Cylinder means of single acting type with a return function and method of operating the same

Abstract

An energy-saving method and an energy-saving device for operating a single-acting cylinder device provided with a return function, which comprises a cylinder part ( 2 ) with an interior duct ( 50 ) and a piston ( 4 ) which is arranged in a movable manner in the duct ( 50 ) and which defines a working chamber ( 5 ) and a return chamber ( 6 ) in the duct ( 50 ). The piston ( 4 ) executes a working stroke and a return stroke in the duct. The method of operating the cylinder device comprises the steps of causing a first fluid to flow into the working chamber ( 5 ) from a pressure source ( 39 ), which has an output pressure, and thereby operating the working stroke of the piston ( 4 ), closing the return chamber ( 6 ), so that a second fluid in the return chamber ( 6 ) is compressed during the working stroke of the piston, and opening the working chamber ( 5 ) after the working stroke, so that the first fluid is permitted to flow out of the working chamber ( 5 ) to the atmosphere and the second fluid compressed in the return chamber ( 6 ) returns the piston ( 4 ) during the return stroke. By reducing the pressure of the second fluid in the return chamber ( 6 ) if this pressure exceeds an upper pressure value, which is the pressure reached first of either the output pressure of the pressure source ( 39 ) or a maximum pressure value, which corresponds to a maximum permissible pressure in the return chamber ( 6 ) during operation, the building up of an undesirable pressure in the return chamber ( 6 ) is avoided.

1 . A method of in an energy-saving way operating a single-acting cylinder device provided with a return function, which comprises a cylinder part ( 2 ) with an interior duct ( 50 ) and a piston ( 4 ) arranged in a movable manner in the duct ( 50 ), said piston defining a working chamber ( 5 ) and a return chamber ( 6 ) in the duct ( 50 ) and executing a working stroke and a return stroke in the same, the method comprising the steps of 
 causing a first fluid to flow into the working chamber ( 5 ) from a pressure source ( 39 ), which has an output pressure, and thereby operating the working stroke of the piston ( 4 ),    closing the return chamber ( 6 ), so that a second fluid in the return chamber ( 6 ) is compressed during the working stroke of the piston ( 4 ), and    opening the working chamber ( 5 ) after the working stroke, so that the first fluid is permitted to flow out of the working chamber ( 5 ) into the atmosphere and so that the second fluid compressed in the return chamber ( 6 ) returns the piston ( 4 ) during the return stroke, characterised by the step of    reducing the pressure of the second fluid in the return chamber ( 6 ) if this pressure exceeds an upper pressure value, which is the pressure reached first of either the output pressure of the pressure source ( 39 ) or a maximum pressure value, which corresponds to a maximum permissible pressure in the return chamber ( 6 ) during operation.    
     
     
         2 . A method as claimed in    claim 1   , wherein the return chamber ( 6 ) is opened via a nonreturn valve unit ( 32 ) if the pressure of the second fluid in the return chamber ( 6 ) exceeds the output pressure of the pressure source ( 39 ) counteracting the nonreturn valve unit ( 32 ), so that the piston ( 4 ) is prevented from executing a return stroke in case of a sudden pressure drop of the pressure source ( 39 ) or an undesired pressure rise in the return chamber ( 6 ).  
     
     
         3 . A method as claimed in    claim 1    or    2   , wherein the second fluid is caused to flow out of the return chamber ( 6 ) via a high-pressure regulator unit ( 33 ) at least as long as the pressure of the second fluid in the return chamber ( 6 ) exceeds the maximum pressure value, which is settable.  
     
     
         4 . A method as claimed in    claim 3   , wherein the high-pressure regulator unit ( 33 ) is closed when the pressure of the second fluid in the return chamber ( 6 ) is on a level with the maximum pressure value.  
     
     
         5 . A method as claimed in any one of the preceding claims, wherein the flow resistance of the first fluid is controlled so as to be lower out of the working chamber ( 5 ) than into the same.  
     
     
         6 . A method as claimed in any one of the preceding claims, wherein the second fluid is caused to flow into the return chamber ( 6 ) via a low-pressure regulator unit ( 34 ) at least as long as the pressure in the return chamber ( 6 ) is lower than a minimum pressure value, which corresponds to a minimum acceptable pressure in the return chamber ( 6 ) during operation.  
     
     
         7 . A method as claimed in    claim 6   , wherein the low-pressure regulator unit ( 34 ) is closed when the pressure of the second fluid in the return chamber ( 6 ) is on a level with the minimum pressure value.  
     
     
         8 . An energy-saving cylinder device of single-acting type with a return function, comprising a cylinder part ( 2 ) with an interior duct ( 50 ) and a piston ( 4 ) arranged in a movable manner in the duct ( 50 ), said piston defining a working chamber ( 5 ) in the duct ( 50 ) for a first fluid and a return chamber ( 6 ) for a second fluid and executing a working stroke and a return stroke, and a control unit ( 30 ) for controlling the flow of the first fluid between a pressure source ( 39 ), which has an output pressure, and the cylinder part ( 2 ), characterised in that the control unit has a pressure regulator device ( 30 ′) which is connected to the return chamber ( 6 ) and arranged to reduce the pressure of the second fluid in the same if this pressure exceeds an upper pressure value, which is the pressure-reached first of either the output pressure of the pressure source ( 39 ) or a maximum pressure value, which corresponds to a maximum permissible pressure in the return chamber ( 6 ) during operation.  
     
     
         9 . A cylinder device as claimed in    claim 8   , wherein the pressure regulator device ( 30 ′) comprises a nonreturn valve unit ( 32 ), which is connected to the return chamber ( 6 ) and the pressure source ( 39 ) and is arranged to open and release the second fluid from the return chamber ( 6 ) at least as long as the pressure of the second fluid in the return chamber ( 6 ) exceeds the output pressure of the pressure source ( 39 ) counteracting the nonreturn valve unit ( 32 ), so that the piston ( 4 ) is prevented from executing a return stroke in case of a sudden pressure drop of the pressure source ( 39 ) or an undesired pressure rise in the return chamber ( 6 ).  
     
     
         10 . A cylinder device as claimed in    claim 8    or    9   , wherein the pressure regulator device ( 30 ′) comprises a high-pressure regulator unit ( 33 ), which is connected to the return chamber ( 6 ) and which is arranged to open and release the second fluid from the return chamber ( 6 ) at least as long as the pressure of the second fluid in the return chamber ( 6 ) exceeds the maximum pressure value, which is settable.  
     
     
         11 . A cylinder device as claimed in    claim 10   , wherein the high-pressure regulator unit ( 33 ) is arranged to close the return chamber ( 6 ) when the pressure of the second fluid in the return chamber ( 6 ) is on a level with the maximum pressure value.  
     
     
         12 . A cylinder device as claimed in any one of claims  8 - 11 , wherein the pressure regulator device ( 30 ′) comprises a low-pressure regulator unit ( 34 ), which is connected to the return chamber ( 6 ) and a fluid source ( 39 ) and which is arranged to open and introduce fluid into the return chamber ( 6 ) at least as long as the pressure of the second fluid in the same is lower than a minimum pressure value, which corresponds to a minimum acceptable pressure in the return chamber ( 6 ) during operation.  
     
     
         13 . A cylinder device as claimed in    claim 12   , wherein the low-pressure regulator unit ( 34 ) is arranged to close the return chamber ( 6 ) when the pressure of the second fluid in the return chamber ( 6 ) is on a level with the minimum pressure value.  
     
     
         14 . A cylinder device as claimed in any one of claims  8 - 13 , wherein the control unit ( 31 ) communicates with the working chamber ( 5 ) and is arranged to control the first fluid to and from the working chamber ( 5 ), such that the flow resistance of the first fluid is lower out of the working chamber ( 5 ) than into the same.  
     
     
         15 . A cylinder device as claimed in any one of claims  8 - 14 , wherein the cylinder part ( 2 ) comprises an elongated casing ( 3 ), which on the inside defines said duct ( 50 ), and at least one end wall portion ( 7 ,  8 ) which is arranged to close the duct ( 50 ) in an associated end of the casing ( 3 ), and wherein the casing ( 3 ) on the outside of the duct ( 50 ) comprises an elongated, double-wall portion which defines at least one expansion chamber ( 20 ,  21 ,  22 ,  23 ) which is in fluid communication with the return chamber ( 6 ).  
     
     
         16 . A cylinder device as claimed in    claim 15   , wherein each expansion chamber ( 20 ,  21 ,  22 ,  23 ) is in fluid communication with the return chamber ( 6 ) via at least one duct ( 40 ) in the end wall portion ( 7 ,  8 ).  
     
     
         17 . A cylinder device as claimed in    claim 16   , wherein at least two expansion chambers ( 20 ,  21 ,  22 ,  23 ) are in fluid communication with the return chamber ( 6 ) and with each other via at least one duct ( 40 ) in the end wall portion ( 7 ,  8 ) to minimise the flow resistance of the second fluid.  
     
     
         18 . A cylinder device as claimed in    claim 15   , wherein each expansion chamber ( 20 ,  21 ,  22 ,  23 ) is in fluid communication with the return chamber ( 6 ) via an end wall chamber (not shown) in the end wall portion ( 7 ,  8 ).  
     
     
         19 . A cylinder device as claimed in    claim 18   , wherein at least two expansion chambers ( 20 ,  21 ,  22 ,  23 ) are in fluid communication with the return chamber ( 6 ) and with each other via the end wall chamber (not shown) in the end wall portion ( 7 ,  8 ).  
     
     
         20 . A cylinder device as claimed in any one of claims  15 - 19 , wherein a second end wall portion ( 8 ) is arranged to close the duct ( 50 ) in a second associated end of the casing ( 3 ).  
     
     
         21 . A cylinder device as claimed in    claim 20   , wherein the second end wall portion ( 8 ) defines an end wall chamber (not shown) which is in fluid communication with the return chamber ( 6 ), preferably via said at least one expansion chamber ( 20 ,  21 ,  22 ,  23 ) in the casing ( 3 ).  
     
     
         22 . A cylinder device as claimed in    claim 20    or    21   , wherein the double-wall portion ( 3 ′,  3 ″) of the casing ( 3 ) defines at least two expansion chambers ( 20 ,  21 ,  22 ,  23 ), which both are in fluid communication with the return chamber ( 6 ) via at least one duct ( 40 ) or end wall chamber in the first end wall portion ( 7 ) and which are in fluid communication with each other via at least one duct ( 41 ) or end wall chamber in the second end wall portion ( 8 ).  
     
     
         23 . A cylinder device as claimed in any one of claims  20 - 22 , wherein the double-wall portion ( 3 ′,  3 ″) of the casing ( 3 ) defines at least two separate expansion chambers ( 20 ,  21 ,  22 ,  23 ), and wherein one expansion chamber ( 20 ,  21 ,  22 ,  23 ) is in fluid communication with the return chamber ( 6 ) via at least one duct ( 40 ) in the first end wall portion ( 7 ) and the other expansion chamber ( 20 ,  21 ,  22 ,  23 ) is in fluid communication with the working chamber ( 5 ) via at least one duct ( 41 ) in the second end wall portion ( 8 ) to permit an inversion of the function of the return chamber ( 6 ) and the working chamber ( 5 ).