Abstract: An intake air flow detecting device is provided to an intake air passage, through which intake air flows into an internal combustion engine. Intake air flow is divided into a main passage and a bypass passage. The detecting device includes a thermal air flowmeter, a bypass flow delay information calculating means, and a response delay compensating means. The thermal air flowmeter includes a detector arranged in the bypass passage for detecting an air flow amount in the intake air passage. The bypass flow delay information calculating means calculates a bypass flow delay information representing delay in variation in a flow amount in the bypass passage with respect to variation in a flow amount in the main passage. The response delay compensating means compensates delay in response of the air flowmeter in accordance with the bypass flow delay information.

Abstract: A measurement body is provided with a sub-outlet arranged between a U-turn portion of a bypass passage and a main outlet. The sub-outlet includes a first sub-outlet positioned on a path of air, which flows on the inside of the bypass passage, and a second sub-outlet positioned on a path of air, which flows on the outside of the bypass passage. The respective sub-outlets open in a sidewall surface of the measurement body along the thickness-wise direction. However, the first sub-outlet and the second sub-outlet are arranged in different positions with respect to the flow direction of measurement air. With this structure, a substantial length of the bypass passage can be adjusted in accordance with positions of the first sub-outlet and the second sub-outlet, so that compensation of intake pulsation is enhanced in accuracy. Thereby, measurement error caused by influences of intake pulsation can be reduced.

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: A separator partitions an upstream side air passage of a bypass passage into first and second sub passages. A thermal flow sensor is attached to the separator facing the first sub passage. A convex is formed on the inner wall of an outer pipe defining the second sub passage. The convex protrudes toward the separator. Minimum flow passage area S2 of the second sub passage is smaller than minimum flow passage area S1 of the first sub passage, so that flow passage loss of the second sub passage is larger than flow passage loss of the first sub passage. Thus, measured air-flow amount average when the air-flow pulsates is corrected to be larger.

Abstract: A separator partitions an upstream side air passage of a bypass passage into first and second sub passages. A thermal flow sensor is attached to the separator facing the first sub passage. A convex is formed on the inner wall of an outer pipe defining the second sub passage. The convex protrudes toward the separator. Minimum flow passage area S2 of the second sub passage is smaller than minimum flow passage area S1 of the first sub passage, so that flow passage loss of the second sub passage is larger than flow passage loss of the first sub passage. Thus, measured air-flow amount average when the air-flow pulsates is corrected to be larger.

Abstract: A throttle device comprises a throttle valve having a circular body and a compensation member made of resin. The body has an upstream half rotatable at an upstream side with respect to a throttle shaft and a downstream half rotatable at a downstream side with respect thereto. The compensation member is installed on the upstream half at a downstream side thereof and bulged toward an inner wall of a throttle body. When the throttle valve rotates in an open direction from a closed position, the area of an intake air passage at the upstream half is smaller than the area of a passage at the downstream half and thus, the difference between the flow velocity at the upstream half and that at the downstream half can be reduced. Accordingly, it is possible to restrict the flow of the intake air from becoming oblique to the axis of the intake air passage and hence measure the flow rate of the intake air accurately.

Abstract: A flow meter for measuring a flow rate of fluid includes a body providing a main passage through which the fluid flows. A plurality of support elements connect an inner wall surface of the body and a central element so as to support the central element substantially at the center of the main passage. An introducing port opens to the central element for introducing a part of the fluid flowing through the main passage. A branch passage is formed within the central element, through which such part of the fluid flows. A sensor is disposed within the branch passage for measuring a flow rate within the branch passage. An outlet opens to a portion of the central element located at upperstream of the downstream ends of the support elements for returning the fluid flowing through the branch passages to the main passage.

Abstract: A flow meter for measuring a flow rate of fluid includes a body providing a main passage through which the fluid flows. A plurality of support elements connect an inner wall surface of the body and a central element so as to support the central element substantially at the center of the main passage. An introducing port opens to the central element for introducing a part of the fluid flowing through the main passage. A branch passage is formed within the central element, through which such part of the fluid flows. A sensor is disposed within the branch passage for measuring a flow rate within the branch passage. An outlet opens to a portion of the central element located at upperstream of the downstream ends of the support elements for returning the fluid flowing through the branch passages to the main passage.

Abstract: A flow meter includes a tubular member having a main passage in which fluid flows. A branch passage member disposed in the main passage has a branch passage in which the fluid flows. A support member connects the branch passage member and a wall of the tubular member, and supports the branch passage member within the main passage. A partition arrangement disposed in the branch passage divides the branch passage into a plurality of sub passages extending along a flow of the fluid. A flow-rate measuring resistor is disposed in a region of the branch passage downstream of the partition arrangement for sensing a rate of a flow of the fluid in the branch passage. A control circuit electrically connected to the flow-rate measuring resistor is operative for calculating a measurement value from an output signal of the flow-rate measuring resistor.