Nec Corporation

Mayekawa Mfg. Co., Ltd.

Tdk Corporation

Tokyo Magnetic Printing Co., Ltd.

Toshiro Hattori

Kiyoshi Tanaka

Katsuyuki Takahashi

Hiroshi Kajitani

Masatomo Mizuta

Yoshiho Yanagita

Yoshiyuki Kobayashi

Akira Matsui

Harumi Sato

Fumihiko Kaneko

Norimichi Kawashima

Kazue Yamada

Yujiro Shinoda

A screw compressor is equipped with a manually operated internal volume ratio adjusting slide valve and capacity adjusting slide valve. The compressor is simple in construction, can be produced with low cost, can accommodate decrease in suction pressure, for example, in an aged gas well, and can be operated without an electric power source for controlling the operation thereof. Also a combined screw compressor unit consisting of a plurality of screw compressors for producing high discharge pressure is provided which can accommodate high suction pressure in order not to overload the higher pressure compressor or compressors with the efficiency of the unit kept as high as possible by including at least a screw compressor according to the present invention in the unit.

Screw compressor capable of manually adjusting both internal volume ratio and capacity and combined screw compressor unit accommodating variation in suction or discharge pressure

A multi-stage screw compressor unit and method of operation thereof are provided, which enable operation with high efficiency always even when suction or discharge pressure fluctuates widely, the compressor unit comprising a combination of a compression stage provided with an unloader slide valve and that provided with an internal volume ratio control valve, or a combination of compression stage provided with an internal volume control valve and that of fixed internal volume ratio, or a combination of compression stages each provided with an internal volume control valve.

Multi-stage screw compressor unit accommodating high suction pressure and pressure fluctuations and method of operation thereof

The invention provides a method of operating a screw compressor equipment without reducing the efficiency, in which a screw compressor of which the internal volume ratio is variable by means of an internal volume ratio control valve is driven by a driving machine the discharge side of the compressor is communicated with the suction side of the same by way of a bypass control valve as needed, the internal volume ratio control valve is always controlled to be located at a position calculated so that the internal volume ratio with which the polytropic efficiency is maximum is obtained, and gas flow rate is controlled by controlling the rotation speed under normal conditions and controlled by controlling the bypassing flow rate from the discharge side to the suction side under very low rotation speed.

Screw compressor equipment for accommodating low compression ratio and pressure variation and the operation method thereof

The operating system of a gas engine accommodating to sour gas comprises a sour gas compressing and feeding part including a compressor and a gas engine , a pre-membrane-treatment for obtaining a compressed gas of proper temperature removed of oil, solid mixture, etc. from the high pressure, high temperature sour gas discharged from the compressor, a preceding step filter for removing a minute amount of oil and water contained in the branched off gas of the compressed gas of proper temperature , a membrane separator for separating the gas from the filter into sweet gas and the hydrogen sulfide gas, and an adsorptive separator through which sweet gas is obtained only at the time of starting of the compressor

Operating method of gas engine accommodating to sour gas and the system thereof

A positioning control device is provided which is capable of avoiding the limit cycle in which the head moves back and forth between two dead zones on both sizes of the center of the target track. When a magnetic head is in the dead zone and the head position is separated from the center of the target track, the center position of the dead zone is set as the head position.

Positioning control device, changeable magnetic disc device, and head control method

A positioning control system for a disk drive can reduce static friction of the sliding type actuator to be a cause of degradation of low order spindle rotation synchronization run-out. The positioning control system includes position error detecting means for detecting a position error between a center of a data track on a disk medium and a head for reading data from the disk medium, shifting means for shifting the head, a phase compensator for positioning the head at a target position on the basis of a result of detection of the position error detecting means, detecting means for detecting influence of a static frictional force for the shifting means based on an output of the phase compensator, a friction compensator outputting a feed forward signal for driving the shifting means, and means for applying the feed forward signal from the friction compensator to the shifting means from the friction compensator when influence of the static frictional force to the shifting means is detected by the detecting means.

Head positioning control system for disk drive

The frequency rectification filter, in principle, measures an amplitude and phase of a particular frequency and compresses the frequency. Accordingly, if no initial value is present, it is necessary to take a time more than one turning cycle. Consequently, no effect can be seen immediately after the rise of an apparatus, and head positioning takes much time. The object of the present invention is to reduce this time. According to the present invention, a state amount of the frequency rectification filter is stored in memory before unloading the head from the disc, so that at apparatus rise, the spindle rotation angle is matched so as to operate the filter, thus increasing the speed of the rise of the effect of the frequency rectification filter. Thus, the risa of the frequency entire apparatus can be performed rapidly.

Medium replacement type disc apparatus

In a head positioning mechanism has a micro tracking actuator which is between a carriage and a supporting spring for making the supporting spring be rotated relative to the carriage to adjust a position of a magnetic head, the micro tracking actuator has a pair of coils held to one of said carriage and said supporting spring. Each of the coils generates magnetic flux in response to a flow of electric current therein. The micro tracking actuator further has a magnet arrangement held to another of the carriage and the supporting spring to face the coil means in a predetermined direction. The magnet arrangement traverses the magnetic flux to have a particular size which varies in accordance with a predetermined relation in response to a relative movement between the coils and the magnet arrangement. The carriage is movably mounted to a magnetic disk device to which the head positioning mechanism applied. The supporting spring is attached to the carriage and rotatable around a predetermined axis extending in the predetermined direction. The supporting spring holds the magnetic head to perform a seeking operation of the magnetic head in cooperation with the carriage.

Head positioning mechanism for magnetic disk device provided with micro tracking actuator using magnetic force drive control method therefor

To provide head-positioning system which can control tracking movement of the magnetic head reliably and smoothly with a high speed, enlarging the controllable frequency band of a fine tracking actuator by suppressing interference between the fine tracking actuator and a main actuator (,), a head-position control circuit of the head-positioning system comprises: a phase compensating controller (,) for obtaining deviation information of the read/write head relative to a designated position from the positional information (S,) detected by the read/write head, and generating a positioning correcting signal (S,) for feedback-controlling the fine tracking actuator to drive the slider supporting spring (,) with a torque value to make the read/write head follow the designated position, according to the deviation information (S,); and a vibration suppressing controller (,) for forward-controlling the main actuator to maintain an angular position of carriages (,) to be fixed by controlling the main actuator (,) to generate the same torque value with the torque value to be generated by the fine tracking actuator, referring to the positioning correcting signal (S,).

Head-positioning system with an improved fine tracking actuator control scheme

The object of the present invention is to provide a compression system to effectively compress contaminated gas containing water and other corrosive substances (natural gas) without suffering any adverse effects caused by toxic substances, including impurities, and which includes a path which heats the compressor using gas with a low dew-point temperature, such as water free gas or purified gas from outside the system, that is substantially free of water, or discharged gas after having been compressed by the compressor, a separator provided upstream of the suction section of the compressor, which separates water and the like from natural gas by cooling and condensation, and a dew-point maintaining arrangement for maintaining the discharged temperature of gas from the compressor above the dew-point temperature of the compressed gas when compressing natural gas from which water has been separated by the separator and characterized in that, when direct compression of the actual gas (contaminated gas) is necessary, a heating operation is carried out by a gradually increasing the pressure of the gas discharged from the compressor by controlling the suction pressure of the compressor, by adjusting the opening of a pressure control valve on the return pipe, and after the heating operation, the actual compressing operation of natural gas is not affected, and a stable continuous operation is enabled due to a smooth switchover.

System for compressing contaminated gas

A head positioning mechanism for a magnetic disc device includes a support spring having one end portion that supports a magnetic head, and the other end portion at which a rotating shaft is disposed. A carriage has one end portion that pivotally supports the rotating shaft of the support spring, and another end portion that is connected to a rotary actuator, to position the magnetic head to a predetermined position on the magnetic disc in cooperation with the carriage and the support spring. A stopper is provided on the carriage, and restricts a rotatable range of the support spring on the carriage. A positioning control at a head precision seek is facilitated as a result.

Magnetic disc device with stopper on carriage to limit rotational

Head positioning mechanism for magnetic disk device provided with micro

A state variable estimator is operative, in a change-over of a magnetic head, to determine a predicted value of a state variable of a frequency-shaped filter in a follow-up to a track after the change-over based on a current head position of thereof before the change-over, by using a set of calculated coefficients representative of an amplitude and a phase difference relative to the current head position of a sine wave to be calculated by a discrete Fourrier series, as the sine wave represents the state variable of the frequency-shaped filter when the track is followed up, so that a state variable re-setting of control system is achieved to minimize a square error integration of the predicted value and a state variable of a phase compensating filter, as the change-over is a step response of a closed loop control system.

Tracking servo system for magnetic disc drive with reduced head-settling

A control system rotates disks as information storage media to position a head in a disk drive that records or reproduces data. An actuator swings the head in the radial direction of the disk. Positioning of the head is performed by a servo control system adjusting a drive current supplied to the actuator based on the value of the drive current and head position information. Parameters for the actuator are estimated based on the head position information and the value of the drive current obtained when the head is vibrated at one or more frequencies in a plurality of positions. The estimated parameters are used to adjust input/output signals for the servo control system to correct the preset parameters for the control system.

Control system for positioning head in disk device by estimating and

An abrasive tool comprises a base and an abrasive powder bonded to the base in the form of a single-layer structure in which the particles do not substantially overlap or rest one upon another. For the bonding purpose the abrasive powder is either dispersed in a dilute solution of a binder resin and a solvent for subsequent application of the solution to the base or is spread over and fixed to a binder resin coat formed beforehand on the base.

Growing community of inventors

Tokyo, Japan

Toshiro Hattori