Screw spindle pump arrangement

Abstract

A screw spindle pump arrangement includes a low-pressure connection, a high-pressure connection, a drive spindle, and at least one idling spindle. A feed section of the idling spindles is divided into two feeding segments that are driven either in series or in parallel to form a screw spindle pump arrangement with two operating modes. Two tap connections are connected by a connecting line which is provided in a center area of the feed section. The connecting line is blockable, the low-pressure side tap connection is connectable to the high-pressure connection, and the high-pressure side tap connection can be connected to the low-pressure connection. A series circuit is created by the open connecting line, corresponding to a screw spindle pump. With the connecting line blocked, and the simultaneous pressure medium flow paths indicated above, the screw spindle pump arrangement is operable as a parallel circuit.

1 . A screw spindle pump arrangement comprising:
 a low pressure connection;   a high pressure connection;   a drive spindle;   at least one running spindle,   wherein a conveying section of the running spindle is dividable into two conveying sections which are configured to operate either in parallel or in series.   
     
     
         2 . The screw spindle pump arrangement as claimed in  claim 1 , further comprising:
 two tapping connections which can be connected by a connecting line being provided in a central region of the conveying section,   wherein it is possible for the connecting line to be shut off, and   wherein the first tapping connection in the conveying direction is connectable to the high pressure connection and the second tapping connection in the conveying direction is connectable to the low pressure connection.   
     
     
         3 . The screw spindle pump arrangement as claimed in  claim 2 , wherein a spacing of the two tapping connections along the conveying section corresponds at least to a width of one or more helical lands of the running spindles. 
     
     
         4 . The screw spindle pump arrangement as claimed in  claim 2 , wherein:
 a directional valve is arranged in the connecting line,   the directional valve is connected via a high pressure connecting line to the high pressure connection, and   the directional valve is connected via a low pressure connecting line to the low pressure connection.   
     
     
         5 . The screw spindle pump arrangement as claimed in  claim 4 , wherein:
 the connecting line is shut off when a valve body of the directional valve is in a spring prestressed basic position, and   the first tapping connection is connected to the high pressure connection,   the second tapping connection is connected to the low pressure connection, and   the two tapping connections are connected to one another via the connecting line when the valve body is in a switching position.   
     
     
         6 . The screw spindle pump arrangement as claimed in  claim 4 , further comprising:
 a nonreturn valve arranged in the high pressure connecting line,   wherein the nonreturn valve opens from the directional valve to a high pressure line which connects the high pressure connection to a pump outlet.   
     
     
         7 . The screw spindle pump arrangement as claimed in  claim 1 , further comprising:
 a pressure limiting valve connected to the high pressure line, and   wherein the pressure limiting valve is configured to relive the high pressure line to a tank.   
     
     
         8 . The screw spindle pump arrangement as claimed in  claim 7 , wherein the pressure limiting valve is pilot controlled pneumatically. 
     
     
         9 . The screw spindle pump arrangement as claimed in  claim 3  further comprising:
 two running spindles, 
 wherein threads of the two running spindles are wound in the same direction. 
 
     
     
         10 . The screw spindle pump arrangement as claimed in  claim 1 , wherein the drive spindle is driven by a two pole electric motor. 
     
     
         11 . The screw spindle pump arrangement as claimed in  claim 1 , wherein:
 the drive spindle is connected to a speed-controlled electric motor, and   a pressure sensor is connected to the electric motor and is arranged on the high pressure line.   
     
     
         12 . The screw spindle pump arrangement as claimed in  claim 1 , wherein the screw spindle pump arrangement is configured to supply a machine tool with coolant and/or lubricant.