초록 ▼

A refrigerant system includes a compressor with a discharge valve that temporarily restricts the compressor's outflow at startup so that the discharge pressure can quickly rise to force lubricant back to the compressor. The discharge valve also helps prevent an axial face of a rotor of a screw compr

A refrigerant system includes a compressor with a discharge valve that temporarily restricts the compressor's outflow at startup so that the discharge pressure can quickly rise to force lubricant back to the compressor. The discharge valve also helps prevent an axial face of a rotor of a screw compressor from rubbing against a bearing housing axial face of the compressor's housing. When the system turns off under certain low ambient air temperature conditions, the valve closes to help prevent the system's evaporator from freezing up. The discharge valve includes a novel arrangement of a piston, a valve stem extending from the piston, and a valve plug pivotally attached to the valve stem. The pivotal connection ensures a positive seal between the valve plug and a valve seat. A somewhat restricted fluid passageway between the valve's discharge chamber and piston chamber helps prevent the valve from chattering as the valve opens.

대표청구항 ▼

1. A refrigerant system circulating a refrigerant to create a high-pressure side and a low-pressure side, the refrigerant system comprising: a compressor defining a discharge port at the high-pressure side, defining a suction port at the low-pressure side, and defining an oil inlet, the compressor b

1. A refrigerant system circulating a refrigerant to create a high-pressure side and a low-pressure side, the refrigerant system comprising: a compressor defining a discharge port at the high-pressure side, defining a suction port at the low-pressure side, and defining an oil inlet, the compressor being operable to compress the refrigerant to create a pressure differential between the high-pressure side and the low-pressure side;an oil separator defining a refrigerant inlet, a refrigerant outlet, and an oil outlet, wherein the refrigerant inlet is in fluid communication with the discharge port of the compressor;an oil return conduit connecting the oil outlet of the oil separator in fluid communication with the oil inlet of the compressor;an evaporator defining an evaporator inlet and an evaporator outlet, wherein the evaporator outlet is connected in fluid communication with the suction port of the compressor;a condenser defining a condenser inlet and a condenser outlet;an expansion device connecting the condenser outlet in fluid communication with the evaporator inlet; anda discharge valve defining a discharge chamber, a piston chamber, a valve inlet connected in fluid communication with the refrigerant outlet of the oil separator, a valve outlet connected in fluid communication with the condenser inlet, and a valve actuator port connected in fluid communication with the condenser inlet, the discharge valve comprises:a) a piston disposed within the piston chamber so as to substantially isolate the valve actuator port from the discharge chamber;b) a valve seat;c) a valve plug disposed within the discharge chamber and being movable relative to the valve seat between a closed position and an open position, wherein valve plug in the closed position sealingly engages the valve seat to block refrigerant flow from the valve inlet to the valve outlet, and the valve plug in the open position is spaced apart from the valve seat to permit refrigerant flow from the valve inlet to the valve outlet, the valve plug moves to the closed position in response to the pressure differential between the high-pressure side and the low-pressure side being below a predetermined limit, the valve plug moves toward the open position in response to the pressure differential between the high-pressure side and the low-pressure side being at least as great as the predetermined limit;d) a spring disposed within one of the piston chamber and the discharge chamber to urge the valve plug toward the valve seat;e) a stem guide disposed within the discharge chamber, the stem guide defines a fluid passageway connecting the piston chamber in fluid communication with the discharge chamber; andf) a valve stem slidingly disposed within the stem guide, the valve stem couples the piston to the valve plug such that movement of the piston within the piston chamber moves the valve plug relative to the valve seat. 2. The refrigerant system of claim 1, wherein the valve plug to a limited extent is axially movable relative to the valve stem. 3. The refrigerant system of claim 1, wherein the valve plug is pivotally attached to the valve stem. 4. The refrigerant system of claim 1, wherein the spring is disposed within the discharge chamber. 5. The refrigerant system of claim 1, wherein the valve plug moves between the closed position and the open position such that whenever the compressor is operating: a) in the open position, the discharge valve conveys refrigerant from the high-pressure side to the condenser,b) in the closed position, the discharge valve blocks refrigerant from flowing from the compressor to the condenser,c) refrigerant pressure at the high-pressure side continuously urges the discharge valve toward the open position, andd) the spring and refrigerant pressure at the low-pressure side continuously urges the discharge valve toward the closed position. 6. The refrigerant system of claim 1, wherein the compressor includes a screw rotor disposed within a compressor housing, the screw rotor has an axial face that rotates in proximity with a bearing housing axial face of the compressor housing, the bearing housing axial face is substantially parallel to the axial face of the screw rotor, the axial face of the screw rotor can rub against the bearing housing axial face under certain pressure conditions, the refrigerant pushes the axial face of the screw rotor away from the bearing housing axial face of the compressor housing when the pressure differential between the high-pressure side and the low-pressure side is at least as great as the predetermined limit. 7. The refrigerant system of claim 6, further comprising a rolling element bearing that supports the screw rotor within the compressor housing, the rolling element bearing allows the axial face of the screw rotor to rub against the bearing housing axial face of the compressor housing, the rolling element bearing allows the axial face of the screw rotor to move away from the bearing housing axial face in a spaced-apart relationship therewith, the rolling element bearing limits how far the axial face of the screw rotor can move away from the bearing housing axial face of the compressor housing. 8. The refrigerant system of claim 1, wherein the oil inlet of the compressor is at a pressure that is closer to that of the high-pressure side than that of the low-pressure side. 9. The refrigerant system of claim 1, wherein the compressor includes a screw rotor that upon some startups makes at least one revolution before the valve plug moves completely over to the open position. 10. The refrigerant system of claim 1, wherein the compressor includes a screw rotor that upon some startups makes at least one revolution while the valve plug remains in the closed position. 11. A refrigerant system circulating a refrigerant to create a high-pressure side and a low-pressure side, the refrigerant system comprising: a compressor that includes a compressor housing defining a discharge port at the high-pressure side, defining a suction port at the low-pressure side, and defining an oil inlet, the compressor being operable to compress the refrigerant to create a pressure differential between the high-pressure side and the low-pressure side, the compressor includes a screw rotor supported by a rolling element bearing within the compressor housing, the rolling element bearing allows an axial face of the screw rotor to rub against a bearing housing axial face of the compressor housing under certain pressure conditions, the rolling element bearing allows the axial face of the screw rotor to move away from the bearing housing axial face in a spaced-apart relationship therewith, the rolling element bearing limits how far the axial face of the screw rotor can move away from the bearing housing axial face of the compressor housing, the refrigerant pushes the axial face of the screw rotor away from the bearing housing axial face of the compressor housing when the pressure differential between the high-pressure side and the low-pressure side is at least as great as the predetermined limit;an oil separator defining a refrigerant inlet, a refrigerant outlet, and an oil outlet, wherein the refrigerant inlet is in fluid communication with the discharge port of the compressor;an oil return conduit connecting the oil outlet of the oil separator in fluid communication with the oil inlet of the compressor;an evaporator defining an evaporator inlet and an evaporator outlet, wherein the evaporator outlet is connected in fluid communication with the suction port of the compressor;a condenser defining a condenser inlet and a condenser outlet;an expansion device connecting the condenser outlet in fluid communication with the evaporator inlet; anda discharge valve defining a discharge chamber, a piston chamber, a valve inlet connected in fluid communication with the refrigerant outlet of the oil separator, a valve outlet connected in fluid communication with the condenser inlet, and a valve actuator port connected in fluid communication with the condenser inlet, the discharge valve comprises:a) a piston disposed within the piston chamber so as to substantially isolate the valve actuator port from the discharge chamber;b) a valve seat;c) a valve plug disposed within the discharge chamber and being movable relative to the valve seat between a closed position and an open position, wherein valve plug in the closed position sealingly engages the valve seat to block refrigerant flow from the valve inlet to the valve outlet, and the valve plug in the open position is spaced apart from the valve seat to permit refrigerant flow from the valve inlet to the valve outlet, the valve plug moves to the closed position in response to the pressure differential between the high-pressure side and the low-pressure side being below a predetermined limit, the valve plug moves toward the open position in response to the pressure differential between the high-pressure side and the low-pressure side being at least as great as the predetermined limit;d) a spring disposed within one of the piston chamber and the discharge chamber to urge the valve plug toward the valve seat;e) a stem guide disposed within the discharge chamber, the stem guide defines a fluid passageway connecting the piston chamber in fluid communication with the discharge chamber; andf) a valve stem slidingly disposed within the stem guide, the valve stem couples the piston to the valve plug such that movement of the piston within the piston chamber moves the valve plug relative to the valve seat. 12. The refrigerant system of claim 11, wherein the valve plug to a limited extent is axially movable relative to the valve stem. 13. The refrigerant system of claim 11, wherein the valve plug is pivotally attached to the valve stem. 14. The refrigerant system of claim 11, wherein the spring is disposed within the discharge chamber. 15. The refrigerant system of claim 11, wherein the valve plug moves between the closed position and the open position such that whenever the compressor is operating: e) in the open position, the discharge valve conveys refrigerant from the high-pressure side to the condenser,f) in the closed position, the discharge valve blocks refrigerant from flowing from the compressor to the condenser,g) refrigerant pressure at the high-pressure side continuously urges the discharge valve toward the open position, andh) the spring and refrigerant pressure at the low-pressure side continuously urges the discharge valve toward the closed position. 16. The refrigerant system of claim 11, wherein the oil inlet of the compressor is at a pressure that is closer to that of the high-pressure side than that of the low-pressure side. 17. The refrigerant system of claim 11, wherein the screw rotor upon some startups makes at least one revolution before the valve plug moves completely over to the open position. 18. The refrigerant system of claim 11, wherein the screw rotor upon some startups makes at least one revolution while the valve plug remains in the closed position.