Abstract: A mechanism for differential pressure sealing for use in a compressor, such as for fuel cell applications, is described. In a dual-stage compressor, a low pressure side and/or a high pressure side of the dual-stage compressor may include a compressor wheel supported by a shaft that can rotate about an axis of the shaft. A seal carrier may be provided that rotates with the compressor wheel and includes a groove for receiving a sealing ring, which may be a split expansion ring. A static seal plate may be positioned around a periphery of a portion of the seal carrier, such that the sealing ring can seal against a contact surface of the static seal plate when received in the groove in order to create a pressure differential seal. The low pressure side may include one sealing ring, whereas the high pressure side may include two sealing rings positioned in series.

Abstract: A butterfly bypass valve includes a housing defining a bypass flow passage with a pivotable throttle plate therein. An outer edge of the throttle plate in a closed position is in sealing engagement with a sealing portion of the housing such that the throttle plate restricts fluid flow through the bypass flow passage. The throttle plate is pivotable to an open position to allow fluid flow through the bypass flow passage. A port in the housing allows a portion of fluid passing through the bypass flow passage to be removed when the throttle plate is pivoted to the open position. A predetermined amount of pivoting of the throttle plate toward the open position can occur so as to allow flow through the port, while maintaining the edge of the throttle plate in substantially sealing engagement with the sealing portion so as to substantially prevent flow through the bypass passage.

Abstract: A flow-control assembly may include a fluid conduit and a flow-control valve in the fluid conduit. The flow-control assembly may further include a fluid expansion conduit with an inlet defined at least in part by the fluid conduit and configured to selectively receive flow of a fluid from the fluid conduit. The fluid expansion conduit may further include an outlet in fluid communication with the fluid conduit downstream of the flow-control valve. A rotating fluid expander in the fluid expansion conduit may be configured to expand the fluid and thereby rotate and in some embodiments generate electricity. In a first position flow is substantially blocked. In a second position flow is allowed through the fluid expansion conduit. In a third position flow through the fluid conduit is allowed without necessarily passing through the fluid expansion conduit.