Hitachi, Ltd.

Hitachi Car Engineering Co., Ltd.

Other

Kei Ueyama

Izumi Watanabe

Keiichi Nakada

Junichi Horie

Shinya Igarashi

Masamichi Yamada

Hiromu Kikawa

Masahiro Matsumoto

Keiji Hanzawa

Atsushi Kanke

Naoki Saito

Masayuki Kozawa

Hiroshi Yoneda

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

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

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

In a thermal-type airflow meter that measures an intake airflow rate in an internal combustion engine of an automobile or the like, there has been a problem that pulsation errors caused by external fluctuations under the environment including a large pulsation and reverse flow in the intake valve are difficult to be reduced. In order to solve this problem, the invention provides a flowmeter comprising a detection element that outputs a non-linear signal corresponding to a flow rate, and a regulation means that regulates an output signal of the detection element for controlling. With this construction, the regulation means executes output regulation processing that regulates irregularities of the detection element in the output signal, and inequality linearization processing that regulates an average value of the output signal after the output regulation processing by means of regulating parameters.

Flowmeter and flowmeter system

Air flow measuring device and engine having the air flow measuring device

Air flow measuring device

The present invention provides an air flow measuring device comprising a housing with a sub-passage having an inlet and an 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.

There is provided a flow rate measuring device which comprises a means for introducing a backward flow of the main passage into the sub-passage through the outlet of the sub-passage of the flow rate measuring device is provided near the outlet of the sub-passage, in order to keep the flow rate measuring element from being destroyed under the presence of dust and water in an intake manifold and which has high reliability for a long period of use and an excellent pulsation characteristic.

Flowrate measuring device with improved flow introduction into sub-passage outlet

A thermal type flow measuring device comprises a heating resistor(HF), a temperature measuring resistor(Ru) upstream of the heating resistor(HF) with respect to a fluid(Q), and a temperature measuring resistor(Rd) downstream of the heating resistor(HF). A heat sensitive resistance element(CF), the upstream temperature measuring resistor(Ru) and the downstream temperature measuring resistor(Rd) form a first bridge circuit, and this first bridge circuit and the heating resistor(HF) form a second bridge circuit. Feedback control means(OP, Tr) heat the heating resistor(HF) in accordance with an output for keeping a balance of the second bridge circuit. The distance between the heat sensitive resistance element(CF) and the heating resistor(HF) is larger than the distance between the upstream temperature measuring resistor(Ru) or the downstream temperature sensitive resistor(Rd) and the heating resistor(HF) so that the heat sensitive resistance element(CF) is positioned to receive less thermal influences from the heating resistor(HF) than the upstream temperature measuring resistor(Ru) and the downstream temperature sensitive resistor(Rd). The upstream temperature measuring resistor or the downstream temperature measuring resistor is heated by the heating resistor, and the flow rate of the fluid is measured based on an output for keeping a balance of the first bridge circuit.

Thermal type flow measuring 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.

Resin members, on the surfaces of which metal films are formed, are used for; an auxiliary air passage provided in a main air passage, in which a sensor element of a physical quantity sensor such as an air flow sensor, an intake-air temperature sensor, etc., is situated; a housing; and so forth; in order to decrease both the thermal conductivity and the emissivity of those components to respective small values, whereby the temperature increase of the sensor due to both the heat conduction and the heat radiation can be suppressed.

Growing community of inventors

Hitachinaka, Japan

Kei Ueyama