DETECTING PRESSURE SENSOR OFFSET IN A PHEV FUEL TANK

• US 20150075251A1
• Filed: 09/16/2013
• Published: 03/19/2015
• Est. Priority Date: 09/16/2013
• Status: Abandoned Application

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: JENTZ, ROBERT ROY, DUDAR, AED M.
• Application Number:
  US14/027,281
• Publication Number:
  US 20150075251A1
• Time in Patent Office: Days
• US Class Current: 73/1.63
• CPC Class Codes: B60K 2015/0319 with electronic systems, e.g. for controlling fuelling or venting for LPG tanks B60K2015/03013
• CPC Class Codes: F02D 41/003 Adding fuel vapours, e.g. drawn from engine fuel reservoir
• CPC Class Codes: F02D 41/2474 Characteristics of sensors
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: G01L 19/02 Arrangements for preventing, or for compensating for, effects of inclination or acceleration of the measuring device; Zero-setting means for aneroid barometers G01L7/14
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

A method for determining pressure sensor offset values in an evaporative emission control system. The method is performed during initial vehicle power up, and the method begins by receiving a reference signal indicating existing atmospheric pressure, as well as a check signal from a fuel tank pressure sensor indicating pressure within the fuel tank, at a time when the fuel system is open to atmosphere. A controller then calculates a sensor offset value based upon the reference signal and the check signal, and the controller stores the sensor offset value in a system memory location. During operation of the evaporative emission control system, the controller modifies pressure values received from the fuel tank pressure sensor by applying the sensor offset value. Whenever the system employs a reading from the fuel tank pressure sensor, that reading is corrected by applying the stored offset value.

Claims

1. A method for determining pressure sensor offset values in an evaporative emission control system, comprising:

during initial vehicle power up,

receiving a reference signal indicating existing atmospheric pressure;

further receiving a check signal from a fuel tank pressure sensor indicating pressure within the fuel tank, at a time when the fuel system is open to atmosphere;

calculating a sensor offset value based upon the reference signal and the check signal; and

storing the sensor offset value in a system memory location;

during operation of the evaporative emission control system, modifying pressure values received from the fuel tank pressure sensor by applying the sensor offset value.

2. The method of claim 1, wherein the fuel tank pressure sensor is a Fuel Tank Pressure Transducer (FTPT).

3. The method of claim 1 further comprising a reference pressure sensor to sense the reference signal.

4. The method of claim 3 further comprising a controller connected to the pressure sensor to establish pressure values determined by the reference pressure sensor and the fuel tank pressure sensor, the controller also including the reference pressure sensor.

5. The method of claim 1 further comprising a Powertrain Control Module (PCM) receiving and storing the reference signal and the check signal.

6. The method of claim 5, wherein the PCM includes:

a calculating module to calculate the sensor offset; and

a memory where the offset value is stored.

7. The method of claim 1, wherein the reference signal is obtained either through a mechanism arranged within the vehicle;

or a mechanism arranged outside the vehicle.

8. A method for correcting a stored pressure sensor offset value in an evaporative emission control system, comprising:

determining a fuel tank pressure fall off rate, based on at least two fuel tank pressure measurements, the pressure measurements being offset by the stored pressure sensor offset value;

calculating a predicted fuel tank pressure value at a selected time, based on the fuel tank pressure fall off rate;

determining an existing fuel tank pressure value at the selected time;

calculating an actual pressure value within the fuel tank using the stored pressure offset value; and

correcting the stored pressure sensor offset value by an amount corresponding to any difference between the predicted fuel tank pressure value an actual fuel tank pressure value.

9. The method of claim 8, wherein fuel tank pressure is measured by a pressure sensor, which in turn being connected to a controller and a Powertrain Control Module (PCM), facilitates a corresponding pressure value storage within the PCM.

10. The method of claim 8, wherein predicting the fuel tank pressure value at the selected time is performed by an algorithm installed within the PCM, the PCM correcting the stored pressure sensor offset value based on the predicted fuel tank pressure value.