Method for controlling starting of an engine in a hybrid electric vehicle powertrain

• US 7,013,213 B2
• Filed: 05/12/2004
• Issued: 03/14/2006
• Est. Priority Date: 05/12/2004
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Kuang, Ming, Syed, Fazal, McGee, Ryan, Czubay, John, Niessen, Paul, Butcher, Jonathan
• Primary Examiner(s): Argenbright, Tony M.
• Assistant Examiner(s): Hoang, Johnny H.
• Application Number:
  US10/709,537
• Publication Number:
  US 20050256632A1
• Time in Patent Office: 671 Days
• Field of Search: 701/113, 701/111, 180/65.2, 123/179.3, 123/179.4
• US Class Current: 701/113
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60K 6/448 Electrical distribution type
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 30/18027 Drive off, accelerating from standstill
• CPC Class Codes: F02N 11/00 Starting of engines by means of electric motors
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A method for controlling starting of an internal combustion engine in a hybrid electric vehicle powertrain having multiple power flow paths to vehicle traction wheels from the engine and from an electric motor. A smoothness factor is calculated to determine how smooth an engine start should be. Engine operating variables regulate engine smoothness during engine start events as determined by the calculated smoothness factor appropriate for selected vehicle operating conditions.

Claims

1. A method for determining an engine smoothness factor during an engine start event for an internal combustion engine in a vehicle having a hybrid powertrain that includes also an electric motor, a battery, a generator and transmission torque delivery elements that define, in part, power flow paths from the engine and the motor to vehicle traction wheels whereby the engine may be turned off during power delivery from the electric motor, the method comprising the steps of:

determining a first powertrain operating condition indicating whether the vehicle is in a park mode or a neutral mode and initializing the method by determining a temporary smoothness factor depending on park or neutral selection and setting it to a value corresponding to maximum smoothness if the vehicle is in a park mode or a neutral mode;

determining at least one of multiple additional powertrain operating conditions;

determining empirically at least one additional temporary smoothness factor as a function of the at least one of multiple powertrain operating conditions;

each additional temporary smoothness factor having a value indicating smoothness between maximum and minimum smoothness; and

selecting the determined temporary smoothness factor having a value corresponding to least smoothness when the engine is in a start-up mode.

2. The method set forth in claim 1 wherein the additional powertrain operating conditions include ambient temperature, low battery discharge power limit and low battery voltage.

3. A method for determining an engine smoothness factor during an engine start event for an internal combustion engine in a vehicle having a hybrid powertrain that includes also an electric motor, a battery, a generator and transmission torque delivery elements that define, in part, power flow paths from the engine and the motor to vehicle traction wheels whereby the engine may be turned off during power delivery from the electric motor, the method comprising the steps of:

determining a first powertrain operating condition indicating whether the vehicle is in a park mode or a neutral mode and initializing the method by determining a temporary smoothness factor depending on park or neutral selection and setting it to a value corresponding to maximum smoothness if the vehicle is in a park mode or a neutral mode;

determining at least one of multiple additional powertrain operating conditions;

determining empirically at least one additional temporary smoothness factor as a function of the at least one of multiple powertrain operating conditions;

each additional temporary smoothness factor having a value indicating smoothness between maximum and minimum smoothness;

selecting the determined temporary smoothness factor having a value corresponding to least smoothness when the engine is in a start-up mode; and

adjusting engine start smoothness using at least one engine operating variable selected from multiple engine operating variables, selection of the at least one engine operating variable being determined by a calibrated relationship of the temporary smoothness factor and each selected engine operating variable.

4. The method set forth in claim 3 wherein the additional powertrain operating conditions include ambient temperature, low battery discharge power limit and low battery voltage.

5. A method for determining an engine smoothness factor in an engine start event for an engine in a vehicle having a hybrid powertrain that includes an electric motor and transmission torque delivery elements that define, in part, integrated power flow paths to vehicle traction wheels whereby the engine is turned off during power delivery from the electric motor, the method comprising the steps of:

determining whether the vehicle is in a park mode or a neutral mode and initializing the method by determining a temporary smoothness factor depending on park or neutral selection and setting it to a value corresponding to maximum smoothness if the vehicle is in a park mode or a neutral mode;

measuring battery voltage and determining a temporary smoothness factor as a function of battery voltage and setting it to a value corresponding to reduced smoothness if battery voltage is less than a calibrated voltage value;

measuring engine coolant temperature and determining a temporary smoothness factor as a function of engine coolant temperature;

determining battery discharge power limit and determining a temporary smoothness factor as a function of the battery discharge power limit; and

selecting the determined temporary smoothness factor with a value corresponding to least smoothness and latching it at that value when the engine is in a start-up mode.

6. A method for determining an engine smoothness factor in an engine start event for an engine in a vehicle having a hybrid powertrain that includes an electric motor and transmission torque delivery elements that define, in part, integrated power flow paths to vehicle traction wheels whereby the engine is turned off during power delivery from the electric motor, the method comprising the steps of:

determining whether the vehicle is in a park mode or a neutral mode and initializing the method by determining a temporary smoothness factor depending on park or neutral selection and setting it to a value corresponding to maximum smoothness if the vehicle is in a park mode or a neutral mode;

measuring battery voltage and determining a temporary smoothness factor as a function of battery voltage and setting it to a value corresponding to reduced smoothness if battery voltage is less than a calibrated voltage value;

measuring engine coolant temperature and determining a temporary smoothness factor as a function of engine coolant temperature;

determining a temporary smoothness factor as a function of a battery discharge power limit;

selecting the determined temporary smoothness factor with a value corresponding to least smoothness and latching it at that value when the engine is in a start-up mode; and

adjusting engine start smoothness using at least one engine operating variable selected from multiple engine operating variables, selection of the at least one engine operating variable being determined by a calibrated relationship of the latched temporary smoothness factor and each selected engine operating variable.

7. The method set forth in claim 6, wherein the selected engine operating variables include at least one of a group of variables comprising engine speed command profile, engine throttle setting, fuel injection timing, engine spark timing and engine valve timing.

8. A method for determining an engine smoothness factor in an engine start event for an engine in a vehicle having a hybrid powertrain that includes an electric motor and transmission torque delivery elements that define, in part, integrated power flow paths to vehicle traction wheels whereby the engine is turned off during power delivery from the electric motor, the method comprising the steps of:

determining whether the vehicle is in a park mode or a neutral mode, and initializing the method by determining a temporary smoothness factor depending on park or neutral selection and setting it to a value corresponding to maximum smoothness if the vehicle is in a park mode or a neutral mode;

measuring battery voltage and determining a temporary smoothness factor as a function of battery voltage;

determining battery discharge power limit and determining a temporary smoothness factor as a function of the battery discharge power limit; and

selecting the determined temporary smoothness factor with a value corresponding to least smoothness and latching it at that value when the engine is in a start-up mode.

9. A method for determining an engine smoothness factor in an engine start event for an engine in a vehicle having a hybrid powertrain that includes an electric motor and transmission torque delivery elements that define, in part, integrated power flow paths to vehicle traction wheels whereby the engine is turned off during power delivery from the electric motor, the method comprising the steps of:

determining whether the vehicle is in a park mode or a neutral mode and initializing the method by determining a temporary smoothness factor depending on park or neutral selection and setting it to a value corresponding to maximum smoothness if the vehicle is in a park mode or a neutral mode;

measuring engine coolant temperature and determining a temporary smoothness factor as a function of engine coolant temperature;

determining a temporary smoothness factor as a function of the battery discharge power limit;

selecting the determined temporary smoothness factor with a value corresponding to least smoothness and latching it at that value when the engine is in a start-up mode; and

adjusting engine start smoothness using at least one engine operating variable selected from multiple engine operating variables, selection of the at least one engine operating variable being determined by a calibrated relationship of the latched temporary smoothness factor and each selected engine operating variable.