Hitachi, Ltd.

Hitachi Car Engineering Co., Ltd.

Other

Hitachi Automotive Systems, Ltd.

Keiichi Nakada

Izumi Watanabe

Masamichi Yamada

Junichi Horie

Kei Ueyama

Hiroshi Nakano

Masahiro Matsumoto

Shinya Igarashi

Keiji Hanzawa

Hiromu Kikawa

Atsushi Kanke

Naoki Saito

Masayuki Kozawa

Hiroshi Yoneda

Rintarou Minamitani

Kazunori Suzuki

Ryo Sato

Hiroshi Hirayama

Hisao Sonobe

Yasuhiro Kanamaru

Jiro Taniguchi

Kei Ueda

Yasuhiro Asano

A connection terminal is on a flange of a thermal flow meter. A terminal connection part has a first and a second bent part. The first bent part is bent from a first direction to a second direction. The second bent part has is bent from the first bent part to a third direction. The first and second bent parts are formed such that when connection pin parts of a plurality of the connection terminals and terminal connection parts of the plurality of connection terminals are projected onto a first imaginary plane, an imaginary line L extending along a first direction passing through the projection areas of each of the terminal connection parts of the plurality of connection terminals passes between the projection areas of the connection pin parts from among the connection pin parts of the plurality of connection terminals, that are positioned on both sides.

Thermal flow meter

A gas flow rate measuring apparatus including a gas flow rate detection circuit configured to output a first analog signal of a gas flow rate of a gas; a gas temperature detection element configured to output a second analog signal of a temperature of the gas or a temperature of an integrated circuit; analog-to-digital converters for converting the analog signals into respective digital signals; a digital signal correction device comprising a map table and configured to correct a characteristic bend of the first digital signal based on the map table and the second digital signal, wherein the map table comprises correction constants arranged as lattice points, wherein a first number of lattice points in a first region of the characteristic bend of the gas flow rate signal is larger than a second number of lattice points of a second region outside the first region of the characteristic bend.

Gas flow rate measuring apparatus for minimizing temperature dependent errors

A thermal type flow rate measuring device can certainly prevent adhesion of water droplet onto a sensor element and thus achieve high reliability. The thermal type flow rate measuring device includes an auxiliary passage defined within a main passage for introducing a part of fluid flowing through the main passage, a sensor disposed within the auxiliary passage for detecting flow rate of the fluid and capturing means formed on an inner periphery of the auxiliary passage for capturing liquid contained in the fluid and transferring the captured liquid.

Thermal flow rate measuring device

Conventional thermal flow measurement devices lack consideration for automobiles in severe environments. A detection element of the thermal flow measurement device according to the present invention is structured by the provision of a planar substrate made of a material having good thermal conductivity, such as silicon or ceramic, with a thin-walled portion (diaphragm). On the surface of the thin-walled portion, the detection element comprises a heat element as a heater heated to a temperature being different to a predetermined extent from the temperature of the air flow to be measured, temperature-detecting resistors as temperature-detecting means on both sides of the heat element, wiring portions formed of electrical conductors that draw signal lines from the heat element and the temperature-detecting resistors and that have a melting point of 2000&#xb0; C. or higher, and pads.

Reduced resistance thermal flow measurement device

A flow rate sensor has a problem that a resistance value of a heat generating resistor itself varies and sensor characteristics are changed during use of the sensor for a long term. Also, the temperature of the heat generating resistor must be adjusted on a circuit substrate with a resistance constituting one side of a fixed temperature difference control circuit, and this has been one of factors pushing up the production cost. All resistances used for fixed temperature difference control are formed on the same substrate as temperature sensitive resistors of the same material. This enables all the resistances for the fixed temperature difference control to be exposed to the same environmental conditions. Hence, even when the resistances change over time, the changes over time occur substantially at the same tendency. Since the resistances for the fixed temperature difference control change over time essentially at the same rate, a resulting output error is very small.

Thermal type flow rate measuring apparatus

A thermal air flowmeter having excellent temperature characteristics and improved measurement accuracy. The thermal air flowmeter includes a temperature sensor disposed in a casing of the air flowmeter, a computing unit for correcting a flow rate detection voltage from a measuring element by using the temperature sensor, and a heating temperature control disposed in a temperature control circuit for performing temperature control of a heating resistor to vary a temperature rise of the heating resistor relative to an air temperature depending on the air temperature. Flow rate detection errors of the thermal air flowmeter caused by an overall temperature change and a temperature change on an intake passage wall surface can be corrected simultaneously and a thermal air flowmeter having superior measurement accuracy can be realized.

Thermal flowmeter for measuring a flow rate of fluid

A thermal-type fluid flow sensor comprises a heating resistor formed on a thin film of a substrate, and plural thermal sensitive resistors configuring a bridge circuit. The thermal sensitive resistors are disposed on the thin film of the substrate so as to be located on an adjacent upstream side and an adjacent downstream side of the heating resistor in a stream direction of fluid to be measured. Resistor traces for the thermal sensitive resistors are formed so that the respective thermal sensitive resistors exhibit substantially equal changes in resistance with each other to distortion caused in the thin film.

Fluid flow sensor and fluid flow measurement device

The present invention provides an air flow measuring device comprising a housing with a sub-passage having a inlet and a outlet for air flow formed in the housing, the sub-passage further having a predefined curvature with a maximum downstream point and a flow measuring element located in the sub-passage at a position at least further downstream from the point.

Air flow measuring device provided with a vent in air passage

A highly accurate physical quantity sensor which can ensure reliability in strength and reduce resistance changes caused by stresses. Assuming, with respect to stress &#x3c3; imposed on a substrate in a predetermined direction (e.g., direction in which maximum stress is imposed), a parallel direction to be a horizontal direction and a perpendicular direction to be a vertical direction, each of resistors of the sensor has a horizontal resistance component Rl and a vertical resistance component Rt. When a ratio of a piezoresistance coefficient &#x3c0;l of the horizontal resistance component Rl, which is provided when the stress imposed on the substrate is applied to the horizontal resistance component Rl, to a piezoresistance coefficient &#x3c0;t of the vertical resistance component Rt, which is provided when the stress is applied to the vertical resistance component Rt, is &#x3c0;l:&#x3c0;t=&#x2212;n:1 (n:integer), a resistance value ratio of the vertical resistance component Rt to the horizontal resistance component Rl is set substantially equal to the ratio of the piezoresistance coefficient &#x3c0;l to &#x3c0;t.

Physical quantity sensor

A thermal type flow measuring apparatus includes a heating resistor provided in a thin part of a substrate and a bridge circuit for driving the heating resistor to have a preset heating temperature, wherein resistor elements on sides forming the bridge circuit are temperature sensitive resistors, a part or whole of at least one of the temperature sensitive resistors is placed in the thin part and near the heating resistor so that the temperature sensitive resistor is influenced by a heat of the heating resistor, and the preset heating temperature is increased as the flow of fluid is increased. This configuration introduces flow dependency into the heating temperature of the heating resistor.

Thermal type flow measuring apparatus

A low-cost thermal flow meter that has good temperature characteristics and little variations. The thermal flow meter includes a sensor element including a heat-generating resistor and at least two temperature-measuring resistors disposed downstream and upstream. The sensor element is positioned in the flow of a measured medium. It also includes an adjusting means for adjusting a excess temperature (&#x394;Th=Th&#x2212;Ta) of the heat-generating resistor, which is the difference between the temperature (Ta) of the measured medium and the temperature (Th) of the heat-generating resistor. The adjusting means adjusts the excess temperature (&#x394;Th) of the heat-generating resistor depending on the temperature of the measured medium such that the excess temperature becomes smaller as the temperature of the measured medium increases.

Thermal fluid flow meter having heat-generating resistor and temperature adjuster therefor

IN a thermal type flow measurement apparatus, a heating element is disposed in a fluid passage and generates heat by a passage of a current through itself. A first thermal sensitive element is disposed adjacent upstream of the heating element in a direction of fluid flow to be measured. A second thermal sensitive element is disposed adjacent downstream of the heating element in the direction of fluid flow to be measured. The fluid passage is provided with the heating element, the first thermal sensitive element, and the second thermal sensitive element. The fluid passage has an asymmetric structure with respect to the direction of fluid flow. Means for measuring a difference of temperatures is sensed by the first and the second thermal sensitive elements to produce a voltage according to a fluid flow rate. Heat control means for controlling the passage of the current through the heating element so that a sum with weights of respective temperatures sensed by the first and the second thermal sensitive elements reaches a preset value.

Thermal type flow measurement apparatus having asymmetrical passage for flow rate measurement

A Thermal type fluid flow sensor comprises a heating resistor formed on a thin film of a substrate, and plural thermal sensitive resistors configuring a bridge circuit. The thermal sensitive resistors are disposed on the thin film of the substrate so as to be located on an adjacent upstream side and an adjacent downstream side of the heating resistor in a stream direction of fluid to be measured. Resistor traces for the thermal sensitive resistors are formed so that the respective thermal sensitive resistors exhibit substantially equal changes in resistance with each other to distortion caused in the thin film.

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Hitachinaka, Japan

Keiichi Nakada