Rotary displacement pump

Abstract

A rotary displacement pump ( 2 ) for pumping a medium, having a pump housing ( 3 ); a reception chamber ( 4 ) which is formed in the pump housing ( 3 ), with an inlet area ( 26 ) and an outlet area ( 27 ); at least one rotary displacement element ( 5, 6 ) which is accommodated in the reception chamber ( 4 ), and which is rotatably attached by means of at least one bearing ( 40, 41, 56 ) in the pump housing ( 3 ), and which presents at least one delimitation surface ( 21 ), by means of which it delimits at least one work space ( 19 ) of the pump ( 2 ); and a bypass ( 59 ) which allows the return flow of a part of the pumped medium from the outlet area ( 27 ) into the inlet area ( 26 ). The rotary displacement element ( 5, 6 ) and/or a rotating part ( 35 ) which is connected to the rotary displacement element can present at least one counter surface ( 64 ) which delimits the bypass ( 59 ), and whose counter surface normal ( 65 ) has at least one component which is directed opposite to the delimitation surface normal ( 66 ) of the delimitation surface ( 21 ).

1 . Rotary displacement pump ( 2 ) for pumping a medium, with
 a pump housing ( 3 ),   a reception chamber ( 4 ) which is formed in the pump housing ( 3 ), with an inlet area ( 26 ) and an outlet area ( 27 ), and   at least one rotary displacement element ( 5 ,  6 ) which is accommodated in the reception chamber ( 4 ), and which is rotatably attached by means of at least one bearing ( 40 ,  41 ,  56 ) in the pump housing ( 3 ), and which presents at least one delimitation surface ( 21 ), by means of which it delimits at least one work space ( 19 ) of the pump ( 2 ), and   a bypass ( 59 ) which allows the return flow of a part of the pumped medium from the outlet area ( 27 ) into the inlet area ( 26 ),   where the rotary displacement element ( 5 ,  6 ) and/or a rotating part ( 35 ) which is connected to the rotary displacement element present(s) at least one counter surface ( 64 ) which delimits the bypass ( 59 ), and whose counter surface normal ( 65 ) has at least one component which is directed opposite to the delimitation surface normal ( 66 ) of the delimitation surface ( 21 ).   
   
   
       2 . Rotary displacement pump according to  claim 1 , wherein the delimitation surface ( 21 ) is an axial delimitation surface ( 20 ) which delimits the work space ( 19 ) axially. 
   
   
       3 . Rotary displacement pump according to  claim 1 , wherein the counter surface ( 64 ) is arranged so it faces the delimitation surface ( 21 ). 
   
   
       4 . Rotary displacement pump according to  claim 1 , wherein the bypass ( 59 ) presents a valve ( 67 ) for the control and/or regulation of the flow of the return-flow medium through the bypass ( 59 ). 
   
   
       5 . Rotary displacement pump according to  claim 1 , wherein one of the rotary displacement elements ( 5 ) is designed as a housing element ( 8 ) which encloses eccentrically a rotary displacement element ( 6 ) designed as an inner rotary displacement element ( 15 ). 
   
   
       6 . Rotary displacement pump according to  claim 5 , wherein the housing element ( 5 ) is designed as a hypotrochoid housing ( 10 ) with n chambers, and the inner rotary displacement element ( 15 ) presents n-1 corresponding teeth ( 17 ) for engagement in the chambers. 
   
   
       7 . Rotary displacement pump according to  claim 1 , wherein the rotating part ( 35 ) is a shaft ( 34 ) or presents a shaft ( 34 ). 
   
   
       8 . Rotary displacement pump according to  claim 7 , wherein the shaft ( 34 ) contributes to the formation of the bypass ( 59 ). 
   
   
       9 . Rotary displacement pump according to  claim 1 , wherein the rotary displacement element ( 5 ) is a rotary displacement element ( 5 ) which can be driven by an associated driving motor. 
   
   
       10 . Rotary displacement pump according to  claim 9 , wherein a coupling ( 37 ), particularly a magnetic coupling ( 36 ), which is arranged between the shaft ( 34 ) and the driving motor. 
   
   
       11 . Rotary displacement pump according to  claim 10 , wherein the coupling ( 37 ) contributes to the formation of the bypass ( 59 ). 
   
   
       12 . Rotary displacement pump according to  claim 4 , wherein the valve ( 67 ) presents a valve-internal mechanism for the valve-internal control of the flow through the bypass ( 59 ) as a function of the pressure exerted at the inlet side of the valve ( 67 ). 
   
   
       13 . Rotary displacement pump according to  claim 1 , wherein the pump ( 2 ) is designed as a rotary displacement pump ( 68 ) without moving seal. 
   
   
       14 . Rotary displacement pump according to  claim 1 , wherein the pump housing ( 3 ) and/or the shaft ( 34 ) consist(s) of stainless steel and/or a Hastelloy nickel based alloy and/or titanium. 
   
   
       15 . Rotary displacement pump according to  claim 1 , wherein the bearings ( 40 ,  41 ,  56 ) and/or the rotary displacement elements ( 5 ,  6 ) consist(s)—at least in part—of the materials Teflon and/or carbon and/or Peek and/or non galling alloys.