Cryogenic Cooling Pump and Method

Abstract

A pump ( 10 ) for circulating a cryogenic coolant, comprising: a cylinder housing ( 14 ); a piston ( 16 ) received in said cylinder housing ( 14 ) for reciprocating in said cylinder housing ( 14 ) between a first death center position ( 18 ) and a second death center position ( 20 ), said first death center position ( 18 ) and said second death center position ( 20 ) defining a compression chamber ( 22 ) therebetween; an outlet ( 34 ) for said compression chamber ( 22 ); and an inlet ( 36 ) formed in a wall ( 24 ) of said cylinder housing ( 14 ) at a position between said first death center position ( 18 ) and said second death center position ( 20 ); wherein said inlet ( 36 ) is adapted to establish a fluid connection between said compression chamber ( 22 ) and a coolant reservoir ( 40; 76 ).

1 . A pump for circulating a cryogenic coolant, comprising:
 a cylinder housing;   a piston received in said cylinder housing for reciprocating in said cylinder housing between a first death center position and a second death center position, said first death center position and said second death center position defining a compression chamber therebetween;   an outlet for said compression chamber; and   an inlet formed in a wall of said cylinder housing at a position between said first death center position and said second death center position;   wherein said inlet is adapted to establish a fluid connection between said compression chamber and a coolant reservoir.   
     
     
         2 . The pump according to  claim 1 , wherein said inlet is covered by said piston, when said piston is at said first death center position, and is opened when said piston moves from said first death center position towards said second death center position. 
     
     
         3 . The pump according to  claim 1 , comprising a fluid conduit in fluid communication with said inlet, said fluid conduit for establishing said fluid connection between said compression chamber and said coolant reservoir. 
     
     
         4 . The pump according to  claim 1 , comprising a driving unit for reciprocating said piston in said cylinder housing, wherein said driving unit is adapted to drive said piston from said first death center position towards said second death center position at a first velocity, and to drive said piston from said second death center position towards said first death center position at a second velocity, said second velocity preferably lower than said first velocity. 
     
     
         5 . The pump according to  claim 1 , wherein one or both of said outlet and said inlet is or are provided with valves. 
     
     
         6 . The pump according to  claim 1 , comprising a driving unit for reciprocating said piston in said cylinder housing, wherein said driving unit comprises a magnetic core integrated into said piston or mounted to said piston, and further comprises a magnetic actuator located externally to said cylinder housing, said magnetic actuator adapted to generate a magnetic field for driving said piston by acting upon said magnetic core. 
     
     
         7 . The pump according to  claim 1 , comprising a sealing element for sealing said piston against an inner sidewall of said cylinder housing. 
     
     
         8 . The pump according to  claim 1 , comprising mounting means for mounting said pump to a cryocooler, wherein said coolant reservoir comprises a condensate storage vessel of said cryocooler and wherein said inlet is adapted to establish a fluid connection to said condensate storage vessel via a fluid conduit. 
     
     
         9 . A system for circulating a cryogenic coolant, comprising a cryocooler and a pump, said pump comprising a cylinder housing;
 a piston received in said cylinder housing for reciprocating in said cylinder housing between a first death center position and a second death center position, said first death center position and said second death center position defining a compression chamber therebetween;   an outlet for said compression chamber; and   an inlet formed in a wall of said cylinder housing at a position between said first death center position and said second death center position;   wherein said inlet is adapted to establish a fluid connection between said compression chamber and a coolant reservoir,   wherein said coolant reservoir comprises a condensate storage vessel of said cryocooler and wherein said pump is mounted to said cryocooler, and wherein said system comprises a fluid conduit for establishing a fluid connection between said inlet and said condensate storage vessel.   
     
     
         10 . The system according to  claim 9 , wherein one or both of said cylinder housing and said compression chamber is or are thermally coupled to a cold head of said cryocooler at a lower end of said cylinder housing. 
     
     
         11 . The system according to  claim 10 , further comprising an additional pump coupled to a first stage of said cryocooler. 
     
     
         12 . A system for circulating a cryogenic coolant, comprising a coolant storage vessel and a pump,
 said pump comprising,   a cylinder housing,   a piston received in said cylinder housing for reciprocating in said cylinder housing between a first death center position and a second death center position, said first death center position and said second death center position defining a compression chamber therebetween,   an outlet for said compression chamber, and   an inlet formed in a wall of said cylinder housing at a position between said first death center position and said second death center position,   wherein said inlet is adapted to establish a fluid connection between said compression chamber and a coolant reservoir,   wherein said coolant storage vessel comprises said coolant reservoir and wherein said pump is mounted to said coolant storage vessel, and wherein said system comprises a fluid conduit for establishing the fluid connection between said inlet and said coolant reservoir.   
     
     
         13 . A method for circulating a coolant by means of a pump, said pump comprising a cylinder housing and a piston received in said cylinder housing for reciprocating in said cylinder housing between a first death center position and a second death center position, said first death center position and said second death center position defining a compression chamber therebetween, wherein said method comprising:
 moving said piston from said first death center position to said second death center position, thereby exposing an inlet formed in a wall of said cylinder housing and sucking said coolant from a coolant reservoir through said inlet into said compression chamber;   moving said piston from said second death center position towards said first death center position past said inlet, thereby compressing said coolant in said compression chamber; and   expelling said compressed coolant from said compression chamber through an outlet.   
     
     
         14 . The method according to  claim 13 , wherein said moving said piston from said second death center position to said first death center position comprises covering said inlet and/or sealing said inlet. 
     
     
         15 . The method according to  claim 13 , wherein said piston is moved from said first death center position to said second death center position at a first velocity, and wherein said piston is moved from said second death center position to said first death center position at a second velocity, wherein said second velocity is higher than said first velocity. 
     
     
         16 . The method according to  claim 13 , comprising providing said coolant expelled through said outlet to an object to be cooled. 
     
     
         17 . The pump according to  claim 2 , wherein said inlet is sealed by said piston, when said piston is at said first death center position, and is opened when said piston moves from said first death center position towards said second death center position. 
     
     
         18 . The system of  claim 10 , wherein said pump is detachably mounted to said cryocooler. 
     
     
         19 . The system of  claim 14 , wherein said pump is detachably mounted to said coolant storage vessel. 
     
     
         20 . The method of  claim 17 , wherein said covering and/or sealing comprises covering and/or sealing said inlet by means of said piston. 
     
     
         21 . The method of  claim 20 , further comprising providing said coolant from said object to be cooled to said coolant reservoir.