Hitachi, Ltd.

Yoshiaki Abe

Haruo Miura

Koji Nakagawa

Haruki Sakai

Takeo Takagi

Yasuo Fukushima

Minoru Hiroshima

Naohiko Takahashi

Osami Matsushita

Takashi Nagaoka

Toshio Kaneko

Junichi Kaneko

Mitsuho Yoneyama

Tadashi Kaneki

Hiroshi Ohmachi

Souji Sakata

Naofumi Sakanashi

A controller of magnetic bearing controls the rotor speed with a reduced drive current while suppressing the rotor vibration. The controller implements the ABS control, N-cross control, N-straight control and FF control in proper combination in addition to the basic PID control. A computer in the controller determines the activation of each control in accordance with a predetermined table of control plan in response to the detected rotor speed.

Method and apparatus for controlling a magnetic bearing

A centrifugal compressor has diffusers which convert a high velocity, low pressure stream of fluid which flows out of an impeller to a high-velocity high-pressure flow due to the action of a purality of stator blades disposed near the outer periphery of the impeller. In this compressor, the portion of the stator blade or of an auxiliary blade which is provided in the diffuser located on the side of a front shroud is disposed closer to the impeller than the portion thereof located on the side of a main shroud, and the leading edge of the stator blade is thus inclined from the portion thereof located on the side of the main shroud to the portion thereof located on the side of the front shroud. The configuration of the front edge of a stator blade or of an auxiliary blade which is provided in the diffuser is so improved as to restrict back flow which occurs on the side of the front shroud when the flow rate is small and to lower the minimum flow rate. Furthermore, an auxiliary blade and an intermediate blade are disposed between the adjacent stator blades, and the leading edge of the auxiliary blade is so improved as to enlarge the operation range of the diffuser and to improve volume control greatly.

Centrifugal compressor

In a diffuser for a centrifugal compressor of the type which includes an impeller rotatably provide on a downstream side of the suction casing and a plurality of radial stator blades arranged tangentially with respect to the impeller, auxiliary blades are provided between the impeller and the stator blades, with the auxiliary blades having a chord length shorter than that of the stator blades and being slidable in the axial direction of the impeller. Further, the auxiliary blades are connected to devices designed to move them in the axial direction.

Diffuser for a centrifugal compressor

A diffuser centrifugal compressor of a comprising a plurality of stator blades provided outside an impeller thereof, and which converts kinetic energy of fluid from the impeller into pressure energy by operation of the stator blade. The diffuser is provided with sub-blades near the inner ends of the stator blades, and intermediate blades near outer ends of and between the stator blades.

Diffuser for centrifugal compressor

The invention relates to a capacity control method for controlling the capacity of a multistage compressor in response to a flow rate signal by varying the openings of vanes at individual stages. The relationships of the openings of the vanes of the individual stages are made to vary in response to the flow rate signal from the multistage compressor. Thus, when the flow rate of the multistage compressor is far from the anti-surge capacity within the operable range thereof, it is possible to select vane opening relationships which provide the highest efficiency for the multistage compressor. When the flow rate of the multistage compressor drops to either a value near the anti-surge capacity or the inoperable range, on the other hand, it is possible to select vane opening relationships which provide an enlargement of the operating range of the multistage compressor, before the flow rate enters that inoperable range.

Method of capacity controlling of multistage compressor and apparatus

A device for changing and attaching or mounting an angle of stationary vanes of an axial-flow fluid machine by rotating the stationary vanes through a circumferential movement of an intermediate cylinder. The device includes at least one arm secured to one end of the intermediate cylinder and engaging at a second end in a groove formed in a block member which is attached to an end of an actuator and is movable in a tangential direction of the intermediate cylinder. A guide arrangement is provided for guiding a movement of the block member and at least a portion of the actuator so as to ensure a smooth operation of the actuator by freeing the same from any influence of undesireable forces such as lateral pressure caused by a thermal expansion of the intermediate cylinder.

Vane angle changing device for an axial fluid machine

A rotor of an axial-flow machine including a plurality of spacer members arranged peripherally of the rotor for providing a channel on the surface of the rotor. The spacer members are located in a manner to straddle the forward stage disc section and the rearward stage disc section, to enable each rotor blade to be replaced individually with a new one by mounting and removing the rotor blade axially of the rotor. The rotor of the axial-flow machine has improved reliability and flow performance.

Growing community of inventors

Ibaraki, Japan

Yoshiaki Abe