Positive-displacement machine

Abstract

A hydraulic positive-displacement machine includes at least two radially or axially spaced-apart groups of cylinder-piston units. The cylinders of the primary group can be made to communicate fluidically with cylinders of the secondary group via intermediate valves. At least two intermediate valves can be switched independently of one another.

1 . A hydraulic positive-displacement machine, comprising:
 at least two groups ( 1 ,  2 ) of cylinder-piston units ( 6   a,    6   b,    8   a,    8   b ) spaced apart radially or axially from one another, wherein cylinders ( 26   a ) of a primary group ( 1 ) of said at least two groups of cylinder-piston units are configured to communicate fluidically with cylinders ( 28   a ) of a secondary group ( 2 ) of said at least two groups of cylinder-piston units via intermediate valves ( 50 ), wherein at least of said two intermediate valves ( 50 ) are switchable independently of one another.   
     
     
         2 . The positive-displacement machine as defined by  claim 1 , wherein a number of cylinder-piston units ( 6   a,    6   b ) in said primary group ( 1 ) is equivalent to a number of cylinder-piston units ( 8   a,    8   b ) in said secondary group ( 2 ), and wherein cylinder heads ( 30   a,    32   a ) are secured in pairs on one another and are configured to communicate fluidically via an intermediate valve ( 50 ), and wherein all the intermediate valves ( 50 ) are switchable independently of one another. 
     
     
         3 . The positive-displacement machine as defined by  claim 1 , wherein each cylinder-piston unit ( 6   a,    6   b ) of said primary group ( 1 ) is activatable or deactivatable via an electrically or electrohydraulically actuated high-pressure valve and via an electrically or electrohydraulically actuated low-pressure valve ( 24   a,    24   b ). 
     
     
         4 . The positive-displacement machine as defined by  claim 1 , wherein said machine is a radial piston machine, wherein the cylinder-piston units ( 6   a,    6   b ) of the primary group ( 1 ) are located in a primary radial plane ( 1 ), and the cylinder-piston units ( 8   a,    8   b ) of the secondary group ( 2 ) are located in a secondary radial plane ( 2 ), and wherein the primary radial plane ( 1 ) and secondary radial plane( 2 ) are spaced apart from one another along an axis of rotation of a shaft ( 4 ). 
     
     
         5 . The positive-displacement machine as defined by  claim 2 , wherein the cylinder heads ( 30   a,    32   a ) are each located in pairs one after the other in an axial direction of the shaft ( 4 ). 
     
     
         6 . The positive-displacement machine as defined by  claim 1 , wherein said machine is an axial piston machine, wherein the cylinder-piston units of the primary group ( 1 ) are located on an inner circular cylinder, and the cylinder-piston units of the secondary group ( 2 ) are located on an outer circular cylinder. 
     
     
         7 . The positive-displacement machine as defined by  claim 1 , wherein the intermediate valves are unlockable check valves ( 50 ) embodied as seat valves, wherein a closing direction of each of said check valves is oriented from a cylinder ( 26   a ) of said primary group ( 1 ) to a cylinder ( 28   a ) of said secondary group ( 2 ). 
     
     
         8 . The positive-displacement machine as defined by  claim 7 , wherein said machine is a hydraulic motor, wherein a closing body ( 51 ) of each of said check valves ( 50 ), in a currentless basic position, blocks off a respective connecting conduit ( 46 ,  48 ) between cylinder heads ( 30   a,    32   a ), and in a position activated by a lifting magnet ( 54 ,  56 ), said closing body ( 51 ) of each of said check valves ( 50 ) uncovers a respective connecting conduit ( 46 ,  48 ). 
     
     
         9 . The positive-displacement machine as defined by  claim 8 , wherein each of said check valves ( 50 ) has a valve body ( 51 ,  52 ,  54 ), wherein a reciprocation direction of each said valve body is located approximately parallel to a shaft ( 4 ), and wherein the closing body ( 51 ) is located on one end portion of the valve body ( 51 ,  52 ,  54 ), and a magnet armature ( 54 ) of the lifting magnet ( 54 ,  56 ) is disposed on another end portion of the valve body ( 51 ,  52 ,  54 ). 
     
     
         10 . The positive-displacement machine as defined by  claim 9 , wherein each lifting magnet ( 54 ,  56 ) is located on a side of a secondary cylinder head ( 32   a ) remote from a primary cylinder head ( 30   a ), and wherein each valve body ( 51 ,  52 ,  54 ) has an intermediate portion, wherein said intermediate portion penetrates a work chamber of a respective secondary cylinder head. 
     
     
         11 . The positive-displacement machine as defined by  claim 3 , wherein the intermediate valves ( 50 ) are configured to switch more slowly than the high-pressure valves and the low-pressure valves ( 24   a,    24   b ). 
     
     
         12 . The positive-displacement machine as defined by  claim 1 , wherein the intermediate valves are proportional valves. 
     
     
         13 . The positive-displacement machine as defined by  claim 7 , wherein the cylinders ( 28   a ) of the secondary group ( 2 ) are larger than the cylinders ( 26   a ) of the primary group ( 1 ). 
     
     
         14 . The positive-displacement machine as defined by  claim 1 , wherein the cylinder-piston units ( 8   a,    8   b ) of the secondary group ( 2 ) have a larger idle volume than the cylinder-piston units ( 6   a,    6   b ) of the primary group ( 1 ).