Abstract: A measurement structure that projects into an intake passage is provided with a shunt plate adjacent to a first passage that extends from an air inlet to an air outlet. A second passage is formed around the shunt plate so as to bypass the first passage. An air flow rate measuring element is disposed in the second passage. An edge of the shunt plate is located on a imaginary line or distant from the imaginary line to the second passage side, in which the imaginary line is parallel to the axis of the intake passage and passing through the top of the air inlet, whereby dust or liquid matter is prevented from entering the second passage. Alternatively, the shunt plate is provided with an inclined portion which is projected to the first passage so that the inclined portion is inclined toward the air outlet. As a further alternative, the shunt plate is provided with an inclined portion that is inclined toward the air inlet and has a through-hole.

Abstract: An air flow rate measuring device serves to measure a flow rate of air flowing through a main passage inside an intake pipe of an engine. A base has its one end directed axially of the main passage toward an upstream side of air flowing therein, and its other end directed toward a downstream side thereof, with a bent groove being formed in the base. A circuit module includes a support substrate and a detection element installed one surface of the support substrate for detecting the flow rate of air, the module being joined to the base in a face-to-face relation with respect to each other to form an auxiliary passage in cooperation with the groove. The detection element on the one surface of the support substrate is exposed to air in the auxiliary passage, and the other surface of the support substrate is exposed to air in the main passage.

Abstract: An air flow rate measuring device serves to measure a flow rate of air flowing through a main passage inside an intake pipe of an engine. A base has its one end directed axially of the main passage toward an upstream side of air flowing therein, and its other end directed toward a downstream side thereof, with a bent groove being formed in the base. A circuit module includes a support substrate and a detection element installed one surface of the support substrate for detecting the flow rate of air, the module being joined to the base in a face-to-face relation with respect to each other to form an auxiliary passage in cooperation with the groove. The detection element on the one surface of the support substrate is exposed to air in the auxiliary passage, and the other surface of the support substrate is exposed to air in the main passage.

Abstract: A measurement structure that projects into an intake passage is provided with a shunt plate adjacent to a first passage that extends from an air inlet to an air outlet. A second passage is formed around the shunt plate so as to bypass the first passage. An air flow rate measuring element is disposed in the second passage. An edge of the shunt plate is located on a imaginary line or distant from the imaginary line to the second passage side, in which the imaginary line is parallel to the axis of the intake passage and passing through the top of the air inlet, whereby dust or liquid matter is prevented from entering the second passage. Alternatively, the shunt plate is provided with an inclined portion which is projected to the first passage so that the inclined portion is inclined toward the air outlet. As a further alternative, the shunt plate is provided with an inclined portion that is inclined toward the air inlet and has a through-hole.

Abstract: A post in a fluid passage for passing a fluid flow extends across a part of the fluid flow; a measuring duct in the post extends through the post; and a flow rate detector is located in the measuring duct. The measuring duct has a fluid introduction port with an elongated shape, the measuring duct is constricted and has at least a portion located between the fluid introduction port and the flow rate detector, substantially smoothly narrowing toward a downstream direction of the flow in a longitudinal direction of the elongated shape.

Abstract: A circuit case is disposed integrally on a first side of a joint portion formed with a circular cross section, and a measuring conduit is disposed so as to extend from a second side of the joint portion. A pair of mounting portions are disposed so as to extend in flange shapes from the circuit case on mutually opposite sides of the joint portion, and a mounting aperture is disposed through each of the mounting portions. A lower surface of each of the mounting portions is formed so as to have a stepped portion, a wall surface of the stepped portion constituting a position regulating portion.

Abstract: In a flow rate sensor, a sensing passage, into which a fluid is introduced and in which a flow rate sensing element is disposed, a support member for supporting the sensing passage, and a circuit case, in which an electronic circuit unit for controlling the flow rate sensing element is accommodated, are formed integrally with each other, and the support member extends into a main passage through a hole opened to the main passage so as to position the sensing passage in the main passage. A structural member, the outside shape of which is formed to have a fluid resistance approximately similar to that of the portion of the support member extending from the hole, is disposed at a position approximately symmetrical with the portion of the support member extending from the hole about the sensing passage.

Abstract: A circuit case is disposed integrally on a first side of a joint portion formed with a circular cross section, and a measuring conduit is disposed so as to extend from a second side of the joint portion. A pair of mounting portions are disposed so as to extend in flange shapes from the circuit case on mutually opposite sides of the joint portion, and a mounting aperture is disposed through each of the mounting portions. A lower surface of each of the mounting portions is formed so as to have a stepped portion, a wall surface of the stepped portion constituting a position regulating portion.

Abstract: In a flow rate sensor, a sensing passage, into which a fluid is introduced and in which a flow rate sensing element is disposed, a support member for supporting the sensing passage, and a circuit case, in which an electronic circuit unit for controlling the flow rate sensing element is accommodated, are formed integrally with each other, and the support member extends into a main passage through a hole opened to the main passage so as to position the sensing passage in the main passage. A structural member, the outside shape of which is formed to have a fluid resistance approximately similar to that of the portion of the support member extending from the hole, is disposed at a position approximately symmetrical with the portion of the support member extending from the hole about the sensing passage.

Abstract: A flow rate-measuring device capable of measuring accurately a flow rate of fluid to be measured containing a drift or eddy as compared with a conventional device is provided. A flow rate-measuring passage 11 for measuring a flow rate of the fluid to be measured is constructed so that its opening area in an upstream region communicating to an inlet 111 gradually decreases from upstream to downstream. A flow rate-detecting element 31 is disposed near an outlet in the flow rate-measuring passage 11. The device is provided with a leak flow passage 18 allowing a part of the fluid which has flown in from the inlet 111 of the flow rate-measuring passage 11 to leak out of the flow rate-measuring passage 11 at a portion upstream from an outlet 112 of the flow rate-measuring passage 11, in particular upstream from a position where the flow rate-detecting element 31 is disposed.

Abstract: In a flow rate sensor, a sensing passage, into which a fluid is introduced and in which a flow rate sensing element is disposed, a support member for supporting the sensing passage, and a circuit case, in which an electronic circuit unit for controlling the flow rate sensing element is accommodated, are formed integrally with each other, and the support member extends into a main passage through a hole opened to the main passage so as to position the sensing passage in the main passage. A structural member, the outside shape of which is formed to have a fluid resistance approximately similar to that of the portion of the support member extending from the hole, is disposed at a position approximately symmetrical with the portion of the support member extending from the hole about the sensing passage.

Abstract: In a flow rate sensor, a sensing passage, into which a fluid is introduced and in which a flow rate sensing element is disposed, a support member for supporting the sensing passage, and a circuit case, in which an electronic circuit unit for controlling the flow rate sensing element is accommodated, are formed integrally with each other, and the support member extends into a main passage through a hole opened to the main passage so as to position the sensing passage in the main passage. A structural member, the outside shape of which is formed to have a fluid resistance approximately similar to that of the portion of the support member extending from the hole, is disposed at a position approximately symmetrical with the portion of the support member extending from the hole about the sensing passage.

Abstract: A heat-sensitive flow rate sensor that is high in productivity, superior in accuracy of flow rate measurement and sensitivity. A bottom face of a concave accommodating portion 18 of an supporting member 16 is provided with an adhesion face 24 for fastening a flow rate-detecting element 14 thereon with an adhesive 15, installation faces 25a, 25b for holding the flow rate-detecting element 14 thereon, and a protruding face 26 for blocking in a raised manner the whole area of a cavity 13 on the underside of the flow rate-detecting element 14. As a result of employing this construction, even when increasing an intake fluid to a large amount of flow, the protruding face 26 blocks the vicinity of the cavity 13. Therefore, the fluid to be measured hardly flows into the gap between the underside of the flow rate-detecting element 14 and the supporting member 16. Consequently, accuracy in flow rate measurement is improved.

Abstract: In a flow rate sensor, a sensing passage, into which a fluid is introduced and in which a flow rate sensing element is disposed, a support member for supporting the sensing passage, and a circuit case, in which an electronic circuit unit for controlling the flow rate sensing element is accommodated, are formed integrally with each other, and the support member extends into a main passage through a hole opened to the main passage so as to position the sensing passage in the main passage. A structural member, the outside shape of which is formed to have a fluid resistance approximately similar to that of the portion of the support member extending from the hole, is disposed at a position approximately symmetrical with the portion of the support member extending from the hole about the sensing passage.

Abstract: A thermo-sensitive flow rate sensor that has a flow rate detecting device, in which a heating element constituted by thermo-sensitive resistor film, is formed on a top surface of a plate-like substrate and in which a diaphragm is formed by partially removing the plate-like substrate. This sensor further has a supporting element arranged in such a way as to have a top surface that is parallel to the direction of flow of a fluid to be measured. The flow rate detecting device is supported and fixed in a recess portion formed in the supporting element so that the top surface of the device is nearly flush with the top surface of the supporting element. Further, the thin-plate-like member is attached to the back surface of the flow rate detecting device in such a way as to close a cavity.

Abstract: To effect stable connection of an electrode of a sensing element to a connecting terminal, a holder for disposing the sensing element in a predetermined flow passage is provided. The holder is further provided with a rectification structure portion for rectifying the flow of an intake fluid and a connecting terminal securing portion with the connecting terminal embedded therein for fetching a signal of the sensing element, wherein the rectification structure portion and the connecting terminal securing portion are integrally formed by insulating material.

Abstract: A heat-sensitive flow rate sensor that is high in productivity, superior in accuracy of flow rate measurement and sensitivity. A bottom face of a concave accommodating portion 18 of an supporting member 16 is provided with an adhesion face 24 for fastening a flow rate-detecting element 14 thereon with an adhesive 15, installation faces 25a, 25b for holding the flow rate-detecting element 14 thereon, and a protruding face 26 for blocking in a raised manner the whole area of a cavity 13 on the underside of the flow rate-detecting element 14. As a result of employing this construction, even when increasing an intake fluid to a large amount of flow, the protruding face 26 blocks the vicinity of the cavity 13. Therefore, the fluid to be measured hardly flows into the gap between the underside of the flow rate-detecting element 14 and the supporting member 16. Consequently, accuracy in flow rate measurement is improved.

Abstract: A flow rate-measuring device capable of measuring accurately a flow rate of fluid to be measured containing a drift or eddy as compared with a conventional device is provided.

Abstract: In a flow rate sensor, a sensing passage, into which a fluid is introduced and in which a flow rate sensing element is disposed, a support member for supporting the sensing passage, and a circuit case, in which an electronic circuit unit for controlling the flow rate sensing element is accommodated, are formed integrally with each other, and the support member extends into a main passage through a hole opened to the main passage so as to position the sensing passage in the main passage. A structural member, the outside shape of which is formed to have a fluid resistance approximately similar to that of the portion of the support member extending from the hole, is disposed at a position approximately symmetrical with the portion of the support member extending from the hole about the sensing passage.

Abstract: In a flow rate sensor, a sensing passage, into which a fluid is introduced and in which a flow rate sensing element is disposed, a support member for supporting the sensing passage, and a circuit case, in which an electronic circuit unit for controlling the flow rate sensing element is accommodated, are formed integrally with each other, and the support member extends into a main passage through a hole opened to the main passage so as to position the sensing passage in the main passage. A structural member, the outside shape of which is formed to have a fluid resistance approximately similar to that of the portion of the support member extending from the hole, is disposed at a position approximately symmetrical with the portion of the support member extending from the hole about the sensing passage.