# US 10,119,455 B2 · Method and system for detecting thermostat failure in an engine cooling system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,119,455 B2 - Document ID: US10119455B2 - Status: Granted - Kind: B2 - Application number: 15/263,442 - Filed: 2016-09-13 - Published: 2018-03-15 - Granted: 2018-11-06 - Earliest claimed: 2016-09-13 - Assignees: Caterpillar Inc. - Applicants: Caterpillar Inc. - Inventors: Jeffrey Joseph Speichinger - Web page: https://patentgrep.com/patent/US10119455B2 ## CPC - F01P 11/16: concerning coolant temperature (F01P11/20 takes precedence) - G01M 15/048: {by monitoring temperature} - F01P 2025/04: Pressure - F01P 2025/30: Engine incoming fluid temperature - F01P 2025/32: Engine outcoming fluid temperature - F01P 2031/20: Warning devices - 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) - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR ## Abstract A method for thermostat failure detection in an engine cooling system is provided. The engine cooling system includes a coolant pump and a thermostat for providing a coolant flow between an engine and a radiator. The method includes determining one or more engine parameters. Further, a pressure difference between a coolant pump inlet pressure and a coolant pump outlet pressure is determined corresponding to the one or more engine parameters. The thermostat failure is detected when the determined pressure difference is outside a predefined range of pressure change defined corresponding to the determined one or more engine parameters. ## Claims ### Claim 1 A method for detecting thermostat failure in an engine cooling system, the engine cooling system having a coolant pump and a thermostat for providing a coolant flow between an engine and a radiator, the method comprising: determining one or more engine parameters; determining a pressure difference between a coolant pump outlet pressure and a coolant pump inlet pressure corresponding to the determined one or more engine parameters; and detecting the thermostat failure when the determined pressure difference is outside a predefined range of pressure change defined corresponding to the determined one or more engine parameters. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein the one or more engine parameters include at least one of an engine speed and a coolant temperature. ### Claim 3 (depends on 2) The method as claimed in claim 2 further comprising: determining the pressure difference corresponding to an engine speed corresponding to a coolant temperature range; and detecting the thermostat failure when the pressure difference determined for a coolant temperature, falling within the coolant temperature range, is outside the predefined range of pressure change defined for the coolant temperature range. ### Claim 4 (depends on 1) The method as claimed in claim 1, wherein the predefined range of pressure change is determined during normal operation of the thermostat. ### Claim 5 (depends on 1) The method as claimed in claim 1, wherein the predefined range of pressure change is in the form of at least one of a curve, a map, or a look-up table. ### Claim 6 (depends on 1) The method as claimed in claim 1 further comprising transmitting a notification signal, indicative of the thermostat failure, to a display device. ### Claim 7 A control system for detecting thermostat failure in an engine cooling system, the engine cooling system having a coolant pump and a thermostat for providing coolant flow between an engine and a radiator, the control system comprising: a first pressure sensor associated with a coolant pump outlet and configured to monitor a coolant pump outlet pressure; a second pressure sensor associated with a coolant pump inlet and configured to monitor a coolant pump inlet pressure; and a controller operatively coupled to the first pressure sensor and the second pressure sensor, the controller being configured to: determine one or more engine parameters; determine a pressure difference between the coolant pump outlet pressure and the coolant pump inlet pressure corresponding to the determined one or more engine parameters; and detect the thermostat failure when the determined pressure difference is outside a predefined range of pressure change defined for the determined one or more engine parameters. ### Claim 8 (depends on 7) The control system as claimed in claim 7, wherein the one or more engine parameters include at least one of engine speed or coolant temperature. ### Claim 9 (depends on 8) The control system as claimed in claim 8, wherein the controller is configured to: determine the pressure difference corresponding to an engine speed corresponding to a coolant temperature range; and detect the thermostat failure when the pressure difference determined for the coolant temperature, falling within the coolant temperature range, is outside the predefined range of pressure change defined for the coolant temperature range. ### Claim 10 (depends on 7) The control system as claimed in claim 7, wherein the predefined range of pressure change is determined during normal operation of the thermostat. ### Claim 11 (depends on 7) The control system as claimed in claim 7, wherein the predefined range of pressure change is in the form of at least one of a curve, a map, or a look-up table. ### Claim 12 (depends on 7) The control system as claimed in claim 7, wherein the controller is further configured to transmit a notification signal, indicative of the thermostat failure, to a display device. ### Claim 13 An engine cooling system for an engine, the engine cooling system comprising: a radiator; a coolant pump configured to circulate coolant through the engine and the radiator; a thermostat configured to regulate coolant flow between the engine and the radiator based on one or more engine parameters; and a control system comprising: a first pressure sensor associated with a coolant pump outlet and configured to monitor a coolant pump outlet pressure; a second pressure sensor associated with a coolant pump inlet and configured to monitor a coolant pump inlet pressure; and a controller operatively coupled to the first pressure sensor and the second pressure sensor, the controller being configured to: determine one or more engine parameters; determine a pressure difference between the coolant pump outlet pressure and the coolant pump inlet pressure corresponding to the determined one or more engine parameters; and detect the thermostat failure when the determined pressure difference is outside a predefined range of pressure change defined for the determined one or more engine parameters. ### Claim 14 (depends on 13) The engine cooling system as claimed in claim 13, wherein the one or more engine parameters include at least one of engine speed or coolant temperature. ### Claim 15 (depends on 14) The engine cooling system as claimed in claim 14, wherein the controller is configured to: determine the pressure difference corresponding to an engine speed corresponding to a coolant temperature range; and detect the thermostat failure when the pressure difference determined for the coolant temperature, falling within the coolant temperature range, is outside the predefined range of pressure change defined for the coolant temperature range. ### Claim 16 (depends on 13) The engine cooling system as claimed in claim 13, wherein the predefined range of pressure change is determined during normal operation of the thermostat. ### Claim 17 (depends on 13) The engine cooling system as claimed in claim 13, wherein the predefined range of pressure change is in the form of at least one of a curve, a map, or a look-up table. ### Claim 18 (depends on 13) The engine cooling system as claimed in claim 13, wherein the controller is further configured to transmit a notification signal, indicative of the thermostat failure, to a display device.