A dry type primary vacuum pump is provided, including at least two pumping stages mounted in series between a suction and a discharge of the pump; two rotors extending in the pumping stages and being configured to rotate synchronously in a reverse direction to drive a gas to be pumped between the suction and the discharge; an injection device configured to distribute a purge gas in at least one pumping stage, the injection device including at least one injector and at least one injection valve with an on or off control configured to be interposed between a purge gas supply source and the injector; and a control device configured to control opening and closing of the injection valve to inject a purge gas by successive pulses into the at least one pumping stage. A method for controlling the injection of a purge gas the vacuum pump is also provided.

A gas compressor includes inverters, a plurality of compressor units and a control device for controlling each of the inverters. The control device increases the number of compressor bodies to be operated after confirming that the rotational speed of the operational motors will reach a steady value immediately after causing the number of the compressor bodies to be operated to increase.

A dry vacuum pump includes: at least one oil sump; at least one pumping stage; two rotary shafts respectively supporting at least one rotor extending into the at least one pumping stage, the rotors being configured to rotate in a synchronized manner in the reverse direction in order to convey a gas to be pumped between an intake and an outlet of the vacuum pump, the shafts being supported by bearings lubricated by a lubricant contained in the at least one oil sump; at least one lubricant sealing device interposed between the at least one oil sump and a pumping stage at the shaft passage; and at least one expansion device configured to reduce the pressure variations between a pumping side volume and the at least one oil sump.

According to one embodiment, a crank portion is formed from a crank piece, an element separate from a shaft portion. The crank piece includes a fitting hole in which the shaft portion is fit by predetermined “interference” and a slit-like slot with one end opened in an inner circumferential surface of the fitting hole, and an other end closed inside the crank piece. The fitting hole is deformed so as to expand its diameter when expanding a width of the slot. The shaft portion is fit in the fitting hole of the crank piece by the predetermined “interference” when inserted in the deformed fitting hole and the fitting hole restores an original form while the shaft portion is in the fitting hole.

A dry vacuum pump includes an elastic outer seal and at least one elastic inner seal respectively including a first and a second end annular parts parallel to one another and inserted between a respective end piece and the half-shells, and two side rails connecting the end annular parts and which are at right angles thereto, the side rails being inserted between the half-shells, the at least one inner seal being arranged inside the outer seal so that the at least one inner seal and the outer seal form at least two successive sealing barriers for the gases.

A vacuum system having a condenser and a root vacuum pump set includes an independent inlet condenser set having an inlet end for receiving vapor inputted from an output of an air cooling power generator condenser of a generator; air in the vapor being condensed, and the surplus air is outputted; a root vacuum pump set including at least one root vacuum pump; the root vacuum pump set further including an input end and an output end; the input end being connected to the independent inlet condenser set; air outputted from the independent inlet condenser set being inputted to the at least one root vacuum pump for compression and then the compressed air being outputted from the output end; and a backing pump connected to the output end of the root vacuum pump set by using an output pipe; the backing pump serving to receive air outputted from the root vacuum pump set.

Some embodiments of the present disclosure provide a compressor and an air conditioner with the compressor. The compressor includes: a first compression part, a second compression part, an intermediate cavity and an intermediate passage. Refrigerant discharged from the first compression part enters the intermediate cavity. The intermediate passage communicates with the intermediate cavity and an inner cavity of the second compression part. A bottom port of the intermediate passage is located at a bottom of the intermediate cavity, and air supplement refrigerant and/or the refrigerant discharged from the first compression part are used to convey accumulated oil in the intermediate cavity to the inner cavity of the second compression part. When only the refrigerant is used to convey the accumulated to the inner cavity of the second compression part, at least a part of the intermediate passage is located outside of a housing assembly of the compressor.

A lower end plate cover is provided with a bulging portion. In a circumferential direction of a rotary shaft, a plurality of bolt holes includes a first bolt hole arranged between a distal end portion and a proximal end portion of the lower discharge valve, a second bolt hole arranged in a position adjacent to the first bolt hole on a side close to a lower vane groove with respect to the first bolt hole, and a third bolt hole arranged in a position adjacent to the first bolt hole on a side away from the lower vane groove with respect to the first bolt hole. When the bulging portion is divided into a first bulging portion and a second bulging portion using a first straight line, the first bulging portion is larger than the second bulging portion.

A multistage compressor system with intercooler can include a sealed housing with first and second compressor stages, where the first compressor stage is for receiving refrigerant from outside of the sealed housing, and the second compressor stage is for receiving refrigerant from within the sealed housing. The compressor system can also include a crank for mechanically driving the first compressor stage and/or the second compressor stage, and a heat exchanger outside of the sealed housing for receiving refrigerant from the first compressor stage and exchanging heat with the refrigerant. The compressor system can further include an oil reservoir contained by the sealed housing, where the oil reservoir includes oil for lubricating the crank, receives the refrigerant from the heat exchanger, and exchanges heat with the refrigerant to cool the oil in the oil reservoir, and where the refrigerant can be supplied to the second compressor stage.

A rotary compressor includes a first cylinder, a first piston and a drive shaft. The drive shaft includes a first eccentric portion, a first shaft portion rotatably supported by a first bearing, and a first coupling portion coupling the first shaft portion with the first eccentric portion. The first piston is fitted to the first eccentric portion. The first shaft portion has a cylindrical shape coaxial with the rotational center axis. R.sub.e1−e.sub.1<R.sub.1. R.sub.e1 is a radius of the first eccentric portion. R.sub.1 is a radius of the first shaft portion. e.sub.1 is an eccentricity of the first eccentric portion. An outer surface of the first coupling portion does not extend radially out of the outer surface of the first eccentric portion. A circumferentially extending groove is formed at an end of an inner peripheral surface of the first piston on a first coupling portion side in the axial direction of the drive shaft.