Abstract: A method of operating a multiple-compressor refrigeration system is provided. This method includes the steps of supplying, via a common supply line, refrigerant gas and oil to a plurality of compressors coupled in series, and attaching an oil flow conduit between adjacent compressors of the plurality of compressors. The oil flow conduit is configured to move oil from a compressor with a relatively higher pressure to a compressor with a relatively lower pressure. The method further includes controlling the pressure for each of the plurality of compressors by regulating a speed at which each of the plurality of compressors operates in order to maintain a pressure differential between the adjacent compressors to facilitate the flow of oil from the compressor with the relatively higher pressure to the compressor with the relatively lower pressure.

Abstract: A refrigeration system with two or more compressors configured to compress a flow of refrigerant with oil entrained therein. A suction flow piping arrangement is configured to supply a flow of refrigerant and oil to the two or more compressors. The suction flow piping arrangement has a suction header configured to carry the flow of refrigerant and oil, and a primary compressor supply conduit connected to the suction header. The primary compressor supply conduit supplies refrigerant and oil to a first compressor of the two or more compressors. A secondary compressor supply conduit branches off from the suction header. The secondary compressor supply conduit supplies refrigerant to a second compressor of the two or more compressors. The primary compressor supply conduit is configured to supply more oil to the first compressor than the secondary compressor supply conduit supplies to the second compressor.

Abstract: A refrigeration system with at least three compressors connected in a circuit. Each compressor has a housing with an oil sump. The oil sump is adapted to contain oil that defines an oil level. A supply line supplies refrigerant and entrained oil to each of the at least three compressors. The oil sump of each compressor has at least one oil port. Each oil port is disposed at an elevation that is equal to or minimally higher than the level of oil to promote equalization of oil levels in each compressor. There are a plurality of separate conduits which are not directly connected, but connected through the oil sumps of separate compressors. At least one compressor includes an oil sump extension having connections for the separate conduits. Each oil port is connected to the separate conduits or an oil sump extension. Each separate conduit connects a pair of compressors.

Abstract: A method of operating a refrigeration system having at least three compressors, in which each compressor has an oil sump with oil at an oil level. The method includes separately connecting the oil sumps of the at least three compressors. Each separate connection allows oil flow only between the oil sumps of two of said compressors thereby preventing bypass flow. The method further includes flowing oil between oil sumps of the at least three compressors and along the separate connections to tend to equalize the oil levels among the oil sumps of the at least three compressors.

Abstract: A refrigeration system with at least three compressors connected in a circuit. Each compressor has a housing with an oil sump. The oil sump is adapted to contain oil that defines an oil level. A supply line supplies refrigerant and entrained oil to each of the at least three compressors. The oil sump of each compressor has at least one oil port. Each oil port is disposed at an elevation that is equal to or minimally higher than the level of oil to promote equalization of oil levels in each compressor. There are a plurality of separate conduits which are not directly connected, but connected through the oil sumps of separate compressors. At least one compressor includes an oil sump extension having connections for the separate conduits. Each oil port is connected to the separate conduits or an oil sump extension. Each separate conduit connects a pair of compressors.

Abstract: A refrigeration system includes a plurality of compressors connected in series with each other. Each compressor has an oil sump located in a gravitational bottom of the compressor. A common supply line supplies refrigerant and oil to each of the plurality of compressors. The plurality of compressors includes a lead compressor and one or more non-lead compressors. The common supply line is configured to return more oil to the lead compressor than to the one or more non-lead compressors. Oil sump pressures for the plurality of compressors are maintained such that the lead compressor has the highest oil sump pressure, and the oil sump pressures of the non-lead compressors are successively lower with respect to its position downstream of the lead compressor. As a result, oil is distributed between adjacent compressors from the lead compressor, which is a most upstream compressor, sequentially downstream to the one or more non-lead compressors.

Abstract: A compressor for compressing fluid is provided. The compressor includes a housing having a housing inlet for receiving fluid and a housing outlet for discharging the fluid. A compressing mechanism is adapted to compress the fluid toward the housing outlet. The compressing mechanism is disposed in the housing. A drive unit is operatively connected to the compressing mechanism for driving the compressing mechanism to compress fluid. A suction duct is disposed in the housing. The suction duct extends vertically downward from the housing inlet toward a sump defined in the housing. The suction duct is configured for attachment to a motor housing. The suction duct has a duct inlet fluidically connected with the housing inlet, and defines a passage fluidically connecting the duct inlet with an interior cavity of the housing. A suction gas filter disposed in the suction duct, and having a filter screen positioned downstream of the duct inlet.

Abstract: A method of operating a multiple-compressor refrigeration system is provided. This method includes the steps of supplying, via a common supply line, refrigerant gas and oil to a plurality of compressors coupled in series, and attaching an oil flow conduit between adjacent compressors of the plurality of compressors. The oil flow conduit is configured to move oil from a compressor with a relatively higher pressure to a compressor with a relatively lower pressure. The method further includes controlling the pressure for each of the plurality of compressors by regulating a speed at which each of the plurality of compressors operates in order to maintain a pressure differential between the adjacent compressors to facilitate the flow of oil from the compressor with the relatively higher pressure to the compressor with the relatively lower pressure.

Abstract: A method of operating a refrigeration system uses a plurality of compressors in connected parallel. The method includes returning refrigerant and oil to the compressors, the refrigerant also having oil entrained therein, separating the oil entrained in the refrigerant, and returning more of the oil entrained in the refrigerant to a lead compressor of the plurality of compressors regardless of whether the lead compressor is operating. The method also includes connecting the oil sumps of all of the plurality of compressors such that oil is supplied from the lead compressor to at least one non-lead compressor of the plurality of compressors when the at least one non-lead compressor is operating.

Abstract: A refrigeration system includes a plurality of compressors connected in series with each other. Each compressor has an oil sump located in a gravitational bottom of the compressor. A common supply line supplies refrigerant and oil to each of the plurality of compressors. The plurality of compressors includes a lead compressor and one or more non-lead compressors. The common supply line is configured to return more oil to the lead compressor than to the one or more non-lead compressors. Oil sump pressures for the plurality of compressors are maintained such that the lead compressor has the highest oil sump pressure, and the oil sump pressures of the non-lead compressors are successively lower with respect to its position downstream of the lead compressor. As a result, oil is distributed between adjacent compressors from the lead compressor, which is a most upstream compressor, sequentially downstream to the one or more non-lead compressors.

Abstract: A compressor for compressing fluid is provided. The compressor includes a housing having a housing inlet for receiving fluid and a housing outlet for discharging the fluid. A compressing mechanism is adapted to compress the fluid toward the housing outlet. The compressing mechanism is disposed in the housing. A drive unit is operatively connected to the compressing mechanism for driving the compressing mechanism to compress fluid. A suction duct is disposed in the housing. The suction duct extends vertically downward from the housing inlet toward a sump defined in the housing. The suction duct is configured for attachment to a motor housing. The suction duct has a duct inlet fluidically connected with the housing inlet, and defines a passage fluidically connecting the duct inlet with an interior cavity of the housing. A suction gas filter disposed in the suction duct, and having a filter screen positioned downstream of the duct inlet.

Abstract: A method of operating a refrigeration system, that includes providing a plurality of compressors connected in parallel. The plurality of compressors includes a plurality of scroll compressors. The method further includes returning circulated refrigerant to the plurality of compressors, the circulated refrigerant having oil entrained therein. Returning circulated refrigerant to the plurality of compressors includes returning more oil to one of the plurality of compressors than to another of the plurality of compressors. The method also includes supplying oil from one of the plurality of compressors to at least one other of the plurality of compressors. Supplying oil from one of the plurality of compressors includes supplying oil from the one of the plurality of compressors having an opening in its housing. A fitting is assembled into the opening. The fitting protrudes through the housing into an interior portion of the housing.

Abstract: A method of operating a refrigeration system, that includes providing a plurality of compressors connected in parallel. The plurality of compressors includes a plurality of scroll compressors. The method further includes returning circulated refrigerant to the plurality of compressors, the circulated refrigerant having oil entrained therein. Returning circulated refrigerant to the plurality of compressors includes returning more oil to one of the plurality of compressors than to another of the plurality of compressors. The method also includes supplying oil from one of the plurality of compressors to at least one other of the plurality of compressors. Supplying oil from one of the plurality of compressors includes supplying oil from the one of the plurality of compressors having an opening in its housing. A fitting is assembled into the opening. The fitting protrudes through the housing into an interior portion of the housing.

Abstract: A refrigeration system with two or more compressors configured to compress a flow of refrigerant with oil entrained therein. A suction flow piping arrangement is configured to supply a flow of refrigerant and oil to the two or more compressors. The suction flow piping arrangement has a suction header configured to carry the flow of refrigerant and oil, and a primary compressor supply conduit connected to the suction header. The primary compressor supply conduit supplies refrigerant and oil to a first compressor of the two or more compressors. A secondary compressor supply conduit branches off from the suction header. The secondary compressor supply conduit supplies refrigerant to a second compressor of the two or more compressors. The primary compressor supply conduit is configured to supply more oil to the first compressor than the secondary compressor supply conduit supplies to the second compressor.

Abstract: A method of operating a refrigeration system having at least three compressors, in which each compressor has an oil sump with oil at an oil level. The method includes separately connecting the oil sumps of the at least three compressors. Each separate connection allows oil flow only between the oil sumps of two of said compressors thereby preventing bypass flow. The method further includes flowing oil between oil sumps of the at least three compressors and along the separate connections to tend to equalize the oil levels among the oil sumps of the at least three compressors.

Abstract: A method of operating a refrigeration system uses a plurality of compressors in connected parallel. The method includes returning refrigerant and oil to the compressors, the refrigerant also having oil entrained therein, separating the oil entrained in the refrigerant, and returning more of the oil entrained in the refrigerant to a lead compressor of the plurality of compressors regardless of whether the lead compressor is operating. The method also includes connecting the oil sumps of all of the plurality of compressors such that oil is supplied from the lead compressor to at least one non-lead compressor of the plurality of compressors when the at least one non-lead compressor is operating.

Abstract: A compressor (20) has a housing (22) having first (52) and second (48) members. A motor (24) within the housing (22) is coupled to one or more working elements (26, 28) to drive the one or more working elements (26, 28) to compress a fluid. A number of electrical terminals (104) are each mounted in an associated aperture (132) in the second housing member (48) and electrically connected to the motor (24).

Abstract: A screw compressor (10) comprises a housing (12, 14, 16), a slide valve assembly (23) and a pulsation damper. The housing (12, 14, 16) receives a supply of working matter from a pair of intermeshing screw rotors (18, 20), and comprises a slide recess (51), a pressure pocket (32), and a piston cylinder (54). The slide valve assembly (23) regulates the capacity of the screw compressor (10), and comprises a slide valve (36) axially movable within the slide recess (51) and the pressure pocket (32), a piston head (40) axially movable within the piston cylinder (54), and a piston shaft (38) connecting the slide valve (36) with the piston head (40). The pulsation damper comprises a flange (58) for separating the pressure pocket (32) from the piston cylinder (54), a bore (60) for receiving the piston rod (38), and a damping channel (46A) extending through the flange (58).

Abstract: A three rotor screw compressor is provided with a bearing cover, and an integral discharge case having a divider wall formed integrally with the bearing cover. The bearing cover closes bearing chambers for each of three rotor shafts, and the divider wall divides a plenum into two distinct chambers. By providing the divider wall, noise and efficiency losses from intermixing of two discharge flows from two separate compression chambers is eliminated. By forming a divider wall integrally with the bearing cover, leakage which has existed in the prior art is eliminated.

Abstract: A screw compressor has a housing (22; 302) having first (53; 330) and second (58; 340) ports along a flowpath. A first rotor (26; 306) has a lobed body. A second rotor (28; 308, 310) has a lobed body enmeshed with the first rotor body. The rotors and housing cooperate to define a compression path between suction (60; 332) and discharge (62; 342) locations along the flowpath. Means (100, 110, 120; 200, 210, 220; 370, 380, 390) provide relative longitudinal movement between a blocking portion (57; 352) of the housing and at least one of the first rotor and second rotor between: a first condition wherein a pocket of the first and second rotors is closed by the blocking portion; and a second condition wherein the blocking portion does not close the pocket. To provide capacity control, a control system (110; 390) is configured to provide duty cycle control of the movement.