Method for determining the oil temperature in an internal combustion engine

• US 20040128059A1
• Filed: 10/23/2003
• Published: 07/01/2004
• Est. Priority Date: 04/23/2001
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Zhang, Hong, Kunz, Franz
• Granted Patent: US 7,069,141 B2
• Time in Patent Office: Days
• US Class Current: 701/114
• CPC Class Codes: F01M 1/18 Indicating or safety devices concerning lubricant level F01M11/06, F01M11/12
• CPC Class Codes: F01M 11/10 Indicating devices; Other safety devices
• CPC Class Codes: F01M 5/005 Controlling temperature of lubricant
• CPC Class Codes: F02D 2200/023 Temperature of lubricating oil or working fluid

Abstract

The oil temperature (TOIL) in the internal combustion engine is calculated using an oil temperature model, which draws upon at least one parameter that characterizes the operating point of the internal combustion engine. The differential value (TOIL_SENS_DIF) between the modeled temperature value of the oil temperature model (TOIL_MDL_SENS) and the measured temperature value (TOIL_SENS) of the oil, which is measured by the oil temperature sensor, is included as an input variable in the oil temperature model during an iterative calculation cycle of an oil temperature value (TOIL_MDL) of the oil temperature mode, said calculation cycle directly or indirectly following the method step involving the calculation of the differential value.

Claims

1. Method for determining the oil temperature in an internal combustion engine wherein the oil temperature is calculated by an oil temperature model and wherein one or more parameters characterizing the operating point of the internal combustion engine are included as input variables to the oil temperature model, characterized in that a modeled oil temperature sensor value of the oil temperature model (TOIL_MDL_SENS) is compared with a measured oil temperature value (TOIL_SENS) and the resulting differential value (TOIL_SENS_DIF) is included as an input variable to the oil temperature model in an iterative calculation cycle of another oil temperature value (TOIL_MDL) of the oil temperature model, said cycle indirectly or directly following the step of calculating the differential value (TOIL_SENS_DIF).

2. Method according to claim 1, characterized in that the measured oil temperature value (TOIL-SENS) is obtained by means of an oil temperature sensor.

3. Method according to one of claims 1 or 2, characterized in that the differential value (TOIL_SENS_DIF) between the modeled oil temperature sensor value (TOIL_MDL_SENS) and the measured oil temperature (TOIL_SENS) is additively or multiplicatively included in the oil temperature model.

4. Method according to one of the preceding claims, characterized in that an oil temperature sensor malfunction is detected if the differential value (TOIL_SENS_DIF) exceeds a first temperature threshold value or is below a second temperature threshold value.

5. Method according to claim 4, characterized in that when an oil temperature sensor malfunction is detected, a visual and/or audible signal is generated and/or an entry is made in a fault memory of a memory unit.

6. Method according to one of the preceding claims, characterized in that one or more of the variables coolant temperature (TCO), air mass flow (MAF), intake pipe pressure (ps), excess air ratio (X) are used as parameters characterizing the operating point of the internal combustion engine.