Methods and systems are provided for diagnosing an in-range error of a pressure sensor arranged downstream of a lift pump in a fuel system of a vehicle. In one example, a method may include performing feedback control of the lift pump based on output of the pressure sensor, monitoring the pressure s
Methods and systems are provided for diagnosing an in-range error of a pressure sensor arranged downstream of a lift pump in a fuel system of a vehicle. In one example, a method may include performing feedback control of the lift pump based on output of the pressure sensor, monitoring the pressure sensor output for flattening during the application of the voltage pulses, and adjusting operation of the fuel system depending on whether the pressure sensor output flattens for at least a threshold duration, which is indicative of an in-range error. The method may further include dynamically learning a setpoint pressure of a pressure relief valve of the fuel system and a fuel vapor pressure within the fuel system by monitoring pressure sensor output while adjusting the duty cycle of voltage pulses applied to the lift pump.
대표청구항▼
1. A method of operating an engine fuel system, comprising: during pulsed mode operation of a lift pump, adjusting a level of voltage applied to the lift pump based on an output signal of a pressure sensor downstream of the lift pump and monitoring the output signal for flattening;in response to a d
1. A method of operating an engine fuel system, comprising: during pulsed mode operation of a lift pump, adjusting a level of voltage applied to the lift pump based on an output signal of a pressure sensor downstream of the lift pump and monitoring the output signal for flattening;in response to a detection of flattening, indicating a pressure sensor error and operating the lift pump independent of the output signal of the pressure sensor. 2. The method of claim 1, wherein monitoring the output signal for flattening comprises comparing a duration of time during which a slope of the output signal is zero to a threshold duration. 3. The method of claim 2, wherein operating the lift pump independent of the output signal of the pressure sensor comprises operating the lift pump in a continuous mode in which a constant non-zero voltage is applied to the lift pump. 4. The method of claim 2, wherein operating the lift pump independent of the output signal of the pressure sensor comprises operating the lift pump in a pulsed mode in which the level of voltage applied to the lift pump is not adjusted based on the output signal of the pressure sensor. 5. The method of claim 1, wherein adjusting the level of voltage applied to the lift pump based on the output signal of the pressure sensor comprises adjusting a duty cycle of the voltage pulses based on the output signal. 6. The method of claim 5, wherein adjusting the duty cycle of the voltage pulses based on the output signal comprises increasing the duty cycle when a peak pressure of the output signal is less than a desired peak pressure, and decreasing the duty cycle when the peak pressure is greater than the desired peak pressure. 7. The method of claim 1, wherein adjusting the level of voltage applied to the lift pump based on the output signal of the pressure sensor comprises applying a first, higher voltage to the lift pump when the output signal of the pressure sensor decreases to a desired trough pressure and applying a second, lower voltage to the lift pump when the output signal of the pressure sensor increases to a desired peak pressure. 8. The method of claim 2, wherein the pressure sensor error is an in-range error, the method further comprising, in response to the output signal increasing above or decreasing below an expected operating range of the pressure sensor, indicating an out-of-range error of the pressure sensor and operating the lift pump independent of the output signal of the pressure sensor. 9. A method for operating an engine fuel system, comprising: during steady state engine operation with a requested delivery pressure of a fuel lift pump below a first threshold, decreasing a duty cycle of voltage pulses applied to a fuel lift pump until flattening of an output signal of a pressure sensor downstream of the lift pump is detected, storing the pressure at which the output signal flattened as a fuel vapor pressure of the fuel system;during steady state engine operation with a requested delivery pressure of the fuel lift pump above a second threshold, increasing a duty cycle of voltage pulses applied to the lift pump until flattening of the output signal of the pressure sensor is detected, and storing the pressure at which the output signal flattened as a setpoint pressure of a pressure relief valve; andadjusting lift pump operation based on the stored setpoint pressure and fuel vapor pressure. 10. The method of claim 9, wherein adjusting lift pump operation based on the stored setpoint pressure and fuel vapor pressure comprises adjusting a desired peak delivery pressure of the lift pump to be less than the stored setpoint pressure by a first predetermined amount and adjusting a desired trough pressure of the lift pump to be greater than the stored fuel vapor pressure by a second predetermined amount. 11. The method of claim 10, wherein adjusting operation of the lift pump based on the stored setpoint pressure and fuel vapor pressure further comprises, during operation of the lift pump in a pulsed mode, applying a first, higher voltage to the lift pump every time the output signal of the pressure sensor decreases to the desired trough pressure and applying a second, lower voltage to the lift pump every time the output signal of the pressure sensor increases to the desired peak pressure. 12. The method of claim 10, wherein adjusting lift pump operation based on the stored setpoint pressure and fuel vapor pressure comprises determining a duty cycle of voltage pulses which, when applied to the lift pump, will produce an output signal having a maximum value at the desired peak delivery pressure and a minimum value at the desired trough delivery pressure, and applying voltage pulses to the lift pump with the determined duty cycle. 13. The method of claim 9, wherein the requested delivery pressure of the fuel lift pump is directly proportional to engine load. 14. The method of claim 12, further comprising, while applying voltage pulses to the lift pump with the determined duty cycle, monitoring the output signal of the pressure sensor for flattening, and in response to a detection of flattening, indicating a pressure sensor error and operating the lift pump independent of the output signal of the pressure sensor. 15. The method of claim 14, wherein operating the lift pump independent of the output signal of the pressure sensor comprises operating the lift pump in a continuous mode in which a constant non-zero voltage is applied to the lift pump or operating the lift pump in a pulsed mode in which the voltage pulses applied to the lift pump are not adjusted based on the output signal of the pressure sensor. 16. A hybrid vehicle, comprising: a powertrain comprising an engine, a motor/generator, a battery, and a transmission coupled to vehicle wheels;a fuel system comprising a fuel tank, a fuel lift pump, a pressure sensor arranged downstream of an output of the lift pump in the fuel system, and a pressure relief valve;a controller including non-transitory memory with instructions stored therein which are executable by a processor to:in response to a request to dynamically learn a fuel vapor pressure of the fuel system during pulsed operation of the lift pump with requested vehicle wheel torque above a first threshold, mechanically couple a crankshaft of the engine to the motor/generator, decrease engine load until an output signal of the pressure sensor remains constant for at least a first threshold duration while converting electrical energy to torque with the motor/generator and providing the torque the vehicle wheels, and store the pressure at which the output signal remains constant as the fuel vapor pressure. 17. The hybrid vehicle of claim 16, wherein the controller further comprises instructions stored in non-transitory memory and executable by a processor to: in response to a request to dynamically learn a setpoint pressure of the pressure relief valve during pulsed operation of the lift pump with requested engine output torque below a second threshold, mechanically couple the crankshaft to the motor/generator, increase engine load until the output signal of the pressure sensor remains constant for at least a second threshold duration while converting a portion of engine output torque to electrical energy with the motor/generator and storing the electrical energy at the battery, and store the pressure at which the output signal remains constant as the setpoint pressure. 18. The hybrid vehicle of claim 17, wherein the controller further comprises instructions stored in non-transitory memory and executable by a processor to: while performing closed-loop control of the lift pump based on an output signal of the pressure sensor, monitor the output signal;in response to the output signal remaining constant for at least a threshold duration, indicate an in-range error of the pressure sensor and switch from closed-loop to open-loop control of the lift pump in which lift pump operation is adjusted independent of the output signal of the pressure sensor. 19. The hybrid vehicle of claim 18, wherein the instructions stored in non-transitory memory and executable by the processor to switch from closed-loop to open-loop control of the lift pump in which lift pump operation is adjusted independent of the output signal of the pressure sensor comprise instructions to apply a continuous non-zero voltage to the lift pump. 20. The hybrid vehicle of claim 16, wherein the controller further comprises instructions stored in non-transitory memory and executable by a processor to, after storing the pressure at which the output signal remains constant as the fuel vapor pressure, adjust a duty cycle of voltage pulses applied to the lift pump based on a desired pressure margin between the fuel vapor pressure and lift pump delivery pressure.
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이 특허에 인용된 특허 (3)
Dusa, Daniel; Thomas, Joseph Lyle; Surnilla, Gopichandra; Ulrey, Joseph Norman; Pursifull, Ross Dykstra, Addressing fuel pressure uncertainty during startup of a direct injection engine.
Stavnheim, Jonathan A.; West, Stephen; Raghunathan, Shyamala, Apparatus for diagnosing failures and fault conditions in a fuel system of an internal combustion engine.
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