Membrane vacuum pump

Abstract

A membrane vacuum pump includes at least one membrane pump stage, at least one inlet valve for a process gas to be conveyed associated with the membrane pump stage, and at least one gas ballast valve for the supply of a ballast gas. The flow path for the ballast gas, leading through the gas ballast valve, opens into the flow path for the process gas behind the inlet valve in the direction of flow of the process gas.

What is claimed is: 
     
         1 . A membrane vacuum pump comprising at least one membrane pump stage ( 12 ), at least one inlet valve ( 20 ) for a process gas to be conveyed and at least one gas ballast valve ( 22 ) for the supply of a ballast gas, wherein the at least one inlet valve ( 20 ) is associated with the membrane pump stage ( 12 ), and wherein the flow path for the ballast gas leading through the gas ballast valve ( 22 ) opens into the flow path for the process gas behind the inlet valve ( 20 ) in the direction of flow of the process gas. 
     
     
         2 . The vacuum pump in accordance with  claim 1 , wherein the flow path for the ballast gas opens into the flow path for the process gas directly behind the inlet valve ( 20 ). 
     
     
         3 . The vacuum pump in accordance with  claim 1 , wherein the gas ballast valve ( 22 ) is an electromagnetic valve. 
     
     
         4 . The vacuum pump in accordance with  claim 1 , further comprising a control device, the control device being operationally connected to the gas ballast valve ( 22 ) and the gas ballast valve ( 22 ) being able to be controlled for actuation by the control device. 
     
     
         5 . The vacuum pump in accordance with  claim 1 , further comprising at least one further membrane pump stage ( 14 ) in addition to the one membrane stage ( 12 ). 
     
     
         6 . The vacuum pump in accordance with  claim 5 , wherein the at least one further membrane pump stage ( 14 ) is connected downstream of the one membrane pump stage ( 12 ) in the direction of flow of the process gas. 
     
     
         7 . The vacuum pump in accordance with  claim 1 , wherein the gas ballast valve ( 22 ) has an adjustable connectivity. 
     
     
         8 . The vacuum pump in accordance with  claim 1 , wherein the gas ballast valve ( 22 ) is a 3/2 way valve. 
     
     
         9 . The vacuum pump in accordance with  claim 1 , further comprising a filter for filtering the ballast gas. 
     
     
         10 . The vacuum pump in accordance with  claim 9 , wherein the filter is arranged in front of the opening of the flow path of the ballast gas into the flow path of the process gas in the direction of flow of the ballast gas. 
     
     
         11 . The vacuum pump in accordance with  claim 1 , wherein a drive unit of the vacuum pump and the gas ballast valve ( 22 ) can be actuated with an electrical voltage of the same value. 
     
     
         12 . The vacuum pump in accordance with  claim 1 , further comprising a common power supply unit for the provision of a power supply for the drive unit and for the gas ballast valve ( 22 ). 
     
     
         13 . A pump arrangement having at least one membrane vacuum pump comprising at least one membrane pump stage ( 12 ), at least one inlet valve ( 20 ) for a process gas to be conveyed and at least one gas ballast valve ( 22 ) for the supply of a ballast gas, wherein the at least one inlet valve ( 20 ) is associated with the membrane pump stage ( 12 ), and wherein the flow path for the ballast gas leading through the gas ballast valve ( 22 ) opens into the flow path for the process gas behind the inlet valve ( 20 ) in the direction of flow of the process gas; and having a further vacuum pump connected in a gas-conductive manner in series to the membrane vacuum pump upstream of the membrane vacuum pump. 
     
     
         14 . The pump arrangement in accordance with  claim 13 , wherein the further vacuum pump is selected from the group of members comprising a turbomolecular pump, a single-stage or multi-stage Roots pump, a rotary vane pump, a scroll pump, a claw pump, a screw pump, a rotary piston pump and an ion getter pump.