Liquid ring pumps are used to pump a variety of fluid types. Corrosive fluids are easily handled by the work fluid but can cause corrosion of pumping mechanisms. The present invention provides a magnetically driven liquid ring pump with corrosion resistant pumping mechanisms which achieves a longer time between service intervals.

A fan arrangement includes a fan and toothed ring, and a converter motor includes a fan arrangement. The fan includes a base body on which fan blades are premolded, and the fan includes an annular region, which is premolded on the side of the fan blades facing away from the base body. The toothed ring is situated within the annular region, and thus, in particular, is set apart from the base body, and thus, in particular, is set apart from the base body via the fan blades.

A positive displacement device that converts energy, namely positive displacement compressors that rotate in a single rotational direction to displace working fluid contained in operating chambers. The device described herein is particularity advantageous for the ability to achieve high compression ratios in combination with high discharge pressure and high volumetric throughput in a single stage.

An element for compressing a gas to be compressed at a low temperature of ?40? C. or lower, which element (1) is provided with a housing (2) containing at least one rotor (3) that is rotatably arranged with respect to the housing (2) and having an inlet (6) for the gas to be compressed and an outlet (7) for compressed gas, characterized in that the element (1) is configured for compressing the gas to be compressed having the low temperature by providing the element (1) with a heating duct (8) that runs through the housing (2), the heating duct (8) being provided with an inlet (9) where a first heat medium is introduced into the housing (2) at a higher temperature than the aforementioned low temperature and an outlet (10) where the first heat medium is evacuated from the housing (2).

An element for compressing a gas to be compressed at a low temperature of ?40? C. or lower, which element (1) is provided with a housing (2) containing at least one rotor (3) that is rotatably arranged with respect to the housing (2) and having an inlet (6) for the gas to be compressed and an outlet (7) for compressed gas, characterized in that the element (1) is configured for compressing the gas to be compressed having the low temperature by providing the element (1) with a heating duct (8) that runs through the housing (2), the heating duct (8) being provided with an inlet (9) where a first heat medium is introduced into the housing (2) at a higher temperature than the aforementioned low temperature and an outlet (10) where the first heat medium is evacuated from the housing (2).

An attachment structure is for attaching a compressor to an attachment surface of an attachment target member. The compressor is a scroll type compressor and has a housing, a fixed scroll and a movable scroll. The housing is fixed to the attachment surface. The fixed scroll is fixed inside the housing and has a fixed-side tooth having a scroll shape. The movable scroll has a movable-side tooth having a scroll shape and engaging with the fixed-side tooth. The movable scroll revolves with respect to the fixed scroll. A central axis around which the movable scroll revolves is parallel with the attachment surface. A vibration direction, which is included in a radial direction of the compressor and in which a vibration component becomes largest, is different from a normal direction when viewed in an axial direction of the central axis.

An attachment structure is for attaching a compressor to an attachment surface of an attachment target member. The compressor is a scroll type compressor and has a housing, a fixed scroll and a movable scroll. The housing is fixed to the attachment surface. The fixed scroll is fixed inside the housing and has a fixed-side tooth having a scroll shape. The movable scroll has a movable-side tooth having a scroll shape and engaging with the fixed-side tooth. The movable scroll revolves with respect to the fixed scroll. A central axis around which the movable scroll revolves is parallel with the attachment surface. A vibration direction, which is included in a radial direction of the compressor and in which a vibration component becomes largest, is different from a normal direction when viewed in an axial direction of the central axis.

A method for controlling the rotational speed (S) of an electric motor driven air compressor (2) that supplies compressed air to a pneumatically operated system (5) of a vehicle (1), characterized by the preliminary steps of: a) determining the efficiency (e) of the air compressor (2) for different values (Si) of the rotational speed (S) of the air compressor (2), the efficiency (e) of the air compressor (2) corresponding to the ratio between the pneumatic power (PI) produced by the air compressor (2) and the power (PO) given to the air compressor (2); b) determining one or several specific values (S2, S4) among said different values (Si), for which the efficiency (e) of the air compressor (2) is higher than a threshold value (emin) and/or comparatively higher than those determined for values (SI, S3) close to said specific value(s) (S2, S4); the preliminary steps a) and b) being preferably implemented only once; and characterized by the further repetitive steps of: c) determining the air consumption rate of the pneumatically operated system (5) receiving compressed air from the air compressor (2); d) determining a minimum rotational speed (Smin) of the air compressor (2) to obtain an air production rate of the air compressor (2) that is equal or substantially equal to said determined air consumption rate; e) determining if the specific value or one of the specific values (S2, S4) is greater than said determined minimum rotational speed (Smin); f) if no specific value is greater than said determined minimum rotational speed (Smin), controlling the rotational speed (S) of the air compressor (2) based on said minimum rotational speed (Smin); g) if only one specific value (S4) is greater than said determined minimum rotational speed (Smin), controlling the rotational speed (S) of the air compressor (2) based on said only one specific value (S4); h) if a plurality of specific values (S2, S4) is greater than said determined minimum rotational speed (Smin), determining the specific value (S2) with the best efficiency among said plurality of specific values (S2, S4) and controlling the rotational speed (S) of the air compressor (2) based on said specific value (S2) with the best efficiency.

A method for controlling the rotational speed (S) of an electric motor driven air compressor (2) that supplies compressed air to a pneumatically operated system (5) of a vehicle (1), characterized by the preliminary steps of: a) determining the efficiency (e) of the air compressor (2) for different values (Si) of the rotational speed (S) of the air compressor (2), the efficiency (e) of the air compressor (2) corresponding to the ratio between the pneumatic power (PI) produced by the air compressor (2) and the power (PO) given to the air compressor (2); b) determining one or several specific values (S2, S4) among said different values (Si), for which the efficiency (e) of the air compressor (2) is higher than a threshold value (emin) and/or comparatively higher than those determined for values (SI, S3) close to said specific value(s) (S2, S4); the preliminary steps a) and b) being preferably implemented only once; and characterized by the further repetitive steps of: c) determining the air consumption rate of the pneumatically operated system (5) receiving compressed air from the air compressor (2); d) determining a minimum rotational speed (Smin) of the air compressor (2) to obtain an air production rate of the air compressor (2) that is equal or substantially equal to said determined air consumption rate; e) determining if the specific value or one of the specific values (S2, S4) is greater than said determined minimum rotational speed (Smin); f) if no specific value is greater than said determined minimum rotational speed (Smin), controlling the rotational speed (S) of the air compressor (2) based on said minimum rotational speed (Smin); g) if only one specific value (S4) is greater than said determined minimum rotational speed (Smin), controlling the rotational speed (S) of the air compressor (2) based on said only one specific value (S4); h) if a plurality of specific values (S2, S4) is greater than said determined minimum rotational speed (Smin), determining the specific value (S2) with the best efficiency among said plurality of specific values (S2, S4) and controlling the rotational speed (S) of the air compressor (2) based on said specific value (S2) with the best efficiency.

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.