Thermal flow measuring device (1), especially for determining and/or monitoring the mass flow (Φ.sub.M) and/or the flow velocity (v.sub.F) of a flowable medium (3) through a pipeline (2), comprising at least three sensor elements (4a,4b,4c) and an electronics unit (9), wherein each of the at least three sensor elements (4a,4b,4c) is at least partially and/or at times in thermal contact with the medium (3), and includes a heatable temperature sensor (5a,5b,5c), and wherein the electronics unit (9) is embodied to heat each of the three sensor elements (4a,4b,4c) with a heating power (P1,P2,P3), to register their temperatures (T1,T2,T3), to heat at least two of the at least three sensor elements (4a,4b,4c) simultaneously, to ascertain the mass flow (Φ.sub.M) and/or the flow velocity (v.sub.F) of the medium (3), from a pairwise comparison of the temperatures (T1,T2,T3) and/or heating powers (P1,P2,P3) of the at least three sensor elements (4a,4b,4c) and/or at least one variable derived from at least one of the temperatures (T1,T2,T3) and/or heating powers (P1,P2,P3), to provide information concerning a change of the thermal resistance of at least one of the at least three sensor elements (4a,4b,4c), from a response to an abrupt change ΔP of the heating power supplied to at least one of the at least three sensor elements, to provide information concerning a change of the inner thermal resistance of the at least one sensor element, and in the case that a change of the inner and/or outer thermal resistance occurs in the case of at least one of the at least three sensor elements (4a,4b,4c), to perform a correction of the measured value for the mass flow (Φ.sub.M) and/or the flow velocity (v.sub.F) and/or to generate and to output a report concerning the state of the at least one sensor element mass flow (Φ.sub.M) and/or the flow velocity (v.sub.F).

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.

The present disclosure provides an air flow rate measuring including a casing and a sensor. The casing includes a main-bypass passage that defines an inlet and an outlet, a sub-bypass passage that branches off from the main-bypass passage at a branching area, and a guiding wall that changes, at a position upstream of the branching area, a flow direction of the passing air taken in from the inlet. The inlet and the guiding wall are arranged in an arranging direction along a flow direction of the intake air in the duct. The guiding wall includes an inlet side surface that faces the inlet and is not perpendicular to the arranging direction.

An air cleaner includes a housing having an air inlet and an air outlet. The air cleaner further includes a filter media coupled to the housing and positioned between the air inlet and the air outlet, the filter media configured to filter an air flow that enters the housing through the air inlet and exits the housing through the air outlet. The air cleaner includes a rectifier coupled to the housing and positioned at a location downstream of the filter media, the rectifier including an outer ring that is orthogonally oriented with respect to the air flow.

An air flow measuring device includes a housing, a sensing part, a temperature sensor, a supporting member, and a protective projection. The housing defines a bypass flow passage which guides a part of air flowing in a duct. The sensing part is disposed in the bypass flow passage to measure a flow rate of air in the bypass flow passage. The sensor detects temperature of air flowing in the duct outside the housing. The supporting member supports the sensor at a predetermined measurement position. The protective projection is a projection, which projects outward from a side surface of the housing and is formed by mold removal in one direction. An end of the protective projection is located outward of the sensor. The protective projection makes contact with an object approaching the sensor from outside the housing to limit contact of the object with the sensor.

A sensor is provided for determining at least one parameter of a fluid medium flowing through a measurement channel, in particular an intake air mass flow of an internal combustion engine. The sensor has a sensor housing, in particular a plug-in sensor that is inserted into or is insertable into a flow tube, in which sensor a measurement channel is fashioned, and has at least one sensor chip situated in the measurement channel for determining the parameter of the fluid medium. The sensor housing has an electronics compartment for accommodating an electronics module and has an electronics compartment cover for closing the electronics compartment. The electronics compartment cover has, at least in part, electrically conductive properties. For example, the electronics compartment cover is placed onto the electrical ground of the sensor and, viewed in projection, partly or completely covers the sensor chip.

A flowmeter is inserted into a main passage through which a target fluid flows. The flowmeter includes a housing, a sub passage, an inlet portion, an outlet portion, a flow rate detector, and a protrusion. The housing includes a side surface and a tip end surface. A part of the target fluid flows into the sub passage from the main passage. The target fluid flows into the sub passage through the inlet portion and flows out of the sub passage through the outlet portion. The flow rate detector is configured to detect a flow rate of the target fluid flowing through the sub passage. The tip end surface includes a first end area and a second end area. The protrusion protrudes from the tip end surface and is located in both the first end area and the second end area.

The present invention provides a thermal flow meter which can suppress a degradation of measurement accuracy caused by deformation of a diaphragm and a stained rear surface thereof even in a case where a gap is provided in order to form the diaphragm in an air flow sensing element. The present invention relates to a thermal flow meter 300 which includes a bypass passage through which a measurement target gas 30 received from a main passage 124 flows, and an air flow sensing element which measures a flow rate of the measurement target gas 30 by performing heat transfer with the measurement target gas 30 flowing through the bypass passage. The thermal flow meter 300 includes at least a circuit package 400 which contains the air flow sensing element 602. A gap 674 is formed in a rear surface of the air flow sensing element 602 to form a diaphragm 672 in an air flow sensing area 437 of the air flow sensing element 602, and the gap 674 becomes a sealed space reduced in pressure compared to an atmospheric pressure.

A flow measurement probe includes an elongate probe having an averaging pitot tube with a plurality of upstream and downstream openings arranged along a length of the elongate probe, and a thermal flow measurement sensor coupled to the elongate probe. A method of measuring fluid flow rate in a process includes calculating a flow rate of the fluid using differential pressure in upstream and downstream openings of an averaging pitot tube in an elongate probe when the differential pressure is at least a defined measurement threshold, and calculating the flow rate of the fluid with a thermal mass flow sensor coupled to the flow measurement probe when the differential pressure is less than the defined measurement threshold.

The present disclosure provides a flow rate measuring device for measuring a flow rate of a main flow flowing through a duct. The flow rate measuring device includes a bypass passage, a blow rate sensor, and a measurement body. The measurement body includes a measurement flow inlet and a cylindrical portion. The measurement flow inlet is open toward an upstream side of the duct. The measurement flow outlet is open toward a downstream side of the duct. The cylindrical portion is disposed to cover the measurement flow outlet. The cylindrical portion includes an outer circumferential surface, which guides the main flow, and an inner circumferential surface, which guides the measurement flow. The cylindrical portion includes a waveform portion that is formed in an edge side of an opening of the cylindrical. The waveform portion has a shape that divides the main flow guided by the cylindrical portion into a plurality of main flows and that divides the measurement flow guided by the cylindrical portion into a plurality of measurement flows.