Abstract: A circuit board is located in a flow rate measurement passage of a housing. The flow rate measurement passage has: a first inner surface that is located at one side of the flow rate measurement passage where a primary lateral surface of the housing is placed; and a second inner surface that is located at another side of the flow rate measurement passage where a secondary lateral surface of the housing is placed. A flow rate sensing device is installed to one side of the circuit board where the first inner surface is placed. A distance, which is measured from the circuit board to the first inner surface in a plate thickness direction of the circuit board, is larger than a distance, which is measured from the circuit board to the second inner surface in the plate thickness direction of the circuit board.

Abstract: An air flow rate measurement device includes a housing, a flow rate sensing device and a physical quantity sensing device. The flow rate sensing device is located in a flow rate measurement passage of the housing and outputs a signal which corresponds to a flow rate of air flowing in the flow rate measurement passage. The physical quantity sensing device is located in a physical quantity measurement main passage of the housing that is communicated with a physical quantity measurement main passage inlet and a physical quantity measurement main passage outlet of the housing. The physical quantity sensing device outputs a signal which corresponds to a physical quantity of the air flowing in the physical quantity measurement main passage. The housing has the physical quantity measurement main passage outlet as one of a plurality of physical quantity measurement main passage outlets.

Abstract: A physical quantity measuring device is configured to measure a physical quantity of a fluid. The physical quantity measuring device includes: at least two humidity detection parts configured to output a humidity signal corresponding to a humidity of the fluid; and an abnormality determination part configured to determine that an abnormality has occurred in the humidity detection parts in response to that a difference between the humidity signals obtained from the two humidity detection parts exceeds an abnormality determination threshold.

Abstract: A physical quantity sensing device is installed to a circuit board and is configured to output a signal, which corresponds to a physical quantity of air flowing through a physical quantity measurement passage. A physical quantity measurement passage inlet, which is communicated with the physical quantity measurement passage, includes a first inner surface and a second inner surface. A second distance, which is measured from the physical quantity sensing device to the second inner surface in a plate thickness direction of the circuit board, is larger than a first distance, which is measured from the circuit board to the first inner surface in the plate thickness direction of the circuit board.

Abstract: A physical quantity sensing device is installed to a circuit board and is configured to output a signal, which corresponds to a physical quantity of air flowing through a physical quantity measurement passage. A physical quantity measurement passage inlet, which is communicated with the physical quantity measurement passage, includes a first inner surface and a second inner surface. A second distance, which is measured from the physical quantity sensing device to the second inner surface in a plate thickness direction of the circuit board, is larger than a first distance, which is measured from the circuit board to the first inner surface in the plate thickness direction of the circuit board.

Abstract: A physical quantity measuring device is configured to measure a physical quantity of a fluid. The physical quantity measuring device includes: at least two humidity detection parts configured to output a humidity signal corresponding to a humidity of the fluid; and an abnormality determination part configured to determine that an abnormality has occurred in the humidity detection parts in response to that a difference between the humidity signals obtained from the two humidity detection parts exceeds an abnormality determination threshold.

Abstract: An airflow-rate detecting device capable of detecting humidity has a housing, a flow rate sensor, a humidity sensor, a humidity sensor case, and a dust separating portion. The housing therein defines a bypass passage into which a part of air flowing in a duct flows. The flow rate sensor is disposed in the bypass passage. The humidity sensor detects a humidity of air flowing in the duct at an outside of the housing. The humidity sensor case houses the humidity sensor and therein defines an interior space into which a part of air flowing in the duct flows as a target air of which humidity is detected by the humidity sensor. The dust separating portion removes dust from the target air before the target air flows into the interior space.

Abstract: An airflow-rate detecting device capable of detecting humidity has a housing, a flow rate sensor, a humidity sensor, a humidity sensor case, and a dust separating portion. The housing therein defines a bypass passage into which a part of air flowing in a duct flows. The flow rate sensor is disposed in the bypass passage. The humidity sensor detects a humidity of air flowing in the duct at an outside of the housing. The humidity sensor case houses the humidity sensor and therein defines an interior space into which a part of air flowing in the duct flows as a target air of which humidity is detected by the humidity sensor. The dust separating portion removes dust from the target air before the target air flows into the interior space.

Abstract: An air flow measurement device arranged in an intake passage includes a bypass passage having an inlet from which a part of a main flow of an intake air is introduced, and an outlet from which the introduced intake air flows out. A sensor is located in the bypass passage to generate an electrical signal, and the bypass passage communicates with the intake passage through a hole portion. The outlet is open toward a downstream side of the intake passage in a flow direction of the main flow of the intake air. The hole portion is located within an outlet projected area that is provided by projecting an open area of the outlet in straight and toward upstream in the flow direction of the main flow on a projection surface perpendicular to the flow direction of the main flow.

Abstract: A flow measuring device includes a housing, a support, and a flow measurement element. The housing defines a passage therein and includes a passage narrowing part, which reduces a cross-sectional area of the passage, in a predetermined part of the passage. The support has a platy shape and is disposed along a flow direction of fluid flowing in the passage. The flow measurement element is located inside the passage narrowing part and is disposed on a surface of the support. The flow measurement element detects a flow rate of fluid flowing in the passage. The passage narrowing part has an inner wall surface that gradually reduces a width of the passage from a center side to both end sides of the passage in a height direction of the passage, which is perpendicular to a direction of the width of the passage.

Abstract: An air flow measurement device arranged in an intake passage includes a bypass passage having an inlet from which a part of a main flow of an intake air is introduced, and an outlet from which the introduced intake air flows out. A sensor is located in the bypass passage to generate an electrical signal, and the bypass passage communicates with the intake passage through a hole portion. The outlet is open toward a downstream side of the intake passage in a flow direction of the main flow of the intake air. The hole portion is located within an outlet projected area that is provided by projecting an open area of the outlet in straight and toward upstream in the flow direction of the main flow on a projection surface perpendicular to the flow direction of the main flow.

Abstract: A flow measuring device includes a housing, a support, and a flow measurement element. The housing defines a passage therein and includes a passage narrowing part, which reduces a cross-sectional area of the passage, in a predetermined part of the passage. The support has a platy shape and is disposed along a flow direction of fluid flowing in the passage. The flow measurement element is located inside the passage narrowing part and is disposed on a surface of the support. The flow measurement element detects a flow rate of fluid flowing in the passage. The passage narrowing part has an inner wall surface that gradually reduces a width of the passage from a center side to both end sides of the passage in a height direction of the passage, which is perpendicular to a direction of the width of the passage.

Abstract: A flow detecting device is provided to a fluid passage through which a main flow of fluid passes. A sensor body has a bypass passage through which a bypass flow passes from the main flow. The bypass passage has a bent portion, which is located midway through the bypass passage, and an outflow passage, which is located downstream of the bent portion. The flow direction of the bypass flow changes at the bent portion toward the outflow passage through the bypass passage. A heating element is arranged in the bypass passage. The heating element generates heat by being supplied with electricity for detecting a flow amount of fluid. The sensor body has a side surface defining an opening through which dynamic pressure caused by counterflow is released to an outside of the outflow passage when fluid causes counterflow in the fluid passage in a direction opposite to a flow direction of the main flow.

Abstract: A substrate includes a first surface portion, which covers a heat receiving portion of a radiation member together with a resinous member. The substrate further includes a second surface portion, which is on the outer periphery of the first surface portion. The substrate makes contact with the resinous member via the second surface portion. The first surface portion and the heat receiving portion have a first contact boundary therebetween. The second surface portion and the resinous member have a second contact boundary that surrounds the first contact boundary. The second contact boundary is sealed using a sealing member. The sealing member is restricted from flowing into a boundary between the first contact boundary and the second contact boundary.

Abstract: A substrate includes a first surface portion, which covers a heat receiving portion of a radiation member together with a resinous member. The substrate further includes a second surface portion, which is on the outer periphery of the first surface portion. The substrate makes contact with the resinous member via the second surface portion. The first surface portion and the heat receiving portion have a first contact boundary therebetween. The second surface portion and the resinous member have a second contact boundary that surrounds the first contact boundary. The second contact boundary is sealed using a sealing member. The sealing member is restricted from flowing into a boundary between the first contact boundary and the second contact boundary.

Abstract: A sensing unit is constructed of a heater element and a temperature sensing element. The sensing unit is arranged in a region, in which measurement air, which flows into the inflow passage through the bypass inlet, bends at the substantially right-angle and contracts in flow. Alternatively, the sensing unit is arranged in a region immediately after an area, in which the measurement air flowing through the bypass inlet bends at the substantially right-angle. The lengthwise directions of the heater element and the temperature sensing element are respectively arranged to be in parallel with both thickness-wise side faces of the measurement body. Thereby, even when a flow rate of measurement air changes, an influence due to the change can be restricted from being exerted. Therefore, the maximum flow rate can be measured within the lengthwise range of the heater element from a low flow rate to a high flow rate.

Abstract: A flow detecting device is provided to a fluid passage through which a main flow of fluid passes. A sensor body has a bypass passage through which a bypass flow passes from the main flow. The bypass passage has a bent portion, which is located midway through the bypass passage, and an outflow passage, which is located downstream of the bent portion. The flow direction of the bypass flow changes at the bent portion toward the outflow passage through the bypass passage. A heating element is arranged in the bypass passage. The heating element generates heat by being supplied with electricity for detecting a flow amount of fluid. The sensor body has a side surface defining an opening through which dynamic pressure caused by counterflow is released to an outside of the outflow passage when fluid causes counterflow in the fluid passage in a direction opposite to a flow direction of the main flow.

Abstract: An airflow meter has a bypass passage disposed in an air passage and a sensing portion disposed in the bypass passage to detect an airflow amount. The bypass passage is provided with a restriction portion to gradually decrease a passage width of the bypass passage in an airflow direction in the bypass passage. The restriction portion includes a first restriction portion and the second restriction portion disposed at an immediately downstream side of a narrowest portion of the first restriction portion. The first restriction portion gradually decreases the passage width in the airflow direction. The second restriction portion increases the passage width than the passage width at the narrowest portion in a stepped manner. The sensing portion is located in a bound in which the restriction portion is disposed.

Abstract: A sensing unit is constructed of a heater element and a temperature sensing element. The sensing unit is arranged in a region, in which measurement air, which flows into the inflow passage through the bypass inlet, bends at the substantially right-angle and contracts in flow. Alternatively, the sensing unit is arranged in a region immediately after an area, in which the measurement air flowing through the bypass inlet bends at the substantially right-angle. The lengthwise directions of the heater element and the temperature sensing element are respectively arranged to be in parallel with both thickness-wise side faces of the measurement body. Thereby, even when a flow rate of measurement air changes, an influence due to the change can be restricted from being exerted. Therefore, the maximum flow rate can be measured within the lengthwise range of the heater element from a low flow rate to a high flow rate.

Abstract: An airflow meter has a bypass passage disposed in an air passage and a sensing portion disposed in the bypass passage to detect an airflow amount. The bypass passage is provided with a restriction portion to gradually decrease a passage width of the bypass passage in an airflow direction in the bypass passage. The restriction portion includes a first restriction portion and the second restriction portion disposed at an immediately downstream side of a narrowest portion of the first restriction portion. The first restriction portion gradually decreases the passage width in the airflow direction. The second restriction portion increases the passage width than the passage width at the narrowest portion in a stepped manner. The sensing portion is located in a bound in which the restriction portion is disposed.