| 摘要 |
This expansion valve (10) can be used for a refrigeration system (1) having a compressor (2), an evaporator (3) and a condenser (4). The valve (10) comprises a body (12) including an inlet passage (26), an outlet passage (38), a piston passage (28) defining a piston port (30) and valve chamber (32), the piston passage (28) defining a piston chamber (46) communicating with valve chamber (32). A piston (40) is movably mounted in the piston passage (28) and selectively controls flow through the piston port (30), the piston (40) having an interior passage (60) communicating with the inlet passage (26) and having a pin port (62) communicating with the valve chamber (32), the piston (40) having a biasing spring (52) biasing the piston (40) into a closed position. A valve pin (70) is movably mounted in the valve chamber (32) and controls flow through the valve pin port (62), the valve pin (70) having a spring (74) biasing the pin (70) into the closed position. A temperature responsive diaphragm assembly (18) including a bulb (84) responsive to the outlet temperature of the evaporator (3) includes a diaphragm (82) connected to the valve pin (70) by pushrods (90) tending to move the pin (70) into an open position during normal load conditions and selectively connected to piston (40) tending to move the piston (40) into an open position during overload conditions to increase refrigerant flow through the valve (10). In a modified form of the valve (10a), the piston (40a) is provided with a bleed control member (100) which permits bleed during normal operation but precludes bleed when the valve (10a) is closed. <IMAGE> |
