Hitachi, Ltd.

Hitachi Cable, Inc.

Other

Hisao Sonobe

Shigeru Oho

Hiroshi Kajioka

Tatsuya Kumagai

Junichi Makino

Sadayuki Okada

Munehiro Akiyama

Masahiro Matsumoto

Atsushi Kanke

Masamichi Yamada

Akihiko Emori

Izumi Watanabe

Keiichi Nakada

Kaoru Uchiyama

Yasuhiro Gunji

Takuya Kinoshita

Masato Isogai

Masahiro Komachiya

Shizuhisa Watanabe

Kouji Kitano

Hideo Tsukioka

Hiroshi Araki

Tatsunori Sakaguchi

Moriichi Sato

Yasushi Okada

Etsuo Oe

Tomoaki Mino

Keiji Abe

Osamu Kobayashi

Disclosed herein is an angular velocity measuring device including: first and second oscillators elastically supported on a substrate; an elastic connecting beam elastically connecting the first and the second oscillator; and an oscillating means for oscillating the first and the second oscillator for differential oscillation, wherein a viscous force generating means for suppressing in-phase oscillation of the first and the second oscillator is incorporated into the elastic connecting beam.

Angular velocity measuring device

A hot-wire type air flow meter for an internal combustion engine has an exothermic resistor film provided on a thin portion formed on a silicon substrate and a control circuit for controlling a voltage to be applied to the resistor film or a current to be supplied. The resistor film is arranged in a suction pipe of the internal combustion engine and heat is emitted to an air through the resistor film. In the case where a liquid droplet is deposited onto the resistor film, the control circuit controls the applied voltage to a value smaller than a voltage which is applied to the resistor film at the time of measuring a maximum specified measuring range or controls the supply current to a value smaller than a current flowing in the resistor film at the time of measuring the maximum specified measuring range.

Hot-wire type air flow meter for internal combustion engine

An electric power system comprises a plurality of capacitors connected in series, a plurality of DC-AC conversion circuits converting each DC voltage of the plurality of capacitor to an AC signal that an AC component equivalent to the inter-terminal DC voltage of each of the capacitors is superimposed on the respective DC voltages and a plurality of condenser couplers break the respective DC voltages and output the AC components respectively, and a processing circuit detecting the inter-terminal DC voltage of the corresponding capacitor from the AC component.

Electric power system having series connected capacitor

An on-vehicle fiber-optic cylinder pressure sensor capable of detecting the pressure within a combustion chamber with precision has an optical fiber capable of converting a change in the pressure within a combustion chamber received on its outer surface on an engine gasket into a change in the light quantity passing therethrough. A light emitting device for emitting the passed-through light; a photosenses or senses the passed-through light of which the light quantity has been changed. A converter converts the light quantity of the passed-through light into an electric signal. A reference pressure setting apparatus sets a reference electric signal. A signal processor includes an apparatus for watching a corresponding reference electric signal to the reference electric signal included in the detected electric signal.

Fiber-optic cylinder pressure sensor

A phase modulated light is propagated through an optical fiber sensing loop, from which a propagated light is obtained. The propagated light is converted to an electric signal, from which a fundamental wave component and even number harmonic wave components of a phase modulating signal for the phase modulated signal are detected. In accordance with the changes of the fundamental and even number harmonic wave components, fault is detected. On the other hand, the electric signal may be integrated to provide an integrated signal. In accordance with the comparison between the integrated signal and a fault reference voltage, the fault may be detected.

Method for detecting fault of optical fiber gyro and apparatus for

The invention provides an apparatus for measuring intake air for an internal combustion engine by means of a detecting unit including a heat generating resistor, and a flow amount arithmetic unit for calculating an air flow amount on the basis of the output from the detecting unit. The measuring apparatus further includes an equalizer circuit for regulating the amplitude or phase of the output signal from the detecting unit, between the detecting unit and the flow amount arithmetic unit.

Intake air amount measuring apparatus for internal combustion engines

A photodetector generates an electric signal by receiving a light signal which is obtained by coupling lights having propagated through an optical fiber sensing loop in clock-wise and counter clock-wise directions, and modulated in a phase modulator. The electric signal is detected in a synchronous detection circuit to generate a fundamental wave component of the phase modulation signal, a duplicate harmonic wave component, a quadruple harmonic wave component, and an orthogonal component which is obtained in accordance with a phase shift of the quadruple harmonic wave component by one quarter period.

Phase adjustable optical fiber gyro using both even order harmonics and

A signal processing circuit of an optical fiber gyro comprises a memory for storing data measured in the signal processing circuit in accordance with angular velocities applied to an optical fiber sensing loop at preparatory stage, and the applied angular velocities. In operation, the memory is accessed in accordance with data obtained in the signal processing circuit at an operation stage, so that an angular velocity is read from the memory without complicated calculation.

Optical fiber gyro with memory storing data measured under application

The light emitted from a laser diode is divided into two lights and the divided lights are introduced into a sensing loop such that the lights propagate through the sensing loop clockwise and counterclockwise. These lights are combined by a light receiving device and then a signal processing circuit calculates an angular velocity .OMEGA.'. The temperature near the laser diode is detected to obtain a correction value Kt, a current supplied to the laser diode is detected to obtain a correction value Ki and a corrected angular velocity .OMEGA. is obtained by calculating the product of the angular velocity with the correction values Ki and Kt, i.e., .OMEGA.=.OMEGA.'*Ki*Kt.

Fiber-optic gyroscope having angular velocity correction

An interference sensor passes radiation from a source and a polariser to a loop of optical fiber so that radiation beams circulate in opposite directions around the loop and interfere. The loop contains an optical phase modulator which imposes an optical modulator on the radiation beams circulating on the loop. A converter detects the interfering and modulated beams and generates an interference signal which is then processed by an analyser. The interference in the loop is dependent on rotation of the loop and therefore analysis of the interference signal permits that rotation to be measured. In the present invention, the interference signal is (i) sampled at a frequency different from that of the optical modulation, or (ii) electronically modulated in the analyser at a frequency different from that of the optical modulation, or (iii) optically modulated in the loop at a second optical modulation frequency. The analysis in the analyser may be in the frequency domain (i.e. consideration being given to the frequency of the interference signal) or in the time domain (i.e. independent of frequency).

Interference sensor and method utilizing extracted alliasing frequency

In an optical fiber gyroscope, the sensitivity thereof is optimized with a phase bias afforded by utilizing the phase characteristics of an optical branching/coupling unit. Further, the fluctuation of the intensity of a light source and the error and secular change of the phase characteristics of the optical branching/coupling unit are compensated by an electronic circuit. Moreover, an optical fiber loop is located in a heat insulation casing so as not to be affected by an ambient temperature change, thereby to prevent the drift of the optical fiber gyroscope attributed to an temperature change. Thus, the optical fiber gyroscope of high measurement accuracy is provided.

An improved optical branching/coupling unit for an optical fiber

An interface signal produces in a phase modulation type fiber optic gyroscope is classified into odd and even groups at a synchronous detector. An angular velocity is processed by the signals of even groups and odd groups.

Phase modulation type fiber optic gyroscope

A constant pressure boiling cooling system including evaporators, a condenser and a liquid refrigerant sump, wherein the evaporators and the condenser are arranged substantially horizontally in side-by-side relation, and the first communicating tubes connect the upper portions of the evaporators to the upper portions of the condenser respectively, and the second communicating tubes connect the lower portions of the evaporators to the lower portions of the condenser respectively.

Constant pressure type boiling cooling system

A constant pressure type ebullient cooling equipment has a liquid receiver at a position higher than a condenser. The liquid receiver is connected with a vaporizer containing a liquid refrigerant by a coupling pipe. A valve and a device for opening or shutting the valve are disposed at an upper part of the liquid receiver. When refrigerant vapor produced in the vaporizer is introduced into the condenser, refrigerant liquid in the vaporizer moves to the liquid receiver. The condenser and the liquid receiver are connected by a deaerating pipe. Non-condensable gases such as air contained in the cooling equipment and the refrigerant enter the liquid receiver, and are emitted through the valve. As a result, the interior of the cooling equipment is held under a substantially constant pressure.

Constant pressure type ebullient cooling equipment

An apparatus for cooling a heat generating member by utilizing the latent heat of vaporization of a boiling refrigerant, having a cooling vessel including an evaporator section containing the boiling refrigerant and adapted to transmit the heat generated by the heat generating member to the refrigerant, and a condenser section for liquefying the gasified refrigerant; a liquid refrigerant reservoir open at its upper end and adapted to store a body of the refrigerant which does not directly take part in a cooling operation while the cooling operation is being performed; and a communication means for communicating the cooling vessel with the liquid refrigerant reservoir, the cooling vessel and the communication means being filled with the boiling refrigerant.

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Hitachinaka, Japan

Hisao Sonobe