Magnetic Refrigeration System with Improved Coaxial Valve

Abstract

A magnetic refrigeration system provides a rotary valve design that balances the forces needed to seal valve surfaces, reduces influence of wear on leakage, makes assembly and adjustment of the valve easier, reduces potential for bypass flows, reduces stress on and corrosion of the drive shaft, and provides a more compact system.

We claim: 
     
         1 . An active magnetic regenerative refrigerator (AMR) apparatus, comprising:
 a first AMR bed with a first end and a second end;   a first heat exchanger (HEX) with an inlet and an outlet;   a shaft rotatable along an axis;   a magnet attached to the shaft to apply a time-varying magnetic field to the first AMR bed with rotation of the shaft;   a first valve switchably connecting the outlet of the first HEX to the first end of the AMR bed for fluid flow therebetween when the field on the first AMR bed is in a low state relatively removed from the magnet;   a second valve switchably connecting the inlet of the first HEX to the first end of the AMR bed for fluid flow therebetween when the field on the first AMR bed is in a high state relatively proximate to the magnet; and   wherein the first and second valves include:   (a) at least one pair of valve plates in rotational sliding communication and positioned coaxially about the shaft, wherein a first valve plate is attached to rotate with the shaft with respect to the second valve plate, the valve plates including valve ports that move into alignment and out of alignment to allow fluid flow through the valve ports when in alignment and to block fluid flow through the valve ports when out of alignment, wherein at least one of the valve plates is mounted for movement along the axis of the shaft with respect to another of the valve plates; and   (b) a spring-like object urging the valve plates axially into contact with each other.   
     
     
         2 . The AMR apparatus of  claim 1  wherein the spring-like object is a compression spring positioned between a spring support and a contacted valve plate of the valve plates and wherein the position of the spring support is adjustable to control a force of the spring on the contacted valve plate. 
     
     
         3 . The AMR apparatus of  claim 2  wherein the valve plates are held within a plenum receiving a fluid controlled by the valve and where in the spring support is adjustable by rotation on a threaded element coaxial about the shaft and wherein the plenum includes a sealable opening allowing access to the spring support for rotation of the spring support with respect to the threaded element to move the spring support axially along the shaft. 
     
     
         4 . The AMR apparatus of  claim 2  wherein the first valve plate attaches to the shaft through a joint allowing angulation of the first valve plate in addition to axial movement of the first valve plate while preventing relative motion of the valve plate and shaft in rotation about an axis of the shaft. 
     
     
         5 . The AMR apparatus of  claim 4  wherein the joint provides an interengaging axial slot and radial pin. 
     
     
         6 . The AMR apparatus of  claim 1  wherein the shaft communicates with the first valve plate by means of a key joining a key way and key seat on the shaft and valve plate wherein the key extends to an end of the shaft to allow extraction of the key in a first direction from a first end of the shaft and extraction of the shaft in a second direction opposite the first direction. 
     
     
         7 . The AMR apparatus of  claim 1  wherein the shaft passes through a plenum receiving fluid from a valve and is separated from the plenum by a sleeve assembly. 
     
     
         8 . The AMR apparatus of  claim 7  wherein the sleeve assembly includes a first and second sleeve portion over different axial portions of the shaft each portion including a sliding seal communicating with a corresponding sliding seal of the other portion allowing relative rotational movement of the first sleeve portion with respect to the second sleeve portion about the axis. 
     
     
         9 . The AMR apparatus of  claim 8  wherein the sliding seal includes a spring biasing the first and second seal portion into engagement to prevent leakage therebetween. 
     
     
         10 . The AMR apparatus of  claim 1  wherein the first and second valves comprise one pair of valve plates in rotational sliding communication and positioned coaxially on the rotatable shaft. 
     
     
         11 . The AMR apparatus of  claim 10  wherein the valve plates cooperate to in a first position present a passage of fluid to a first plenum communicating with an outer periphery of at least one valve plate and in a second position to present a fluid passage to a fluid and a second plenum separated from the first plenum communicating with an inner periphery of at least one valve plate. 
     
     
         12 . The AMR apparatus of  claim 1  further including a second heat exchanger (HEX) with an inlet and outlet:
 including a third valve that fluidly connects the inlet of the second HEX to the second end of the AMR bed when the field on the first AMR bed is in a low state; 
 a fourth valve that fluidly connects the outlet of the second HEX to the second end of the AMR bed when the field on the first AMR bed is in a high state. 
 
     
     
         13 . The AMR apparatus of  claim 12  wherein the third and fourth valves are check valves. 
     
     
         14 . The AMR apparatus of  claim 1  wherein at least one valve plate is a carbon material.