| US 7,467,033 B2 | ||
| Control method for a vehicle powertrain with protection against low load conditions | ||
| Kenneth Miller, Canton, Mich. (US); Paul Gartner, Dearborn, Mich. (US); Carol Okubo, Belleville, Mich. (US); Douglas Martin, Canton, Mich. (US); and Edward Badillo, Canton, Mich. (US) | ||
| Assigned to Ford Global Technologies, LLC, Dearborn, Mich. (US) | ||
| Filed on Mar. 07, 2005, as Appl. No. 10/906,784. | ||
| Prior Publication US 2006/0199695 A1, Sep. 07, 2006 | ||
| Int. Cl. B60L 9/00 (2006.01) | ||
| U.S. Cl. 701—22 [701/84; 701/101; 477/2] | 26 Claims |
| 1. A method for controlling an engine in a powertrain for a hybrid electric vehicle, the vehicle having an internal combustion
engine, at least one electric motor-generator, a battery, the battery and the motor-generator being electrically coupled,
gearing establishing power flow paths from the engine and the motor-generator to a driven member connected drivably to vehicle
traction wheels, and a controller for coordinating power distribution from the engine and the motor-generator in accordance
with operating variables including a driver demand for power and battery state of charge, the method comprising the steps
of:
calibrating a minimum load for the engine below which the engine fuel combustion tends to be unstable at a given engine speed;
determining an engine torque command by the vehicle system controller;
measuring engine load corresponding to the engine torque command;
calculating a minimum torque adder;
comparing the engine torque command at a given engine speed with a minimum engine torque that corresponds to the calibrated
minimum engine load; and
adding the minimum torque adder to the minimum engine torque when the measured engine load is near the calibrated minimum
load whereby engine fuel combustion stability is maintained.
|