System and method for engine oil temperature estimation
AssigneeFord Global Technologies, LLC
InventorsErol Dogan Sumer, Yan Wang
Life of this patent
Estimating the term…
Abstract
Methods and systems are provided for estimating engine oil temperature during conditions when sensors used for engine oil temperature measurement are not functional or not reliable. A null duty cycle of a solenoid spool valve of a variable cam timing mechanism is estimated. Then, a calibrated relationship between the duty cycle, an angular velocity of the associated cam, and the engine oil temperature is used to estimate an engine oil temperature when existing sensors used in the calculation of engine oil temperature calculation become unreliable.
Claims20
An engine method, comprising:
- adjusting an engine torque actuator based on engine oil temperature estimated by applying an excitation signal, including one of a pulse-width modulated duty cycle, a voltage, and an electrical current, to a solenoid valve of a variable camshaft timing device, and using a mapped relationship, stored in non-volatile memory, relating camshaft solenoid duty cycle and camshaft angular velocity of the device to the engine oil temperature.
A method, comprising:
- during an engine cold-start condition, estimating an engine oil temperature based on each of measured engine coolant temperature, measured ambient temperature, and measured air charge temperature;
- and
- during an engine warm-start condition, estimating the engine oil temperature based on a mapped relationship between solenoid duty cycle of a spool valve of a variable cam timing device, angular velocity of a cam actuated by the spool valve, and the engine oil temperature.
An engine system, comprising:
- a variable cam timing (VCT) device including a cam, a camshaft phaser, a camshaft, a spool valve, and a solenoid;
- a cam position sensor coupled to the cam;
- a battery;
- an engine coolant temperature sensor;
- an intake air charge temperature sensor;
- a mass air flow sensor;
- and
- a controller including computer-readable instructions stored on non-transitory memory for:
- responsive to at least one diagnostic flag related to engine oil temperature estimation being set,
- applying an excitation pulse to the solenoid to move the spool valve, a duty cycle of the excitation pulse adjusted to move the cam outside of a hard-stop region;
- measuring an angular velocity of the camshaft following the applying via the cam position sensor;
- estimating a null duty cycle of the spool valve based on the applied duty cycle;
- and
- estimating an engine oil temperature based on a mapped relationship between the estimated null duty cycle and the measured angular velocity.
Dependencies are inferred from the claim text.