Piston pump with at least one stepped piston element

Abstract

A piston pump with at least one driven stepped piston element disposed longitudinally movably in a housing is disclosed. The piston element and housing define a plurality of pressure chambers whose volumes vary as a function of the motion of the stepped piston. A volume of the first pressure chamber is decreased during an intake stroke of the piston that increases the volume of the second pressure chamber. A volume of a third pressure chamber, communicating with the pumping side and defined by the stepped piston element and the housing, is increased by a defined volumetric value during the compression stroke and decreased by the during the intake stroke; the defined volumetric value is less than the change in volume of the second pressure chamber during the compression stroke of the stepped piston element.

1 - 12 . (canceled) 
   
   
       13 . In a piston pump having at least one stepped piston element, drivable via a drive mechanism and disposed longitudinally movably in a housing, which element is operatively connected to the drive mechanism in such a way that via the operative connection, both tensile and compressive forces can be transmitted, and having at least two pressure chambers each, which can be made to communicate via an inlet valve device for carrying fluid out of the first pressure chamber, connected to an intake region, into the second pressure chamber and whose volumes vary as a function of a motion of the stepped piston element, and a volume of the first pressure chamber is decreased during an intake stroke of the stepped piston element that increases the volume of the second pressure chamber the volume of the first pressure chamber being decreased during a compression stroke of the stepped piston element that increases the volume of the second pressure chamber, and the second pressure chamber can be made to communicate with a pumping side via an outlet valve device, the improvement wherein a volume of a third pressure chamber, communicating with the pumping side and defined at least by the stepped piston element and the housing, is increased by a defined volumetric value during the compression stroke of the stepped piston element and is decreased by the defined volumetric value during the intake stroke of the stepped piston element, and where the defined volumetric value is less in amount than the change in volume of the second pressure chamber during the compression stroke of the stepped piston element. 
   
   
       14 . The piston pump as defined by  claim 13 , further comprising a stepped guide sleeve between the stepped piston element and the housing, which stepped guide at least partly represents a boundary of the first pressure chamber relative to the intake region. 
   
   
       15 . The piston pump as defined by  claim 14 , further comprising a bore in the guide sleeve providing communication between the first pressure chamber and the intake region. 
   
   
       16 . The piston pump as defined by  claim 14 , wherein the guide sleeve at least partly represents a boundary of the third pressure chamber relative to the pumping side. 
   
   
       17 . The piston pump as defined by  claim 15 , wherein the guide sleeve at least partly represents a boundary of the third pressure chamber relative to the pumping side. 
   
   
       18 . The piston pump as defined by  claim 14 , further comprising at least one slit in the guide sleeve, third pressure chamber communicating with the pumping side via the at least one slit. 
   
   
       19 . The piston pump as defined by  claim 15 , further comprising at least one slit in the guide sleeve, third pressure chamber communicating with the pumping side via the at least one slit. 
   
   
       20 . The piston pump as defined by  claim 16 , further comprising at least one slit in the guide sleeve, third pressure chamber communicating with the pumping side via the at least one slit. 
   
   
       21 . The piston pump as defined by  claim 13 , further comprising an insert element fixed relative to the housing and the stepped piston element and defining the second pressure chamber. 
   
   
       22 . The piston pump as defined by  claim 14 , further comprising an insert element fixed relative to the housing and the stepped piston element and defining the second pressure chamber. 
   
   
       23 . The piston pump as defined by  claim 18 , further comprising an insert element fixed relative to the housing and the stepped piston element and defining the second pressure chamber. 
   
   
       24 . The piston pump as defined by  claim 23 , wherein the third pressure chamber is defined by the stepped piston element, the guide sleeve, and the insert element. 
   
   
       25 . The piston pump as defined by  claim 14 , wherein the guide sleeve is fixed via a partial press fit in the housing that seals off the intake region from the pumping side. 
   
   
       26 . The piston pump as defined by  claim 21 , further comprising a fourth pressure chamber is defined by the stepped piston element and the insert element, and an overflow cuff sealing off the fourth pressure chamber from the third pressure chamber, and wherein the volume of the fourth chamber varies as a function of the motion of the stepped piston element. 
   
   
       27 . The piston pump as defined by  claim 24 , further comprising a fourth pressure chamber is defined by the stepped piston element and the insert element, and an overflow cuff sealing off the fourth pressure chamber from the third pressure chamber, and wherein the volume of the fourth chamber varies as a function of the motion of the stepped piston element. 
   
   
       28 . The piston pump as defined by  claim 26 , wherein the overflow cuff is embodied with a sealing function such that a positive pressure drop between the fourth pressure chamber and the third pressure chamber can be rescinded via the overflow cuff in the direction of the third pressure chamber. 
   
   
       29 . The piston pump as defined by  claim 13 , wherein the defined volumetric value by which the volume of the third pressure chamber varies as a function of the motion of the stepped piston element corresponds at least approximately to half the amount of the change in volume of the second pressure chamber. 
   
   
       30 . The piston pump as defined by  claim 14 , wherein the defined volumetric value by which the volume of the third pressure chamber varies as a function of the motion of the stepped piston element corresponds at least approximately to half the amount of the change in volume of the second pressure chamber. 
   
   
       31 . The piston pump as defined by  claim 13 , wherein the area ratios of the operative end faces of the stepped piston element are provided such that the volume of the first pressure chamber that is established as a function of the motion of the stepped piston element varies at least approximately by half the amount of the change in volume of the second pressure chamber. 
   
   
       32 . The piston pump as defined by  claim 14 , wherein the area ratios of the operative end faces of the stepped piston element are provided such that the volume of the first pressure chamber that is established as a function of the motion of the stepped piston element varies at least approximately by half the amount of the change in volume of the second pressure chamber.