Mitsubishi Electric Corporation

Naoki Morinaga

Masahiro Kawai

Yuji Ariyoshi

Shinichiro Hidaka

Kazuhiko Otsuka

Naoyuki Kishikawa

A flow rate detector includes a detection circuit, which is configured to output as an analog signal a voltage in accordance with a flow rate of air flowing through an intake pipe, and a conversion circuit, which is configured to convert the analog signal input from the detection circuit to a digital signal based on an analog-to-digital conversion characteristic to output the digital signal. The analog signal that corresponds to a forward flow direction and is input to the conversion circuit is set to have a value larger than an input voltage range in which a missing code may occur in the analog-to-digital conversion characteristic.

Flow rate detector

This signal processing unit includes: a comparison signal output unit which outputs a comparison signal on a negative side that corresponds to a negative side portion, of a second amplitude-increased signal, which is on the negative side with respect to the comparison threshold TH; an averaging processing unit which outputs an average signal obtained by averaging the comparison signal; a coefficient multiplication processing unit which outputs a coefficient-multiplied signal obtained by multiplying the average signal by an adjustment coefficient set in advance; and a signal correction processing unit which outputs, as a flow rate signal, a value obtained by correcting a first amplitude-increased signal so as to be decreased by use of the coefficient-multiplied signal, wherein the comparison threshold TH is set on the basis of an output characteristic of a sensor measured in advance with respect to at least a forward flow direction of an intake air.

Thermal air flow meter with adjustment of pulsation correction function

There is provided a thermal-type airflow meter that reduces the number of output signals of the sensor circuit and that can suppress the accuracy of flow rate detection from being deteriorated because due to a nonlinear sensor output characteristic and a response delay in the output signal, the output signal shifts toward the positive side or the negative side. A thermal-type airflow meter outputs one or both of a positive-side comparison signal that is at the positive side of a comparison threshold value and a negative-side comparison signal that is at the negative side of the comparison threshold value, outputs a coefficient multiplication signal obtained by multiplying an average signal acquired by averaging the comparison signal by an adjustment coefficient, and outputs, as a flow rate signal, a value obtained by applying the coefficient multiplication signal to increase correction or decrease correction of the amplitude increase signal.

Thermal-type airflow meter

An environment sensor is mounted on a second surface of a circuit board that does not have a wire bonding pad, and is arranged in a measuring chamber that is disposed in a circuit board receiving portion. The measuring chamber has a communication port for communication with a main passage. According to this configuration, process addition attributable to integration between a flow rate measurement device and the environment sensor is not required. The environment sensor does not affect air flow in a bypass passage, and thus detection accuracy of a flow rate detection element that is arranged in the bypass passage does not decline.

Flow rate measurement device

A detection element portion is provided on an inner surface side of a plate as a wall surface portion defining a measurement passage in a flow measuring device. An intake-air temperature detection portion detecting a temperature of a fluid being measured is provided on one main surface of a substrate forming the detection element portion. A ventilation hole allowing a main passage in which the fluid being measured flows and the measurement passage to communicate is provided so as to penetrate through the plate. By achieving a state in which the substrate forming the detection element portion is installed so that an end thereof protrudes into the ventilation hole and a back surface of the end portion of the detection element portion where the intake-air temperature detection portion is formed is exposed toward the main passage, a response speed is enhanced.

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Tokyo, Japan

Naoki Morinaga