CVT hybrid powertrain fueling and engine stop-start control method
View Patent ↗Methods are provided for controlling the fueling of a motor vehicle and specifically for controlling the cut off of fueling of a hybrid electric motor vehicle during deceleration of that motor vehicle. In a hybrid electric motor vehicle having an internal combustion engine, a motor/generator, and a continuously variable transmission, one embodiment of the method comprises the steps of sensing throttle position of the internal combustion engine and slewing the continuously variable transmission to a higher gear ratio in response to sensing a closed throttle position. The method further comprises the steps of cutting fueling of the internal combustion engine during the deceleration, and coupling the motor/generator in parallel with the internal combustion engine with the motor/generator operating as a generator.
1. A method for controlling the fueling of a hybrid electric motor vehicle having an internal combustion engine, a motor/generator, and a continuously variable transmission, the method comprising the steps of:
sensing throttle position of the internal combustion engine;
slewing the continuously variable transmission to a higher gear ratio in response to sensing a closed throttle position;
cutting fueling of the internal combustion engine; and
coupling the motor/generator in parallel with the internal combustion engine with the motor/generator operating as a generator.
2. The method of claim 1 further comprising the step, following the step of cutting fueling, of maintaining engine RPM of the internal combustion engine constant until the motor vehicle speed decreases to a first predetermined vehicle speed.
3. The method of claim 2 further comprising the step of slewing the continuously variable transmission to a lower gear ratio when the motor vehicle speed reaches the first predetermined vehicle speed to cause the internal combustion engine to be backdriven.
4. The method of claim 1 further comprising the steps of:
monitoring speed of the motor vehicle; and
terminating the step of coupling the motor/generator in parallel with the internal combustion engine with the motor/generator operating as a generator in response to the speed of the motor vehicle decreasing to a second predetermined vehicle speed.
5. The method of claim 4 further comprising the step of coupling the motor/generator in parallel with the internal combustion engine with the motor/generator operating as a motor following the step of terminating.
6. The method of claim 5 wherein the step of coupling the motor/generator in parallel with the internal combustion engine with the motor/generator operating as a motor comprises the step of operating the motor/generator as a motor to maintain the internal combustion engine RPM substantially constant.
7. The method of claim 6 wherein the hybrid electric vehicle further comprises a battery pack coupled to the motor/generator and wherein the method further comprises the steps of:
monitoring the battery pack state of charge; and
controlling the motor/generator operating as a motor as a function of the monitored state of charge.
8. The method of claim 7 wherein the step of controlling the motor/generator operating as a motor comprises the step of controlling the motor/generator to cause the motor vehicle speed to decrease to zero without refueling the internal combustion engine.
9. The method of claim 1 wherein the hybrid electric vehicle further comprises a battery pack coupled to the motor/generator and wherein the method further comprises the steps of:
monitoring the battery pack state of charge; and
controlling the motor/generator operating as a generator as a function of the monitored state of charge.
10. The method of claim 9 wherein the step of controlling comprises the step of controlling the step of slewing the continuously variable transmission.
11. The method of claim 9 wherein the hybrid electric vehicle further comprises an air conditioning compressor and wherein the step of controlling further comprises the step of controlling the motor/generator operating as a generator as a function of air conditioner compressor load.