# US 2014/0360262 A1 · Flow Rate Measuring Device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0360262 A1 - Document ID: US20140360262A1 - Status: Published application - Kind: A1 - Application number: 14/369,285 - Filed: 2012-01-10 - Published: 2014-12-11 - Earliest claimed: 2012-01-10 - Assignees: Hitachi Automotive Systems, Ltd. - Applicants: Hitachi Automotive Systems, Ltd. - Inventors: Satoshi Asano; Masahiro Matsumoto; Hiroshi Nakano; Keiji Hanzawa; Ryosuke Doi - Web page: https://patentgrep.com/patent/US20140360262A1 ## CPC - G01F 1/684: Structural arrangements; Mounting of elements, e.g. in relation to fluid flow - G01F 1/6842: {with means for influencing the fluid flow} - G01F 1/6845: {Micromachined devices} - G01F 1/69: of resistive type - G01F 1/696: Circuits therefor, e.g. constant-current flow meters - G01F 5/00: Measuring a proportion of the volume flow - G01F 15/02: Compensating or correcting for variations in pressure, density or temperature - H10W 90/753: {between laterally-adjacent chips} - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract A flow rate measuring device with high precision is provided. The flow rate measuring device includes a sub-passage that takes a part of the fluid flowing in a main passage, first temperature measuring means for measuring a temperature of the fluid flowing in the passage, second temperature measuring means for measuring a temperature of a fluid flowing in the sub-passage, detecting means for detecting a flow rate of the fluid flowing in the sub-passage, and measuring means for measuring a flow rate of the fluid flowing within the main channel on the basis of an output of the first temperature measuring means, an output of the second temperature measuring means, and an output of the detecting means. ## Claims ### Claim 1 A flow rate measuring device comprising: a sub-passage that takes a part of the fluid flowing in a main passage; a sensor element that is disposed within the sub-passage; a first temperature sensor that measures a temperature of the fluid flowing in the main passage; and a second temperature sensor that is disposed within the sub-passage, and measures a temperature of a fluid different in temperature from the fluid flowing in the main passage. ### Claim 2 (depends on 1) The flow rate measuring device according to claim 1, wherein an air flow rate is measured on the basis of temperature information measured by the first temperature sensor and the second temperature sensor. ### Claim 3 (depends on 2) The flow rate measuring device according to claim 2, further comprising: measuring means for measuring a flow rate of the fluid flowing in the main passage on the basis of an output of the first temperature sensor, an output of the second temperature sensor, and an output of the sensor element. ### Claim 4 (depends on 3) The flow rate measuring device according to claim 3, wherein the measuring means includes a correction circuit that corrects an output of the sensor element on the basis of an output of the first temperature sensor and an output of the second temperature sensor. ### Claim 5 (depends on 4) The flow rate measuring device according to claim 4, wherein the correction circuit includes: deriving means for deriving a correction value based on a flow rate ratio of the main passage and the sub-passage on the basis of an output of the first temperature sensor and an output of the second temperature sensor; and converting means for converting the output of the sensor element into the flow rate of the fluid flowing into the main passage on the basis of the correction value. ### Claim 6 (depends on 1) The flow rate measuring device according to claim 1, wherein the sensor element includes a diaphragm formed on a semiconductor substrate, a heat generation resistor formed on the diaphragm, and temperature measuring resistors disposed upstream and downstream of the heat generation resistor in a flow of the fluid. ### Claim 7 (depends on 6) The flow rate measuring device according to claim 6, wherein a sub-diaphragm is disposed on the semiconductor substrate, and wherein the second temperature sensor is disposed on the sub-diaphragm. ### Claim 8 (depends on 6) The flow rate measuring device according to claim 6, wherein the sensor element and the correction circuit are mounted on a lead frame, wherein a sensor module in which the sensor element, the correction circuit, and the lead frame are integrally sealed by mold is formed, and wherein the sensor module has a mold opening portion so that the diaphragm is exposed to the fluid. ### Claim 9 (depends on 8) The flow rate measuring device according to claim 8, wherein the second temperature sensor is disposed within the sensor module, and an irregular portion is disposed on the sensor module surface. ### Claim 10 (depends on 9) The flow rate measuring device according to claim 9, wherein a sensor module surface of a portion on which the second temperature sensor is disposed is shaped into asperity. ### Claim 11 (depends on 7) The flow rate measuring device according to claim 7, wherein the sensor element and the correction circuit are mounted on a lead frame, wherein a sensor module in which the sensor element, the correction circuit, and the lead frame are integrally sealed by mold is formed, wherein the sensor module has a mold opening portion so that the diaphragm is exposed to the fluid, and wherein the sensor module has a mold opening portion so that the diaphragm is exposed to the fluid. ### Claim 12 (depends on 6) The flow rate measuring device according to claim 6, wherein the sub-passage has a bend, and the sensor element is disposed downstream of the bend in a flow of the fluid. ### Claim 13 (depends on 6) The flow rate measuring device according to claim 6, wherein the sub-passage includes a first sub-passage having two or more opening portions that communicate with the main passage, and a second sub-passage having one or more opening portions that communicate with the first sub-communication, and the sensor element is disposed within the second sub-passage. ### Claim 14 (depends on 13) The flow rate measuring device according to claim 13, wherein the second sub-passage has one or more opening portions that communicate with the first sub-passage with an angle of 90 degrees or more to a main flow direction of the fluid flowing in the first sub-passage. ### Claim 15 (depends on 12) The flow rate measuring device according to claim 12, wherein the second temperature sensor is located in the vicinity of the sensor element. ### Claim 16 (depends on 1) The flow rate measuring device according to claim 1, wherein the first temperature sensor is arranged to be exposed to the fluid flowing in the main passage, and wherein the second temperature sensor is arranged to be exposed to the fluid flowing in the sub-passage. ### Claim 17 (depends on 1) The flow rate measuring device according to claim 1, wherein the first temperature sensor is arranged upstream of the second temperature sensor in the flow of the fluid. ### Claim 18 (depends on 6) The flow rate measuring device according to claim 6, further comprising: a heat generation temperature detection resistor that detects a temperature of the heat generation resistor; and a fluid temperature detection resistor that detects the temperature of the fluid moving within the sub-passage, wherein a heat generation amount of the heat generation resistor is controlled so that a temperature of the heat generation temperature detection resistor becomes higher than a temperature of the fluid temperature detection resistor by a given temperature, and wherein the fluid temperature detection resistor is set as the second temperature sensor.