Expansion valve

Claim 1

An expansion valve for a compression type refrigerating unit having an evaporator, a compressor, and a condenser; said valve comprising an open ended tubular body having coaxial longitudinal bores of different diameters defining a shoulder therebetween with the smaller bore terminating in a valve seat at said shoulder, and having longitudinally spaced apart lateral openings which provide inlet and outlet ports intersecting the respective smaller and larger bores upstream and downstream of said valve seat for flow of refrigerant from the condenser to the evaporator; a valve member movable in said larger bore into and out of engagement with said valve seat to regulate the flow of refrigerant from said inlet port to said outlet port; said valve member having a stem portion of diameter substantially equal to the diameter of said valve seat and said smaller bore, and a packing ring between said stem portion and said smaller bore effective to slidably seal sAid stem portion in said smaller bore axially beyond said inlet port; said stem portion between said valve member and said inlet port being of diameter smaller than said smaller bore thereby to provide an annular passage for flow of refrigerant from said inlet port to said outlet port when said valve member is moved out of engagement with said valve seat; said smaller bore terminating at one end of said body in an enlarged internally threaded bore, and said larger bore having an internally threaded portion adjacent to said outlet port and an unthreaded counterbored portion open at the other end of said body; a temperature responsive power unit screwed into said enlarged threaded bore and having a movable power element engaged with said stem portion and exposed to refrigerant pressure downstream of said valve seat via a passage in said body opening into a shoulder defined between said smaller bore and said enlarged internally threaded bore thus to move said valve member to control the flow of refrigerant from said inlet port to said outlet port via said seat; an adjusting screw having threaded engagement with said threaded portion, and a packing ring between said adjusting screw and said unthreaded counterbored portion to provide sliding sealed engagement of said adjusting screw with said unthreaded counterbored portion in various positions of adjustment of said adjusting screw and during adjustment thereof; and spring means adjustably compressed between said adjusting screw and said valve member tending to urge said valve member into engagement with said valve seat.