Axially Driven Piston/Cylinder Unit

Abstract

An axially driven piston/cylinder unit comprising a cylinder, a piston being movable between first and second piston positions in the axial direction of the cylinder, a fluid bearing between the piston and the cylinder and defining a bearing surface on the piston side enclosing said piston over a part of the axial length of the piston, and a drive element mechanically-connected to the piston by means of a piston rod. The piston rod is embodied to permit and compensate for a radial offset, or an inclination between the cylinder axis and the longitudinal axis, defining the movement direction of the drive element. The piston rod is provided with a first drive-side joint section, the piston rod is also provided with a second piston-side joint section and that the second piston-side joint section is provided in the rear region of the piston, away from the piston crown.

1 - 17 . (canceled)  
   
   
       18 . An axially driven piston-cylinder unit comprising: 
 a cylinder;    a piston which can be displaced back and forth in the axial direction of the cylinder between a first piston position, in which the cylinder volume enclosed by the piston and the cylinder is at a maximum, and a second piston position, in which this cylinder volume is at a minimum;    a fluid bearing provided between the piston and the cylinder, which bearing supports the piston in the cylinder so that it can be displaced axially and which determines a piston-side bearing surface surrounding the circumference of the piston, at least over a part of the axial extension of the piston;    a drive element that can be displaced back and forth in the axial direction of the cylinder or essentially in parallel with it, which element is connected mechanically to the piston by means of a piston rod;    wherein the piston rod is designed so that it permits, and compensates for, a radial offset or an inclination between the cylinder axis and the longitudinal axis determining the direction of movement of the drive element;    wherein the piston rod is provided with a first drive-side joint section, that the piston rod is provided with a second piston-side joint section and that the second piston-side joint section is provided in the rear region of the piston facing away from the piston crown.    
   
   
       19 . The axially driven piston-cylinder unit according to  claim 18 , wherein the second piston-side joint section is provided in the direction of the longitudinal axis of the piston at a point which is situated level with the rear region of the piston-side bearing surface.  
   
   
       20 . The axially driven piston-cylinder unit according to  claim 18 , wherein each joint section can be pivoted about at least one axis.  
   
   
       21 . The axially driven piston-cylinder unit according to  claim 20 , wherein each joint section can be pivoted about two axes which lie orthogonally relative to each other.  
   
   
       22 . The axially driven piston-cylinder unit according to  claim 20 , wherein each joint section has the displaceability of a ball and socket joint.  
   
   
       23 . The axially driven piston-cylinder unit according to  claim 18 , wherein the fluid bearing has a plurality of outlet nozzles for the fluid provided in the inner circumferential wall of the cylinder.  
   
   
       24 . The axially driven piston-cylinder unit according to  claim 18 , wherein the outlet nozzles are arranged so that when the piston is in its second piston position, first outlet nozzles supply the front region of the piston-side bearing surface relative to the longitudinal piston extension, and second outlet nozzles supply the central or rear region of the piston-side bearing surface relative to the longitudinal piston extension, with pressure fluid.  
   
   
       25 . The axially driven piston-cylinder unit according to  claim 18 , wherein the outlet nozzles are arranged so that when the piston is in its first piston position, the second outlet nozzles supply the front region of the piston-side bearing surface relative to the longitudinal piston extension, and third outlet nozzles supply the rear region of the piston-side bearing surface relative to the longitudinal extension, with pressure fluid.  
   
   
       26 . The axially driven piston-cylinder unit according to  claim 18 , wherein the fluid bearing is formed by a gas pressure bearing, preferably an air bearing, wherein the outlet nozzles are formed by gas outlet nozzles.  
   
   
       27 . The axially driven piston-cylinder unit according to  claim 18 , wherein a plurality of outlet nozzles each form nozzle devices.  
   
   
       28 . The axially driven piston-cylinder unit according to  claim 27 , wherein the nozzle devices are separated from each other in the axial direction of the piston-cylinder unit, and are preferably designed annularly about the cylinder axis.  
   
   
       29 . The axially driven piston-cylinder unit according to  claim 27 , wherein each nozzle device has a plurality of outlet nozzles separated from each uniformly in the circumferential direction.  
   
   
       30 . The axially driven piston-cylinder unit according to  claim 18 , wherein the outlet nozzles are formed by micro holes drilled by means of an energy-rich jet, which holes are preferably of a conical design, wherein their narrowest cross-section is located on the opening into the cylinder-side bearing surface.  
   
   
       31 . The axially driven piston-cylinder unit according to  claim 30 , wherein the micro holes are drilled by means of a laser jet.  
   
   
       32 . The axially driven piston-cylinder unit according to  claim 18 , wherein the pressure fluid for supplying the outlet nozzles is derived from a fluid flow compressed by compression of the cylinder volume.  
   
   
       33 . The axially driven piston-cylinder unit according to  claim 18 , wherein the piston is loaded by a displaceable drive element of a linear drive for the drive moving back and forth.  
   
   
       34 . A compressor for generating a pressure fluid and comprising: 
 an axially driven piston-cylinder unit including: 
 a cylinder;  
 a piston which can be displaced back and forth in the axial direction of the cylinder between a first piston position, in which the cylinder volume enclosed by the piston and the cylinder is at a maximum, and a second piston position, in which this cylinder volume is at a minimum;  
 a fluid bearing provided between the piston and the cylinder, which bearing supports the piston in the cylinder so that it can be displaced axially and which determines a piston-side bearing surface surrounding the circumference of the piston, at least over a part of the axial extension of the piston;  
 a drive element that can be displaced back and forth in the axial direction of the cylinder or essentially in parallel with it, which element is connected mechanically to the piston by means of a piston rod;  
   wherein the piston rod is designed so that it permits, and compensates for, a radial offset or an inclination between the cylinder axis and the longitudinal axis determining the direction of movement of the drive element;    wherein the piston rod is provided with a first drive-side joint section, that the piston rod is provided with a second piston-side joint section and that the second piston-side joint section is provided in the rear region of the piston facing away from the piston crown.