A plurality of scroll compressors with different fixed volume indexes are connected in fluid parallel circuit and configured to selectively operate to maximize isentropic efficiency at different condensing temperatures. Different quantities of scroll compressors of different volume indexes may be selected based upon typical climate or geographic location environmental conditions to attempt to maximize efficiency. A controller may selectively operate different combinations of the compressors of different volume indexes bases up load demands and condensing temperature conditions, which may be determined in a variety of ways.

A plurality of scroll compressors with different fixed volume indexes are connected in fluid parallel circuit and configured to selectively operate to maximize isentropic efficiency at different condensing temperatures. Different quantities of scroll compressors of different volume indexes may be selected based upon typical climate or geographic location environmental conditions to attempt to maximize efficiency. A controller may selectively operate different combinations of the compressors of different volume indexes bases up load demands and condensing temperature conditions, which may be determined in a variety of ways.

A manufacturing method of an end plate of a pump that can remove a sag includes: punching a workpiece from a plate material, the workpiece being the end plate including a mounting seat including a fastener; forming a pressed trace surface by pressing an outer edge of an outer surface, when a surface, of both front and back surfaces of the punched workpiece, further from a sag formed on a cut end surface is the outer surface, and a surface, of both front and back surfaces of the punched workpiece, nearer to the sag is an inner surface. A section of the pressed trace surface disposed along an outer edge of the mounting seat is a fastening section. A section of the pressed trace surface other than the fastening section is a non-fastening section. A radial width of the fastening section is shorter than that of the non-fastening section.

A rotary compressor including a cylindrical compressor housing provided with an inlet unit of a refrigerant and a discharging unit of the refrigerant, a compressing unit which is disposed inside the compressor housing and includes a cylinder and a piston for compressing the refrigerant sucked in from the inlet portion, a rotation shaft provided with the piston of the compressing unit, and a motor which includes a cylindrical stator and a rotor that is provided on another end side of the rotation shaft and that rotates inside the stator, and which drives the compressing unit via the rotation shaft, in which an outer circumferential portion of the stator includes a concave portion and is fixed to an inner circumferential portion of the compressor housing in a transition fit state, and in which the compressor housing includes a weld portion which is joined to the concave portion of the stator.

The height measured from the bottom surfaces of support legs is set to be 2.5 or more times as great as the outer diameter of the compressor body, the height of the center of gravity measured from the bottom surfaces of the support legs to the center of gravity is set to be ½ or less the overall height, and the support legs are provided in number of four, based on the fulfillment of Rc/cos θ<Rb<L. Here Rb is the support point radius of the compressor body, Rc is the outer radius of the compressor body, L is the distance from a longitudinal central axis of the compressor body to a longitudinal central axis of an accumulator, and θ is an angle half the angle formed between the adjacent support legs about the central axis.

A gearbox system for a rotorcraft includes a gearbox housing, an oil pump receiving bore formed into the gearbox housing and having formed therein a first opening having a first diameter and a second opening, and an oil pump positioned within the oil pump receiving bore. The second opening is bounded by a lip that extends radially into the second opening, the second opening having a second diameter that is smaller than the first diameter.

The cluster block accommodates connection terminals and has conductive member insertion holes, into which the conductive members are inserted. The cluster block is disposed between the bottom wall of the housing and second coil ends. The conductive member insertion holes are located on the radially outer side of the inner circumferential surface of the stator core. The cluster block includes a second wall portion in the vicinity of the electric motor and a first wall in the vicinity of the bottom wall of the housing. The second wall portion has a pressed surface on the radially inner side of the inner circumferential surface of the stator core. The outer surface of the first wall portion has a contact surface that is lined up with the pressed surface in the axial direction of the stator core. The contact surface is allowed to contact the bottom wall of the housing.

A gearbox system for a rotorcraft includes a gearbox housing, an oil pump receiving bore formed into the gearbox housing and having formed therein a first opening having a first diameter and a second opening, and an oil pump positioned within the oil pump receiving bore. The second opening is bounded by a lip that extends radially into the second opening, the second opening having a second diameter that is smaller than the first diameter.

A manufacturing method of an end plate of a pump that can remove a sag includes: punching a workpiece from a plate material, the workpiece being the end plate including a mounting seat including a fastener; forming a pressed trace surface by pressing an outer edge of an outer surface, when a surface, of both front and back surfaces of the punched workpiece, further from a sag formed on a cut end surface is the outer surface, and a surface, of both front and back surfaces of the punched workpiece, nearer to the sag is an inner surface. A section of the pressed trace surface disposed along an outer edge of the mounting seat is a fastening section. A section of the pressed trace surface other than the fastening section is a non-fastening section. A radial width of the fastening section is shorter than that of the non-fastening section.

A method for decoupling a liquid ring pump component from a liquid ring pump for facilitating maintenance services, the liquid ring pump comprising a housing defining an annular chamber and a shaft passing into the chamber, the component being disposed around the shaft and coupled between the shaft and the housing, the method comprising: coupling, using a first fixing member, a first end of the shaft to the housing thereby to prevent or oppose movement of the shaft relative to the housing in at least a radial direction; and, thereafter, sliding the component along the shaft in a direction along the shaft from the housing towards the first end of the shaft, thereby spacing apart the housing and the component.