A sound suppression system for reducing or eliminating sound produced by the operation of a breast vacuum pump includes a sound suppressing muffler assembly having an air entry port adapted to communicate with an air outlet port of a vacuum pump or other air flow generating device. The sound suppressing muffler assembly also includes a muffler housing defining an internal space communicating with the air entry port, and an opening in the housing leading to atmosphere. The muffler housing has a tortuous air path in the muffler housing. In one embodiment, sound absorbing porous foam structure is disposed in the tortuous air path. The at least one sound absorbing porous structure absorbs sound energy from the air as the air moves through the at least one air path toward the opening in the muffler housing. In further embodiments, a tortuous air path is provided between an air entry port and an opening to atmosphere in the muffler assembly.

The invention provides an sliding contact single vane rotary vacuum pump in which an oil supply passage is placed in the centre of the rotating vane through which a lubricating oil flows, which provides oil distribution in the pump chamber with enhanced suction pressure of 39%; and the torque exertion by 2.86-7.63%, this helps in reducing the torque of the pump during maximum vacuum condition and results in reduction of the power consumption of the vacuum pump which in-turn decreases the net load on the automotive engine, thus reduces the peak torque, the pump internal chamber pressure and also results better vacuum suction performance.

A piston is arranged to move in a cylinder to define a variable volume chamber, and can expand in two directions under the influence of pressure in the variable volume chamber to provide sealing against the cylinder. The piston can comprise a primary foot and a secondary foot arranged to move relative to each other in a first direction. The primary foot and the secondary foot can each comprise plural segments arranged to move relative to each other in a second direction. The piston may be suitable for use in an inner rotor, where it forms the end of a projection of the inner rotor and fully exits and reenters the cylinders.

A compressor or vacuum pump including: a casing having a cooling gas inlet and a cooling gas outlet for allowing a cooling gas to flow therethrough; a fan mounted at the cooling gas inlet, including a fan housing and configured to blow said cooling gas into said casing; a compression or vacuum chamber including a first housing, a process gas inlet and outlet for allowing a process gas to flow therethrough and at least one rotating element; a driving module including a second housing and at least one bearing for supporting said at least one rotating element; a silencer including a cover and configured to attenuate noise generated by the compressor or vacuum pump. The silencer includes a recess structure on its cover, configured to deflect the cooling gas flow from the fan towards the driving module.

A pump cooling system may include a cooling body configured to be fitted to a pump housing to receive heat from the pump housing via a heat conducting path between the cooling body and pump housing. The cooling body may have a passage through which, in use, a cooling fluid is passed to conduct heat away from the cooling body. The pump cooling system includes a cooling control mechanism configured to provide a gap in the heat conducting path at pump operating temperatures below a predefined temperature so heat conduction from the pump housing to the cooling body is interrupted.

A leak detector is provided for leak-testing objects that are to be tested by spraying tracer gas, the leak detector including: a detection inlet configured to be connected to an object that is to be tested; a pumping device including a vacuum line connected to the detection inlet, a rough-vacuum pump connected to the vacuum line, and a turbomolecular vacuum pump connected to the vacuum line, a delivery of which is connected to the rough-vacuum pump; and a gas detector connected to the turbomolecular vacuum pump, the pumping device further including an ancillary pump connected to the rough-vacuum pump and being configured to lower an ultimate-vacuum pressure of tracer gas in the rough-vacuum pump. A leak detection method for leak-testing objects that are to be tested by spraying tracer gas is also provided.

A pumping unit is provided, including a primary vacuum pump of a multistage dry type, including at least four pumping stages fitted in series; and a two-stage Roots vacuum pump, including a first pumping stage and a second pumping stage fitted in series, the second pumping stage being fitted in series with and upstream of a first pumping stage of the primary vacuum pump in a direction of flow of gases to be pumped, in which a ratio of a volume displacement of the first pumping stage of the two-stage Roots vacuum pump to a volume displacement of the second pumping stage of the two-stage Roots vacuum pump is less than six, and in which a ratio of a volume displacement of the second pumping stage of the two-stage Roots vacuum pump to a volume displacement of the first pumping stage of the primary vacuum pump is less than six.

An oil-injected vacuum pump element, where two mating helical rotors are rotatably provided in a housing, where this housing includes an inlet port and an outlet end face with an outlet port, where compression chambers are formed between the helical rotors and the housing. The vacuum pump element is provided with a connection that extends from a first compression chamber to a second smaller compression chamber at the outlet end face, where this first compression chamber is at a lower pressure than the second compression chamber and where this second compression chamber can make connection with the outlet port upon rotation of the helical rotors, where the connection is such that a flow from the second compression chamber to the first compression chamber is possible, where the connection is not directly connected to the outlet port.

A vacuum pump suitable for mounting to an engine includes: a casing having a cavity, the cavity including an inlet and an outlet; a moveable member arranged for rotation inside the cavity, the movable member being movable to draw fluid into the cavity through the inlet and out of the cavity through the outlet so as to induce a reduction in pressure at the inlet; a valve seat at the outlet; and an outlet valve including a reed element and a stop for restricting movement of the reed element. The stop is movable between a first operating position, in which movement of the reed element is restricted to a first opening degree, and a second start-up position, in which movement of the reed element is restricted to a second opening degree, which is larger than the first opening degree.

A vacuum pump comprises: a rotary body including a rotor blade and a rotor shaft; a case rotatably housing the rotary body; a motor configured to drive the rotor shaft of the rotary body; a bearing arranged at an end portion of the rotor shaft; and at least three balance correction portions including a first balance correction portion provided on one end side of the rotary body in an axial direction, a second balance correction portion provided on the other end side of the rotary body in the axial direction, and a third balance correction portion provided between the first balance correction portion and the second balance correction portion. Balance correction by an n-plane method, where n 3, is available such that any of the three balance correction portions is accessible from an outside of the case.