A positive displacement roots blower can include a housing having an inlet structured to receive an incoming flow of a fluid, an outlet structured to receive an outgoing flow of the fluid, and a passage. The positive displacement roots blower can also include a pair of intermeshed rotating members supported for complementary rotation within the housing, where the rotating members and the housing form respective operating volumes there between which rotate with the rotating members. Each of the respective operating volumes has the following regions: (1) open to inlet/closed to outlet; (2) closed to inlet/closed to outlet; and (3) closed to inlet/open to outlet. The passage includes a restriction and connects to at least one of the operating volumes when the at least one of the respective operating volumes is in region (2). The restriction can be a venturi feedback connecting to the outlet.

An exhaust gas recirculation pump for an internal combustion engine that includes an electric motor assembly having an electric motor disposed within an electric motor housing. A roots device is coupled to the electric motor. The roots device includes a housing defining an internal volume. Rotors are disposed in the internal volume and connected to the electric motor. A bearing plate is attached to the housing wherein the bearing plate and an outer cover attached to the bearing plate defines an oil cavity. A transmission assembly is positioned on an opposing side of the housing relative to the electric motor and in the oil cavity.

A multi-stage positive displacement vacuum pump and a method of differentially pumping multiple vacuum chambers using such a pump is disclosed. The pump comprises a housing for housing at least one rotor mounted for rotation on a corresponding at least one shaft and for pumping gas through the multiple stages for output through an exhaust. The housing comprises a first inlet configured to admit gas to an inlet stage of said vacuum pump, and a further inlet configured to admit gas to an intermediate stage of said vacuum pump. The pump is configured such that gas admitted through each of the first and further inlets is pumped together as a combined gas flow by at least one stage of said vacuum pump downstream of said intermediate stage.

A dry-type primary vacuum pump includes an injection device to distribute a purging gas in the pumping stages. The injection device includes: a first pressure sensor arranged on a common portion of the distributor, a second pressure sensor arranged on each branch of the distributor, and a control unit to generate a pulse width modulation command signal for the control of the regulation valves independently of one another as a function of the pressure measurement differences between the first pressure sensor and the second pressure sensors.

A gas treatment device treats, at atmospheric pressure, the gases pumped by at least one rough pumping device. The gas treatment device includes a treatment chamber and at least one discharge pipe to connect a discharge of the at least one rough pumping device to an inlet of the treatment chamber. The gas treatment device further includes at least one auxiliary pumping device to lower the pressure in the at least one discharge pipe, situated less than 1 meter from the inlet of the treatment chamber, such as less than 50 cm.

A transmission structure of motor connection of roots pump comprises a shaft sleeve, a motor shaft cavity is opened inside the shaft sleeve, and the inner circle of the motor shaft cavity is concentrically meshed with the excircle of the motor shaft; a fixed bolt mounting cavity is opened on the outer surface of the shaft sleeve, a bolt through-hole is opened in the fixed bolt mounting cavity, the shaft sleeve is fixedly connected with the gear seat through a hexagon bolt, and the gear seat and the shaft sleeve rotate synchronously at the same shaft center; a gear is fixedly connected with the gear seat with a bolt, the gear seat is fixed to the pump shaft through a first keyway under the fitting between the first keyway and a first shaft key, and the pump shaft and the motor shaft are coaxially arranged at the center. The utility model overcomes the disadvantages of the prior art, which is convenient to install without wearing parts, not affected by temperature, pressure and external dust; and the structure is simple with compound seal and oil protection function; and when a motor with a motor shaft is selected, only the diameter and keyway of the motor shaft cavity of the part are required to fit the new motor.

A vacuum pump is provided that includes 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 multistage pump body comprises a first pumping chamber (20) and a second pumping chamber (21). A connecting duct (26a) puts an outlet (27) of the first pumping chamber (20) into communication with an inlet (28) of the second pumping chamber (21). A leak-tight conduit (40) is provided for the circulation of a cooling liquid. The connecting duct (26a) is a lateral duct of the multistage pump body. A heat-conducting wall (33) partially delimits the connecting duct (26a) and has an external surface (34) on the outside. At least a portion of the connecting duct (26a) passes between this external surface (34) of the heat-conducting wall (33) and the leak-tight conduit (40).

A multistage pump assembly with at least one co-used shaft comprises a first pump set including at least two vacuum chambers. Each vacuum chamber of the first pump set is installed with at least one rotor and a first driving shaft, the rotor is installed to the first driving shaft in the same vacuum chamber of the first pump set. The first driving shafts in the first pump set are co-shafted, that is, rotors in the at least two vacuum chambers of the first pump set are installed at the same first driving shaft. A second pump set includes at least one vacuum chamber which includes at least one rotor and a second driving shaft. An outlet of the second pump set is connected to an inlet of the first pump set through an air tube.

A rough-vacuum pump of dry type includes a duct formed in the stator and of which an inlet orifice is intended to be connected to at least one source of purge gas and of which at least one outlet orifice communicates with the last pumping stage communicating with the delivery and a device for injecting a heated purge gas including a heating device to at least partly heat the purge gas injected into the duct to a temperature higher than 40° C.