are seated on the shaft ( 3 ) in screw engagement. 
   
   
       27 . A rotary motor in accordance with  claim 1 , wherein two pistons ( 10 ) to be moved in opposite senses are arranged on the shaft ( 3 ) and the shaft ( 3 ) and/or the housing ( 2 ) have screw engagement sections in opposite senses. 
   
   
       28 . A rotary motor in accordance with  claim 1 , wherein the shaft ( 3 ) is radially supported at a direction change section ( 49 ). 
   
   
       29 . A rotary motor in accordance with  claim 1 , wherein the shaft ( 3 ) is supported at a direction change section ( 49 ) and/or axially approximately centrally. 
   
   
       30 . A rotary motor in accordance with  claim 1 , wherein two pistons ( 10 ) or piston parts ( 10   a,    10   b ) biased axially with respect to one another are seated on the shaft ( 3 ). 
   
   
       31 . A rotary motor in accordance with  claim 1 , wherein a bias apparatus for the biasing of the two pistons ( 10 ) or piston parts ( 10   a,    10   b ) comprises a hydraulic pressure store between the two pistons ( 10 ) or piston parts ( 10   a,    10   b ) and/or can be fed by pressure medium from the pressure chambers ( 15 ,  16 ,  17 ,  18 ) for the actuation of the piston ( 10 ). 
   
   
       32 . A rotary motor in accordance with  claim 1 , wherein the two pistons ( 10 ) or piston parts ( 10   a,    10   b ) can be biased toward one another or apart from one another by a mechanical spring device ( 39 ). 
   
   
       33 . A rotary motor in accordance with  claim 1 , wherein the shaft ( 3 ) is supported by means of bearing covers ( 4 ) which are seated axially at end faces at the ends of the housing ( 2 ) and close the latter. 
   
   
       34 . A rotary motor in accordance with  claim 1 , wherein seals are provided between the bearing covers ( 4 ) and the shaft ( 3 ) for the sealing of the pressure chambers ( 15 ,  18 ), with the seal preferably being integrated in the bearing surface in each case at which the shaft ( 3 ) is rotatably supported at the bearing cover ( 4 ). 
   
   
       35 . A rotary motor in accordance with  claim 1 , wherein the shaft ( 3 ) is shaped from a substantially cylindrical shaft blank which has a polygonal sectional cross-section differing from the circular shape, the shaft blank is twisted in itself around its longitudinal axis by non-cutting shaping so that its outer contour forms a polygonal section twisted in itself. 
   
   
       36 . A method in accordance with  35 , wherein the shaft blank is twisted in opposite senses starting from a direction change section ( 49 ) toward oppositely disposed sides. 
   
   
       37 . A method in accordance with  claim 36 , wherein two shaft blanks twisted in opposite senses are rotationally fixedly connected to one another, preferably screwed to one another and/or welded to one another. 
   
   
       38 . Use of the rotary motor in accordance with  claim 1  for the pivoting of a loading board wall of a truck.