A vacuum pump comprises rotor elements arranged in a suction chamber. An outlet duct is connected to an exhaust pipe. For the purpose of silencing, sound expansion spaces are provided in the outlet duct, which are integrated into the pump housing. Alternatively or in addition to these sound expansion spaces, sound expansion spaces may be provided in an inlet duct which is used for the inlet of gas ballast, said sound expansion spaces being preferably likewise integrated into the pump housing.

A shunt-enhanced compression and pulsation trap (SECAPT) for a screw compressor assists internal compression (IC), reduces gas pulsation and NVH, and improves off-design efficiency, without using a slide valve and/or a serial pulsation dampener. The SECAPT includes an inner casing (e.g., an integral part of the compressor chamber) and an outer casing (e.g., surrounding part of the inner casing near the compressor discharge port) forming at least one diffusing chamber with a nozzle and a feedback region that provides a feedback flow loop between the compressor chamber and the compressor discharge port. The SECAPT automatically compensates cavity pressure to meet different outlet pressures (hence eliminating under-compression and/or over-compression when the discharge port opens), partially recovers potential energy associated with the under-compression (UC), and traps and attenuates gas pulsations and noise before the discharge port opens.

A compressor includes a compression mechanism to compress gas and discharge compressed gas, an electric motor to drive the compression mechanism, a casing housing the compression mechanism and the electric motor, a suction pipe connected to a suction side of the compression mechanism via the casing, and a discharge pipe provided at the casing to open in a space in the casing. The space has a first space located below the motor, and a second space located above the motor. The compression mechanism is disposed in the first space. The compressor is provided with a partition plate disposed in the second space, and the having a gas passage hole. The partition plate further has an oil drain hole formed at a lower level than an open end of the gas passage hole, and located radially outside an outer peripheral surface of a rotor of the electric motor.

A rotary compressor includes a compression mechanism having a cylinder, a piston, and a Helmholtz muffler. The Helmholtz muffler has a resonance chamber in the compression mechanism and a communication groove formed on an end face of the cylinder to connect the cylinder and resonance chambers. The communication groove is open at the end face of the cylinder and has a pair of side wall portions and a bottom wall portion between the side wall portions. Each side wall portion has a first portion adjacent an open end of the communication groove and a second portion adjacent the bottom wall portion. A surface of the first portion is a flat or bowed surface. A surface of the second portion is a bowed surface having a predetermined curvature so as to be connected to the surface of the first portion and a surface of the bottom wall portion.

A method of assembling a compressor system includes attaching at least two pulsation damper stages to a discharge port on a compressor, and attaching additional pulsation dampening stages if additional stages are desired. A compressor and discharge system is also disclosed.

Provided is a gear pump and a gear motor in which noise is reduced. A gear pump includes: gears which mesh and pair with each other; a casing including a gear housing chamber for housing the gears; and at least one hollow layer which is configured in the casing and divides the casing into at least inner walls and outer walls. Coincidence critical frequency of the inner walls and coincidence critical frequency of the outer walls are different. The hollow layer is formed between the gear housing chamber in the casing and an outer surface of the casing.

A silencer for vacuum pumps which allows only for unidirectional flow and which reduces the noises caused by the air discharged at the exhaust of said pump. The silencer features baffles to divert and disrupt the flow and an umbrella check valve to ensure the unidirectionality of the discharge flow.

A supercharger assembly comprises a housing, a rotor bore with an outer wall, an outlet in an outlet plane, an inlet in an inlet plane perpendicular to the outlet plane, and an outlet divider wall. The supercharger assembly comprises a first recess, a first perforated material covering the first recess, and an outlet resonator. The first recess is separated from the outlet by the outlet divider wall. The first recess is located between the outer wall and the first perforated material.

A compressor includes a compression chamber forming member, an injection passage, an injection pipe, and a pulsation attenuation space. The compression chamber forming member forms a compression chamber. The injection passage is formed in at least one of the compression chamber forming member and a separate member disposed in a surrounding area and connecting to the compression chamber. The injection pipe supplies refrigerant to the injection passage. The pulsation attenuation space is formed in one of the compression chamber forming member and the separate member disposed in the surrounding area so as to communicate with the injection passage. The pulsation attenuation space attenuates pulsation of refrigerant gas flowing from the injection pipe into the compression chamber.

A rotary compressor includes: a shell defining an internal space; a driving motor arranged in the internal space of the shell; and a compression mechanism unit to receive power of the driving motor and compress refrigerant, wherein the compression mechanism unit includes: a cylinder defining a chamber in which the refrigerant is compressed; a rotary shaft connected to the driving motor; a roller located in the chamber and connected to the rotary shaft to compress the refrigerant in the chamber while being rotated; a bearing coupled to the cylinder and having a discharge port through which the refrigerant compressed in the chamber passes; a muffler coupled to the bearing and into which the refrigerant passing through the discharge port is introduced; and a noise reducing unit fixed to the muffler to define a noise reducing chamber together with the muffler.