Membrane Pump Having an Inertially Controlled Leakage Compensation Valve

Abstract

The present invention concerns a membrane pump having a hydraulic chamber ( 8 ) separated from a pumping chamber ( 9 ) by a membrane ( 1 ), wherein the pumping chamber ( 9 ) is respectively connected with a suction connection and a pressure connection and a pulsating working fluid pressure can be applied to the hydraulic chamber ( 8 ) which can be filled with a working fluid, wherein the hydraulic chamber ( 8 ) is connected to a working fluid reservoir ( 15 ) via a leakage compensation valve ( 6 ), wherein the leakage compensation valve ( 6 ) comprises a closing body which is held in a closed position with the aid of a pressure element and which can be moved to and fro between closed and opened valve gate positions, wherein the pressure element is designed such that when the pressure in the hydraulic chamber ( 8 ) is lower than a set pressure p L , the closing body ( 16 ) moves in the direction of the open position. In order to provide a membrane pump with an improved a leakage compensation valve, the invention proposes that the mass of the closing body is large enough for the closing body to move by no more than 0.2 mm in the direction of the open position when a drop in pressure to 0 bar which lasts no longer than 1 millisecond occurs as a result of a pressure pulse in the hydraulic chamber ( 8 ).

1 . A membrane pump having a hydraulic chamber ( 8 ) separated from a pumping chamber ( 9 ) by a membrane ( 1 ), wherein the pumping chamber ( 9 ) is respectively connected with a suction connection and a pressure connection and a pulsating working fluid pressure can be applied to the hydraulic chamber ( 8 ) which can be filled with a working fluid, wherein the hydraulic chamber ( 8 ) is connected to a working fluid reservoir ( 15 ) via a leakage compensation valve ( 6 ), wherein the leakage compensation valve ( 6 ) comprises a closing body which is held in a closed position with the aid of a pressure element and which can be moved to and fro between the closed position in which the valve gate is closed and an open position in which the valve gate is open, wherein the pressure element is designed such that when the pressure in the hydraulic chamber ( 8 ) is lower than a set pressure p L , the closing body ( 16 ) moves in the direction of the open position, characterized in that the mass of the closing body ( 16 ) is large enough for the closing body ( 16 ) to move by no more than 0.2 mm in the direction of the open position when a drop in pressure to 0 bar which lasts no longer than 1 millisecond occurs as a result of a pressure pulse in the hydraulic chamber ( 8 ). 
     
     
         2 . A membrane pump according to  claim 1 , characterized in that the mass of the closing body ( 16 ) is selected such that the closing body ( 16 ) moves by no more than 0.1 mm in the direction of the open position when a drop in pressure which lasts no longer than 1 millisecond occurs as a result of a pressure pulse in the hydraulic chamber ( 8 ). 
     
     
         3 . A membrane pump according to any one of  claims 1  and  2 , characterized in that the closing body ( 16 ) moves by no more than 0.2 mm, preferably by no more than 0.1 mm, in the direction of the open position when a drop in pressure to a minimum pressure p min  which lasts no longer than 1 millisecond occurs as a result of a pressure pulse in the hydraulic chamber ( 8 ), wherein p min  is the minimum pressure in the hydraulic chamber arising on the occurrence of a pressure pulse as a result of a change in the velocity of the fluid through the suction connection during the suction stroke. 
     
     
         4 . A membrane pump according to one of  claims 1  to  2 , characterized in that p L  is higher than the minimum pressure in the hydraulic chamber ( 8 ). 
     
     
         5 . A method for dimensioning a leakage compensation valve ( 6 ) of a membrane pump having a hydraulic chamber ( 8 ) separated from a pumping chamber ( 9 ) by a membrane ( 1 ), wherein the pumping chamber ( 9 ) is respectively connected with a suction connection and a pressure connection, and a pulsating working fluid pressure can be applied to the hydraulic chamber ( 8 ) which can be filled with a working fluid, wherein the hydraulic chamber ( 8 ) is connected to a working fluid reservoir ( 15 ) via a leakage compensation valve ( 6 ), wherein the leakage compensation valve ( 6 ) comprises a closing body ( 16 ) which can be moved to and fro between a closed position in which the valve gate is closed and an open position in which the valve gate is open, characterized in that the mass of the closing body ( 16 ) is selected such that the closing body ( 16 ) moves by no more than 0.2 mm, preferably by no more than 0.1 mm, in the direction of the open position when a drop in pressure which lasts no longer than 1 millisecond occurs as a result of a pressure pulse in the hydraulic chamber ( 8 ). 
     
     
         6 . A membrane pump according to  claim 1 , characterized in that the closing body ( 16 ) moves by no more than 0.2 mm, preferably by no more than 0.1 mm, in the direction of the open position when a drop in pressure to a minimum pressure p min  which lasts no longer than 1 millisecond occurs as a result of a pressure pulse in the hydraulic chamber ( 8 ), wherein p min  is the minimum pressure in the hydraulic chamber arising on the occurrence of a pressure pulse as a result of a change in the velocity of the fluid through the suction connection during the suction stroke, and characterized in that p L  is higher than the minimum pressure in the hydraulic chamber ( 8 ).