# US 10,119,887 B2 · Thermostat malfunction detection device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,119,887 B2 - Document ID: US10119887B2 - Status: Granted - Kind: B2 - Application number: 15/392,308 - Filed: 2016-12-28 - Published: 2017-08-10 - Granted: 2018-11-06 - Earliest claimed: 2016-02-04 - Assignees: Subaru Corporation - Applicants: Fuji Jukogyo Kabushiki Kaisha - Inventors: Masaki Kuhara - Web page: https://patentgrep.com/patent/US10119887B2 ## CPC - G01M 15/048: {by monitoring temperature} - F01P 11/16: concerning coolant temperature (F01P11/20 takes precedence) - G01K 3/005: {Circuits arrangements for indicating a predetermined temperature (fire detection G08B17/00)} - G01K 7/427: {Temperature calculation based on spatial modeling, e.g. spatial inter- or extrapolation} - G01M 99/00: Subject matter not provided for in other groups of this subclass - F01P 2031/32: Deblocking of damaged thermostat - G01K 2205/00: Application of thermometers in motors, e.g. of a vehicle - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR - F01P: COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES (arrangements in connection with cooling of propulsion units in vehicles B60K11/00; heat-transfer, heat-exchange or heat-storage materials C09K5/00; {cooling of gas-turbine engines F02C7/12}; heat exchange in general, radiators F28) - G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00) ## Abstract A thermostat malfunction detection device that detects a stuck open state of a thermostat includes: an estimated water temperature calculation module that calculates an estimated water temperature of a cooling water based on an operation state of an engine; an actual water temperature detection unit that detects an actual water temperature of the cooling water; a first determination module that establishes preliminary determination when an amount of change of a difference between the estimated water temperature and the actual water temperature within a determined period is equal to or larger than a first threshold value; a passing air amount control module that increases a passing air amount, when the preliminary determination is established; and a second determination module that establishes malfunction determination, when the difference is equal to or larger than a second threshold value, after the passing air amount has been increased. ## Claims ### Claim 1 A thermostat malfunction detection device that detects a stuck open state of a thermostat that opens and closes a cooling water flow channel between a radiator including a passing air amount changing unit that increases and decreases a passing air amount and an engine, according to a temperature of a cooling water, comprising: an estimated water temperature calculation module that is configured to calculate an estimated water temperature of the cooling water based on an operation state of the engine; an actual water temperature detection unit that is configured to detect an actual water temperature of the cooling water; a first determination module that is configured to establish preliminary determination based on an amount of change of a difference between the estimated water temperature and the actual water temperature within a predetermined period during cooling water temperature rising is equal to or larger than a first threshold value; a passing air amount control module that is configured to control the passing air amount changing unit to increase a passing air amount, based on establishment of the preliminary determination by the first determination module; and a second determination module that is configured to establish malfunction determination, based on the difference between the estimated water temperature and the actual water temperature being equal to or larger than a second threshold value, after the passing air amount control module has increased the passing air amount. ### Claim 2 (depends on 1) The thermostat malfunction detection device according to claim 1, wherein the passing air amount changing unit includes a shutter that is configured to open and close at least a part of an air flow channel that introduces traveling wind from outside a vehicle body, and the passing air amount control module is further configured to set the shutter in an open state based on establishment of the preliminary determination. ### Claim 3 (depends on 1) The thermostat malfunction detection device according to claim 1, wherein the passing air amount changing unit includes an electric fan disposed to face the radiator, and the passing air amount control module is further configured to set the electric fan in a blowing state based on establishment of the preliminary determination. ### Claim 4 (depends on 2) The thermostat malfunction detection device according to claim 2, wherein the passing air amount changing unit includes an electric fan disposed to face the radiator, and the passing air amount control module is further configured to set the electric fan in a blowing state based on establishment of the preliminary determination. ### Claim 5 (depends on 1) The thermostat malfunction detection device according to claim 1, wherein the first determination module is further configured to establish the preliminary determination, based on a state in which a traveling speed of a vehicle is equal to or higher than a determined value that continues for at least a preset period. ### Claim 6 (depends on 2) The thermostat malfunction detection device according to claim 2, wherein the first determination module is further configured to establish the preliminary determination, based on a state in which a traveling speed of a vehicle is equal to or higher than a determined value that continues for at least a preset period. ### Claim 7 (depends on 3) The thermostat malfunction detection device according to claim 3, wherein the first determination module is further configured to establish the preliminary determination, based on a state in which a traveling speed of a vehicle is equal to or higher than a determined value that continues for at least a preset period. ### Claim 8 (depends on 4) The thermostat malfunction detection device according to claim 4, wherein the first determination module is further configured to establish the preliminary determination, based on a state in which a traveling speed of a vehicle is equal to or higher than a determined value that continues for at least a preset period. ### Claim 9 A thermostat malfunction detection device that detects a stuck open state of a thermostat that opens and closes a cooling water flow channel between a radiator including a passing air amount changing unit that increases and decreases a passing air amount and an engine, according to a temperature of a cooling water, comprising: an actual water temperature detection unit that is configured to detect an actual water temperature of the cooling water; and circuitry configured to: calculate an estimated water temperature of the cooling water based on an operation state of the engine, establish preliminary determination based on an amount of change of a difference between the estimated water temperature and the actual water temperature within a determined period during rise of cool water temperature is equal to or larger than a first threshold value, control the passing air amount changing unit to increase a passing air amount, based on establishment of the preliminary determination, and establish malfunction determination, based on the difference between the estimated water temperature and the actual water temperature being equal to or larger than a second threshold value, after the passing air amount has increased.