Device for the drive control of a two-cylinder thick matter pump

Abstract

A device for the drive control of a two-cylinder thick matter pump has a diverter which is arranged in a material charging container and a motor-driven hydraulic variable displacement pump, via which both the drive cylinders of the thick matter pump and the drive mechanism of the diverter are controlled. An adjusting throttle is arranged in a pressure line between the high-pressure outlet of the variable displacement pump and the drive cylinders of the thick matter pump. A control line which leads to an adjusting mechanism of the variable displacement pump is coupled back from the pressure line downstream of the adjusting throttle. A connecting line which leads to a supply connector of the diverter hydraulics and in which a fixedly adjusted throttle can be arranged is branched off from the pressure line upstream of the adjusting throttle.

1 . A device for the drive control of a two-cylinder thick matter pump,
 with two conveying cylinders ( 14 ,  14 ′) which issue via end-face orifices into a material feed container ( 10 ) and the conveying pistons ( 16 ,  16 ′) of which can be actuated by means of hydraulically activated drive cylinders ( 18 ,  18 ′) alternately in reciprocal motion so as to execute a filling stroke ( 19 ′) and a conveying stroke ( 19 ″),   with a pipe switch ( 22 ) which is arranged inside the material feed container ( 10 ), can be connected by means of a hydraulic drive mechanism ( 24 ) alternately on the inlet side to the orifice ( 12 ) of one of the conveying cylinders ( 14 ,  14 ′) and releases the orifice ( 12 ′) of the other conveying cylinder ( 14 ,  14 ′) in each case and which is connected on the outlet side to a conveying line ( 26 ),   with a motor-driven hydraulic variable displacement pump ( 28 ) which has a suction inlet ( 32 ) connected to a pressureless reservoir ( 30 ) and a high-pressure outlet ( 36 ),   the drive cylinders ( 18 ,  18 ′) being connectable alternately, in each case via a hydraulic connection ( 38 ,  38 ′) located at one of their ends, by means of a first reversing valve ( 40 ) to the high-pressure outlet ( 36 ) of the variable displacement pump ( 28 ) via a delivery line ( 34 ) and to the reservoir ( 30 ) via a return line ( 50 ),   the drive cylinders ( 18 ,  18 ′) being connected to one another at their other end via a rocking oil line ( 44 ),   the hydraulic drive mechanism ( 24 ) of the pipe switch ( 22 ) having a cylinder arrangement which is activated on two sides and the connections of which can be connected alternately via a second reversing valve ( 48 ) to the delivery line ( 34 ) leading to the high-pressure outlet ( 36 ) of the hydraulic variable displacement pump ( 28 ) and to the return line ( 50 ) leading to the reservoir ( 30 ),   and with a central control ( 56 ), responding to end-of-travel signals of the passing drive pistons ( 20 ,  20 ′) of at least one of the drive cylinders ( 18 ,  18 ′), for triggering a follow-up control for the first and second reversing valve ( 48 ),   wherein a setting throttle ( 58 ) is arranged in the delivery line ( 34 ) between the high-pressure outlet ( 36 ) of the variable displacement pump ( 28 ) and the first reversing valve ( 40 ),   wherein a control line ( 62 ) leading directly to an adjusting mechanism ( 60 ) of the variable displacement pump ( 28 ) is fed back from the delivery line ( 34 ) downstream ( 58 ′) of the setting throttle ( 58 ),   and wherein a connecting line ( 66 ) leading to a supply connection ( 64 ) of the second reversing valve ( 48 ) is branched off from the delivery line ( 34 ) upstream ( 58 ″) of the setting throttle ( 58 ).   
     
     
         2 . The device as claimed in  claim 1 , wherein a permanently set throttle ( 68 ) is arranged in the connecting line ( 66 ). 
     
     
         3 . The device as claimed in  claim 1 , wherein the cylinder arrangement activated on two sides comprises two series-connected plunger cylinders, the connections of which are connected to the second reversing valve. 
     
     
         4 . The device as claimed in  claim 1 , wherein the variable displacement pump ( 28 ) comprises a pressure regulator for spilling the conveying quantity when a stipulated maximum pressure is exceeded. 
     
     
         5 . The device as claimed in  claim 1 , wherein the adjusting mechanism ( 60 ) comprises load-sensing hydraulics ( 70 ) activated via the pressure drop at the setting throttle ( 58 ) as a control variable. 
     
     
         6 . The device as claimed in  claim 5 , wherein the load-sensing hydraulics ( 70 ) has a mechanically adjustable swashplate ( 72 ) arranged in the variable displacement pump ( 28 ), as an adjusting member, and also a pressure balance ( 73 ) which is connected to the swashplate ( 72 ) and is spring-supported on the force side and to which the control line ( 62 ) branched off downstream ( 58 ′) of the setting throttle ( 58 ) is connected on the load side. 
     
     
         7 . The device as claimed in  claim 1 , wherein the drive cylinders ( 18 ,  18 ′) have at least two cylinder switching sensors ( 52 ,  54 ) which respond to the passing drive pistons ( 20 ,  20 ′) and which are connected on the output side to signal inputs of the central control ( 56 ). 
     
     
         8 . The device as claimed in  claim 1 , wherein the drive mechanism ( 24 ) of the pipe switch ( 22 ) has at least one pipe switch sensor ( 74 ) which responds to the position, the speed or the ends of travel of the pipe switch ( 22 ) and which is connected on the output side to a further signal input of the central control ( 56 ). 
     
     
         9 . The device as claimed in  claim 1 , wherein the reversing valves ( 40 ,  48 ) are designed as directional valves with electromagnetic pilot control members ( 76 ,  78 ), the pilot control members ( 76 ,  78 ) of which are connected in each case to a control output ( 76 ′,  78 ′) of the central control ( 56 ).