A variable displacement pump includes: a first pressure control chamber; a second pressure control chamber; a spring arranged to urge the cam ring in a econd swing direction; a hydraulic pressure supply valve arranged to be opened by a predetermined hydraulic pressure, and thereby to introduce a control hydraulic pressure to the first control chamber; a connection passage formed in the housing or the cam ring, and arranged to connect the first pressure control chamber and the second pressure control chamber; and a relief circuit arranged to connect the second pressure control chamber and a low pressure side, to be opened or closed in accordance with a swing position of the cam ring, and to be closed when the cam ring is swung by a predetermined amount in the first direction.

An oil supply groove 12 in communication with a pump room 2A is formed above a bearing 2B of a housing 2, and an open air groove 14 in communication with an atmospheric air is formed at a position rotated around the bearing 2B by 90° from the oil supply groove. In a shank 3B of a rotor 3, a branch passage 11a branching from an oil passage 11 formed in its axial direction to the diametrical direction of the shank, and an open air passage 13 formed in the direction perpendicular to the branch passage are formed.

Then, the branch passage and the oil supply groove communicate with each other, at the same time, the open air passage and the open air groove are arranged to also communicate with each other, and when the oil passage and the oil supply groove communicate with each other as the rotor stops, then an atmospheric air flowing in from the open air passage eliminates a negative pressure in the pump room, thereby the lubricating oil is prevented from flowing into the pump room in large quantities.

An amount of the lubricating oil flowing into pump room at stop of the rotor can be reduced to prevent the vane from being damaged and an amount of the lubricating oil consumed due to rotation of the rotor can be controlled.

It is an object of the present invention to improve the reliability of a compressor by appropriately measuring the temperature inside the compressor. A compressor pertaining to the present invention is equipped with a casing (10), a compression mechanism (15), a drive shaft (17), a main frame (23), a motor (16), a flow path forming member (91), and a temperature measuring mechanism (76). The casing stores lubricating oil in its bottom portion. The compression mechanism compresses refrigerant. The drive shaft drives the compression mechanism. The main frame has the compression mechanism placed on it and supports the drive shaft in such a way that the drive shaft may freely rotate. The motor drives the drive shaft. The flow path forming member forms an oil flow path (92). The oil flow path is a space located in the neighborhood of an inner peripheral surface of the casing and through which lubricating oil that lubricates sliding portions including the compression mechanism and the drive shaft flows. The temperature measuring mechanism is disposed outside the casing. The temperature measuring mechanism measures the temperature of a section of an outer peripheral surface of the casing positioned in the neighborhood of the oil flow path.

It is an object of the present invention to provide a scroll compressor for easily measuring temperature of refrigerant flowing through a passage. A scroll compressor (1) includes a casing (11), a compression mechanism (15) and a pipe (71). A space (45) is provided in the interior of the casing (11). The space (45) functions as a refrigerant passage. The compression mechanism (15) is configured to compress the refrigerant and discharge it to the space (45) through a discharge port (41). The pipe (71) extends from the inside to the outside of the casing (11). The pipe (71) includes two ends. One is an end (71a) and the other is an end (71b). The end (71a) is a closed end disposed in a predetermined position in the space (45), specifically in a close position to the discharge port (41). The end (71b) is an opened end disposed outside the casing (11). A measuring instrument (8) is inserted into the pipe (71) through the end (71 b).

The hermetic type compressor 100 according to the present invention comprises, inside ahermetic container 1, a compressing mechanism portion 20 and an electric motor 10 for driving the compressing mechanism portion 20, and performs compression of the refrigerant continuously by dividing a compression room with a vane into a high-pressure room and a low-pressure room. The compression room is composed of a cylinder 16 that disposes therein a rolling piston 7 fitted to an eccentric axis 6a of the crankshaft 6 rotated by the electric motor 10, and a cylinder head 4 and a frame 5 that block both ends of the cylinder 16 in an axial direction. According to the hermetic type compressor 100 using the HC refrigerant, the electric motor is fitted and fixed to an inner peripheral plane of the hermetic container. An outer diameter of the electric motor is less than an outer diameter of the compressing mechanism portion. For the cylinder having an inner diameter D and a height H, D/H is set to more than 0.5 and less than 0.6.

The object of the present invention is to provide equipment that has complete safety against leakage of refrigerants from pin holes produced on a compressor that is intended for refrigerating air conditioners using refrigerants that are heavier than air and flammable.

A junction 5a of a hermetic container, where pin holes are most likely to be formed, is arranged to be located below a control box 28 which has the possibility of becoming a source of ignition.

The mixture ratio between air and refrigerants that might leak from pin holes produced in the welded junction 5a and the like of a hermetic container 2 of a hermetic compressor 1 is prevented from reaching a ratio where ignition takes place inside of an air conditioner.

As a result, a refrigerating air conditioner having complete safety is realized.

A method including: determining a cooling value; and comparing the cooling value to an activation point of a lead compressor. The lead compressor is in a tandem set of scroll compressors of a cooling system. The tandem set of compressors comprises a lag compressor. The method further includes: activating the lead compressor when the cooling value is greater than the activation point; activating the lag compressor subsequent to activating the lead compressor; and determining whether conditions exist including: an alarm associated with the lag compressor being generated, and the lead compressor being deactivated. The method further includes deactivating the lag compressor when at least one of the conditions exists in the cooling system.

A sliding vane vacuum pump includes a casing (10) having a cover which together define a cavity (12), a rotor and a vane slidably mounted to said rotor. The pump further includes an inlet passage (24) extending from the exterior of the pump to the cavity (12) and an outlet passage (20) extending from the cavity (12) to the exterior of the pump. The pump further includes an oil relief arrangement operable to vent lubricating oil to the exterior of the pump in the event of reverse rotation of the rotor and vane.