Cold header for cryogenic refrigerating machine

Abstract

A cold head for cryogenic machines comprises a displacer mounted in a working chamber of a housing. The cold head also has a high-pressure connection for supplying highly compressed refrigerant and a low-pressure connection for discharging expanded refrigerant. Also provided is a control valve arrangement for controlling the supply and discharge of refrigerant. According to the invention there is a bypass channel connecting the high-pressure connection to the low-pressure connection.

What is claimed is: 
     
         1 . Cold head for cryogenic refrigeration machines, comprising
 a displacer mounted in a working chamber of a housing,   a high-pressure connection for supplying highly compressed refrigerant into the working chamber,   a low-pressure connection for discharging expanded refrigerant from the working chamber, and   a control valve device for controlling the supply and discharge of refrigerant into and from the working chamber,   wherein   a bypass channel connecting the high-pressure connection to the low-pressure connection.   
     
     
         2 . Cold head for cryogenic refrigeration machines of  claim 1 , wherein a throughflow regulation device is arranged in the bypass channel. 
     
     
         3 . Cold head for cryogenic refrigeration machines of  claim 2 , wherein the throughflow regulation device is adjustable in particular during operation. 
     
     
         4 . Cold head for cryogenic refrigeration machines of  claim 1 , further comprising a movement device for moving the displacer. 
     
     
         5 . Cold head for cryogenic refrigeration machines of  claim 4 , wherein the movement device is configured as a piston-cylinder unit which, for actuation, is connected to the high-pressure connection and the low-pressure connection. 
     
     
         6 . Cold head for cryogenic refrigeration machines of  claim 4 , wherein the movement device has a motor. 
     
     
         7 . Cold head for cryogenic refrigeration machines of  claim 14 , wherein the electric motor drives an eccentric that acts on a slotted guide to cause a linear movement of the displacer. 
     
     
         8 . Cold head for cryogenic refrigeration machines of  claim 1 , wherein the control valve device has a cyclically operating, multi-channel control valve that controls the connection of a working chamber to a high-pressure connection and to a low-pressure connection. 
     
     
         9 . Cold head for cryogenic refrigeration machines of  claim 8 , wherein the control valve controls the connection of the piston-cylinder unit. 
     
     
         10 . Cold head for cryogenic refrigeration machines of  claim 1 , further comprising a distributor body in which at least a first connecting channel is provided for connecting the high-pressure connection to the working chamber. 
     
     
         11 . Cold head for cryogenic refrigeration machines of  claim 10 , wherein the first connecting channel is arranged between the control valve and the working chamber. 
     
     
         12 . Cold head for cryogenic refrigeration machines of  claim 8 , wherein the distributor body has a second connecting channel between the control valve and the low-pressure connection. 
     
     
         13 . Cold head for cryogenic refrigeration machines of  claim 10 , wherein the distributor body has a control channel for supplying and/or discharging a control medium, in particular a refrigerant, to and/or from the piston-cylinder unit. 
     
     
         14 . Cold head for cryogenic refrigeration machines of  claim 6 , wherein the motor is an electric motor.