The invention relates to a single-stage or multistage suction jet pump comprising a propelling nozzle (5), one or more suction nozzles (2), a diffuser (7), and a volume flow limiting valve in or directly in front of the propelling nozzle. The volume flow limiting valve has a valve element (4) in the overpressure region (1) of the suction jet pump, said valve element having an opening (8) with a cross-sectional area which is smaller than the cross-sectional area of the propelling nozzle (5). The valve element spans at least one additional gap opening (9) which first releases the cross-section of the gap opening (9) when the pressure difference between the overpressure region (1) and the suction region (2) increases and which switches in the event of a defined large pressure drop and the valve element (4) reduces or closes the cross-section of the gap opening (9) such that the volume flow flowing over the opening (8) is limited to a defined level even in the event of a further increasing pressure difference.

A vacuum-keeping multistage vacuum-generating and vacuum-destructing valve includes a main body, which includes an introduction port, a vacuum port, a discharge port, and a vacuum-generating valve, in combination with a vacuum-destructing valve. The vacuum-destructing valve is arranged in combination with a flow conducting passage formed in the main body and connected to the vacuum port to allow a pressure fluid received through the introduction port to partly flow through the vacuum-destructing valve, and a vacuum-destructing two-port two-position valve is arranged in the flow conducting passage to increase flow rate of the pressure fluid passing therethrough to make a response of the vacuum port more sensitive in switching to a vacuum-destructing state. The ports of the main body are arranged in a detachable manner to increase service efficiency and ease part replacement. Two side seats are arranged to couple multiple such main bodies together to cope with complicated automatic processing operations.

A device for evacuating a film chamber using a pump system that comprises at least two vacuum pumps, designed to evacuate the film chamber alternately. A suction capacity of the first vacuum pump is greater than that of the second vacuum pump and the final pressure achievable by the first vacuum pump is less than that of the second vacuum pump.

A device for evacuating a film chamber using a pump system that comprises at least two vacuum pumps, designed to evacuate the film chamber alternately. A suction capacity of the first vacuum pump is greater than that of the second vacuum pump and the final pressure achievable by the first vacuum pump is less than that of the second vacuum pump.

A purge system for fuel evaporation gas may include an ejector, having a nozzle configured to allow driving fluid to pass therethrough, a driving inlet through which the driving fluid is supplied into the ejector, a suction inlet through which purge gas including a fuel component is drawn as suction fluid from a canister into the ejector, a diffuser outlet through which a mixture of the driving fluid that has passed through the nozzle and the drawn purge gas is discharged out of the ejector, and a suction passage extending from the suction inlet toward a downstream side of the nozzle based on a flow direction of the driving fluid, and a bypass passage coupled from the suction inlet to the driving inlet.

A multistage ejector is provided for generating a vacuum from a source of compressed air. The compressed air is passed through a series of nozzles, which entrains air so as to form a jet flow in two or more stages and generating a vacuum across each stage. The ejector outlet is formed as a nozzle extending to the outlet end of the ejector and arranged to receive the jet flow from the final stage of the ejector. The ejector outlet nozzle includes a diverging section extending at an angle of divergence to the direction of airflow, the diverging section terminating in a stepwise expansion in the cross-sectional flow area, as viewed in a direction perpendicular to the direction of airflow through the ejector outlet nozzle.

A multistage ejector is provided for generating a vacuum from a source of compressed air. The compressed air is passed through a series of nozzles, which entrains air so as to form a jet flow in two or more stages and generating a vacuum across each stage. The ejector outlet is formed as a nozzle extending to the outlet end of the ejector and arranged to receive the jet flow from the final stage of the ejector. The ejector outlet nozzle includes a diverging section extending at an angle of divergence to the direction of airflow, the diverging section terminating in a stepwise expansion in the cross-sectional flow area, as viewed in a direction perpendicular to the direction of airflow through the ejector outlet nozzle.

A multi-stage ejector for generating a vacuum from a source of compressed air or fluid by passing the compressed air or fluid through a series of nozzles, accelerating and entraining the compressed air or fluid so as to form a jet flow in one or more stages and generate a vacuum across each stage. The multi-stage ejector may include a first drive stage; a second stage; and a converging-diverging nozzle provided in the series of nozzles between the first drive stage and the second stage. The multi-stage ejector, in use, may receive jet flow from the first drive stage, accelerate the jet flow to form a second stage air jet and direct the second stage air jet into an inlet of an outlet nozzle of the second stage. The converging-diverging nozzle may be formed in a molded nozzle piece mounted in the multi-stage ejector.

A multi-stage ejector for generating a vacuum from a source of compressed air or fluid by passing the compressed air or fluid through a series of nozzles, accelerating and entraining the compressed air or fluid so as to form a jet flow in one or more stages and generate a vacuum across each stage. The multi-stage ejector may include a first drive stage; a second stage; and a converging-diverging nozzle provided in the series of nozzles between the first drive stage and the second stage. The multi-stage ejector, in use, may receive jet flow from the first drive stage, accelerate the jet flow to form a second stage air jet and direct the second stage air jet into an inlet of an outlet nozzle of the second stage. The converging-diverging nozzle may be formed in a molded nozzle piece mounted in the multi-stage ejector.

The invention provides an ejector for generating a vacuum, a drive nozzle for generating a drive jet of air from a compressed air source and directing the drive jet of air into an outlet flow passage at the outlet of a drive stage of the ejector to entrain air in a volume surrounding the jet of air into the jet flow to generate a vacuum across the drive stage. The drive nozzle substantially consists of an inlet flow section and an outlet flow section aligned in a direction of air flow through the nozzle. The outlet flow section diverging in the direction of airflow, from an outlet end of the inlet flow section to an exit of the nozzle, the outlet flow section having a shape which is more divergent near the outlet of the inlet flow section and less divergent near the exit of the nozzle.