Mitsubishi Electric Corporation

Mitsubishi Denki Kabushiki Kaisha

Yuji Ariyoshi

Masahiro Kawai

Shinichiro Hidaka

Hiroyuki Uramachi

Koji Tanimoto

Naoyuki Kishikawa

Kazuhiko Ohtsuka

Kazuhiko Otsuka

Naoki Morinaga

Kazuto Akagi

Naruki Suetake

Takaaki Murakami

Tomoya Yamakawa

Hiroshi Sakanoue

Manabu Tsukamoto

Takahiro Ohnakado

Kouji Tanimoto

Yasuhiro Kosasayama

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

Provide a flow measuring device which inhibits a reduction of flow detection accuracy, which is caused by an influence of a bottom flow which is flowed and inputted from a fit gap between a flow detecting element and an installing portion of the flow detecting element. A concave portion, which inhibits an influence of a bottom flow which is flowed and inputted from a fit gap between an installing portion and a flow detecting element, is provided at a bottom surface of the installing portion of a plate which is positioned on a projected area of a cavity of the flow detecting element.

Flow measuring device

A flow measuring device includes a sub-bypass passage arranged to precede a bypass passage which is linked to a flow detecting element. Bypass passage wall surfaces, which are positioned adjacent the sub-bypass passage, are inclined toward a direction of a sub-inflow opening, and an inner-circumference-side wall surface and an outer-circumference-side wall surface of the sub-bypass passage are inclined toward a direction of a sub-outflow opening. The described structure minimizes variations in the size of the bypass passage due to build-up of foreign material, and results in a more stable flow velocity of measured fluid past the flow detecting element.

Flow measuring device having plurality of bending portions

An environment sensor arranged in a measuring chamber disposed in a circuit board receiving portion does not affect a flow of air through a bypass passage, and thus does not affect detection accuracy of a flow rate detection element arranged in the bypass passage. A recessed portion is disposed in a side surface of a base parallel to a flow direction A of intake air passing through a main passage and a communication port of the measuring chamber is disposed in the recessed portion, and thus the measuring chamber is unlikely to be infiltrated by fouling substances, water droplets, and the like contained in the intake air. The communication port has a small length dimension L, and thus an environment parameter of the intake air is likely to propagate to the measuring chamber and high levels of detection response, detection accuracy, and reliability are ensured for the environment sensor.

Flow rate measurement device

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

Provided is an intake air temperature detection apparatus mounted integrally with a flow rate measurement apparatus, the intake air temperature detection apparatus having temperature measurement precision improved by increasing thermal responsiveness of an intake air temperature detection part that is arranged in a measurement passage of the flow rate measurement apparatus and detects a temperature of intake air, which is a fluid to be measured. The intake air temperature measurement apparatus includes: the intake air temperature detection part for detecting a temperature of the intake air in the measurement passage of the flow rate measurement apparatus; and an intake air temperature detection circuit part arranged in a circuit accommodating part of the flow rate measurement apparatus, for generating a signal obtained by carrying out phase lead correction on a signal representing a result of detection by the intake air temperature detection part.

Physical amount measurement apparatus mounted integrally with flow rate measurement apparatus, and physical amount measurement method

A flow rate measuring apparatus includes: a flow rate detecting device placed in an intake passage; a detection circuit for outputting an analog signal varying depending on the flow rate; a conversion circuit for converting the analog signal to a digital signal; a temperature detecting device for detecting an ambient temperature; and a correction circuit for primarily correcting the digital signal using a gain and/or an offset (correction coefficient) that can set the temperature coefficient in any appropriate way. The gain and/or the offset vary depending on the temperature coefficient set in any appropriate way and the ambient temperature detected by the temperature detecting device. Also, a plurality of the gains and/or the offsets are set depending on the flow rate, allowing the temperature characteristic error in flow rate measurement to be reduced.

Flow rate measuring apparatus

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.

A flow rate measuring device includes: a bypass passage; a flow rate detecting element; and a flow rate measuring circuit. The bypass passage includes: an inflow port; an outflow port; and a plurality of bent portions. The plurality of bent portions include first to third bent portions for forming U-shapes, and a fourth bent portion for bending the bypass passage bent at the third bent portion so as to be parallel to a mainstream flowing direction. The flow rate detecting element is arranged inside the bypass passage in a part after bending at the fourth bent portion. A route connecting the inflow port and the flow rate detecting element as a straight line is blocked by an inner wall surface of the bypass passage on an outer peripheral side, which is formed between the first bent portion and the second bent portion.

Flow rate measuring device

In a flow sensor, an upstream heating element and a downstream heating element are disposed, respectively, upstream and downstream in a flow direction of a fluid so as to undergo mutual thermal interference. By controlling heating currents flown through the respective heating elements, an average temperature control portion maintains an average temperature of the two heating elements at a temperature predetermined degrees higher than a temperature of the fluid detected by a fluid temperature detection portion while a voltage ratio control portion performs control so that a temperature difference or a ratio of applied voltages between the two heating elements takes a predetermined value. A detection signal corresponding to a flow direction of the fluid is obtained from a state of the control on the heating currents and whether a flow direction of the fluid is forward or backward is determined.

Flow sensor and control system of internal combustion engine

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.

Dust with various particle diameters entering a bypass passage, particularly, relatively large dust with a particle diameter of 100 to 200 &#x3bc;m or so, is reliably caused to collide with a first step-shaped part, a second step-shaped part and a plate-like member to be sufficiently decelerated and reach a flow rate detecting device with low collision energy. This can prevent the flow rate detecting device from being damaged by collision of dust. Furthermore, the placement position of the plate-like member is optimized to suppress air turbulence at a flow rate detecting part, which achieves a good balance between flow rate detection accuracy and dust tolerance.

Provided is a thermal flow sensor capable of obtaining a flow rate detection signal that differs depending on a flow direction of a fluid, with a simple configuration and at low cost. The thermal flow sensor includes: a bridge circuit () for outputting a flow rate detection signal (VM); a fluid direction detection circuit () for outputting a fluid direction detection signal (VD); and an arithmetic circuit () configured to: generate a first output signal (VQF) and a second output signal (VQR) based on the flow rate detection signal (VM) and the fluid direction detection signal (VD); and select the first output signal (VQF) when the fluid direction detection signal (VD) shows normal flow and select the second output signal (VQR) when the fluid direction detection signal (VD) shows reverse flow, to thereby output a flow rate detection signal (VOUT).

Thermal flow sensor and method of generating flow rate detection signal by the thermal flow sensor

A thermal air flow meter comprises: a bridge circuit unit that incorporates a bridge circuit including a heating resistor and supplies a current to the heating resistor so that the temperature of the resistor is always set higher by a predetermined temperature than the temperature of intake air detected by an intake-air temperature detection resistor, and outputs an output signal Vm based on the current value supplied to the heating resistor, in accordance with a flow rate of the intake air; a differential amplifier unit that amplifies a voltage dependent on difference in temperature between an upstream heating resistor and downstream heating resistor; and a subtraction processor that subtracts from the output signal Vm a constant times an output voltage Vd1 from the differential amplifier unit, and outputs a correction output signal Vout.

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Tokyo, Japan

Yuji Ariyoshi