Control system for a hybrid electric vehicle to anticipate the need for a mode change

1. A control system for a hybrid electric vehicle with a powertrain having a throttle-controlled internal combustion engine, the vehicle including brake pedal-controlled vehicle wheel brakes and an accelerator pedal-controlled engine throttle, the control system including accelerator pedal and brake pedal driver inputs, an electric motor/generator drive unit, a disconnect clutch between the engine and the drive unit, a power transmission between the drive unit and vehicle traction wheels, and a battery electrically connected to the drive unit for powering the same, the control system comprising:

an electronic controller including an engine speed and torque control and a drive unit speed and torque control whereby engine torque and engine on and off states are controlled;

the drive unit having a speed and torque first operating zone characterized by high efficiency drive unit torque delivery to the transmission with the engine turned off, the engine having a speed and torque second operating zone characterized by high efficiency engine torque delivery with the drive unit turned off;

means for anticipating an instant when a limit of the speed and torque first operating zone for the drive unit is reached whereby the engine is started at a pre-calculated time before the speed and torque second operating zone is entered, thereby effecting smooth power transition from the speed and torque first operating zone to the speed and torque second operating zone;

the control system including accelerator pedal and brake pedal drivers input, the control system including also means for measuring a rate of change of accelerator pedal position; and

means for responding to a measured rate of change of accelerator pedal position whereby the engine is started at a calculated time before a limit for the speed and torque first operating zone is reached.

2. A control system for a hybrid electric vehicle having pedal-operated wheel brakes and a powertrain having a throttle-controlled internal combustion engine, an electric motor/generator drive unit, a disconnect clutch between the engine and the drive unit, a power transmission between the drive unit and vehicle traction wheels and a battery electrically connected to the drive unit for powering the drive wait, the control system comprising:

an electronic controller including an engine speed and torque control and a drive unit speed and torque control whereby engine torque and engine on and off states and drive unit torque and drive unit on and off states are controlled;

the drive unit having a speed and torque first operating zone characterized by high efficiency drive unit torque delivery to the transmission with the engine turned off, the engine having a speed and torque second operating zone characterized by high efficiency engine torque delivery with the drive unit turned off, and means for anticipating an instant when a limit of one speed and torque operating zone is reached as the other operating zone is entered whereby a smooth power transition is made between the operating zones;

the control system including a throttle actuating accelerator pedal driver input and brake pedal driver input and means for measuring rate of change of brake pedal force;

the control system responding to a measured rate of change of brake pedal force whereby the engine is started at a calculated time relative to a limit of the speed and torque first operating zone with the powertrain operating in the speed and torque first operating zone and whereby the drive unit is started at a calibrated time relative to a limit of the speed and torque second operating zone with die powertrain operating in the speed and torque second operating zone.

3. A control system for a hybrid electric vehicle powertrain having a throttle-controlled internal combustion engine, the vehicle having brake pedal-controlled vehicle wheel brakes, an electric motor/generator drive unit, a disconnect clutch between the engine and the drive unit, a power transmission between the drive unit and vehicle traction wheels and a battery electrically connected to the drive unit for powering the drive unit, the control system comprising:

an electronic controller including an engine speed and torque control and a drive unit speed and torque control whereby engine torque and engine on and off states and drive unit torque and drive unit on and off states are controlled;

the drive unit having a speed and torque first operating zone characterized by high efficiency drive unit torque delivery to the transmission with the engine turned off, the engine having a speed and torque second operating zone characterized by high efficiency engine torque delivery with the drive unit turned off; and

means for anticipating an instant when a limit of one of the first and second speed and torque operating zones is reached as the other of the first and second speed and torque operating zones is entered whereby a smooth power transition is made between the first and second speed and torque operating zones;

the engine having an accelerator pedal controlled throttle and the electronic controller responding to powertrain operating variables including rate of change of accelerator pedal position.

4. A method for controlling a hybrid electric vehicle powertrain having a throttle-controlled internal combustion engine, an electric motor/generator drive unit and a disconnect clutch between the engine and the drive unit, a power transmission between the drive unit and vehicle traction wheels, a driver operated brake pedal for controlling regenerative drive unit braking and a battery electrically connected to the drive unit for powering the same, the method comprising the steps of:

controlling engine speed and torque and drive unit speed and torque in response to engine throttle position whereby speed and torque values for the drive unit are within a first operating zone corresponding to high efficiency of the drive unit and speed and torque values for the engine are within a second operating zone corresponding to high efficiency of the engine;

operating the drive unit in the first operating zone with the engine off;

operating the engine in the second operating zone with the drive unit off;

establishing regenerative drive unit braking in a regenerative braking operating zone in response to driver operated brake pedal force;

anticipating, upon changes in speed and torque, as brake pedal force changes, a torque limit of the regenerative braking operating zone whereby the engine throttle is adjusted toward a closed engine throttle and the disconnect clutch is engaged to condition the engine for developing braking torque a pre-calibrated time before the regenerative braking operation zone torque limit for the drive unit is achieved.

5. A control system for a hybrid electric vehicle with a powertrain having a throttle-controlled internal combustion engine, an electric motor/generator drive unit and a disconnect clutch between the engine and the drive unit, a power transmission between the drive unit and vehicle traction wheels, and a battery electrically connected to the drive unit for powering the same, the control system comprising:

an electronic controller including an engine speed and torque control and a drive unit speed and torque control whereby engine torque and engine on and off states are controlled;

the drive unit having a speed and torque first operating zone characterized by high efficiency drive unit torque delivery to the transmission with the engine turned off, the engine having a speed and torque second operating zone characterized by high efficiency engine torque delivery with the drive unit turned off;

the engine and the drive unit having an intermediate region of speed and torque operating conditions in which the drive unit operates with reduced efficiency and in which the engine may be started outside of the second operating zone to develop driving torque at the traction wheels while the powertrain operates in the intermediate region; and

means for anticipating an instant when a limit of the speed and torque first operating zone for the drive unit is reached whereby the engine is started at a pre-calculated time before the speed and torque second operating zone is entered, thereby effecting a smooth power transition from the speed and torque first operating zone to the speed and torque second operating zone;

the vehicle including an accelerator controlled engine throttle, the control system including an accelerator pedal for effecting engine throttle driver input and means for measuring rate of change of accelerator pedal position, the control system including also means for responding to a measured rate of change of accelerator pedal position whereby the engine is started at a calibrated time before the speed and torque second operating zone is reached.

6. A control system for a hybrid electric vehicle with a powertrain having a throttle-controlled internal combustion engine, an electric motor/generator drive unit and a disconnect clutch between the engine and the drive unit, a power transmission between the drive unit and vehicle traction wheels and a battery electrically connected to the drive unit for powering the drive unit, the control system comprising:

an electronic controller including an engine speed and torque control and a drive unit speed and torque control whereby engine torque and engine on and off states and drive unit torque and drive unit on and off states are controlled;

the drive unit having a speed and torque first operating zone characterized by high efficiency drive unit torque delivery to the transmission with the engine turned off, the engine having a speed and torque second operating zone characterized by high efficiency engine torque delivery with the drive unit turned off;

the engine and the drive unit having an intermediate speed and torque operating region wherein the drive unit operates with reduced efficiency and the engine may be started outside of the speed and torque second operating zone to develop driving torque at the wheels; and

means for anticipating an instant when a limit of one of the first and second speed and torque operating zones is reached as the other of the first and second speed and torque operating zones is entered whereby a smooth power transition is made between the first and second speed and torque operating zones;

the vehicle including brake pedal-controlled vehicle wheels brakes, the control system including a brake pedal driver input, the control system responding to a rate of change of brake pedal force whereby the engine is started at a calibrated time within the intermediate speed and torque operating region.

7. A control system for a hybrid electric vehicle with a powertrain having a throttle-controlled internal combustion engine, an electric motor/generator drive unit and a disconnect clutch between the engine and the drive unit, a power transmission between the drive unit and vehicle traction wheels and a battery electrically connected to the drive unit for powering the drive unit, the control system comprising:

an electronic controller including an engine speed and torque control and a drive unit speed and torque control whereby engine torque and engine on and off states and drive unit torque and drive unit on and off states are controlled;

the drive unit having a speed and torque first operating zone characterized by high efficiency drive unit torque delivery to the transmission with the engine turned off, the engine having a speed and torque second operating zone characterized by high efficiency engine torque delivery with the drive unit turned off;

the engine and the drive unit having an intermediate speed and torque operating region wherein the drive unit operates with reduced efficiency and the engine may be started outside of the second speed and torque operating zone to develop driving torque at the wheels; and

means for anticipating an instant when a limit of one the first and second speed and torque operating zones is reached as the other of the first and second speed and torque operating zones is entered whereby a smooth power transition is made between the speed and torque operating zones;

the vehicle including brake pedal-controlled vehicle wheels brakes, the control system including a brake pedal driver input, the control system responding to a rare of change of brake pedal force whereby the engine is started at a calibrated time within the intermediate speed and torque operating region;

the engine having an accelerator pedal controlled throttle and the electronic controller responding to powertrain operating variables including rate of change of accelerator pedal position.

8. A control system for a hybrid electric vehicle powertrain having a throttle-controlled internal combustion engine, an electric motor/generator drive unit and a disconnect clutch between the engine and the drive unit, a power transmission between the drive unit and vehicle traction wheels and a battery electrically connected to the drive unit for powering the drive unit, the control system comprising:

an electronic controller including an engine speed and torque control, a drive unit speed and torque control and means for determining vehicle acceleration whereby engine torque and engine on and off states and drive unit torque and drive unit on and off states are controlled;

the drive unit having a speed and torque first operating zone characterized by high efficiency drive unit torque delivery to the transmission with the engine turned off, the engine having a speed and torque second operating zone characterized by high efficiency engine torque delivery with the drive unit turned off;

the engine and the drive unit having an intermediate speed and torque operating region wherein the drive unit operates with reduced efficiency and the engine may be started outside of the speed and torque second operating zone to develop driving torque at the wheels; and

means for anticipating an instant when a limit of one speed and torque operating zone is reached as the other speed and torque operating zone is entered whereby a smooth power transition is made between the speed and torque operating zones;

the vehicle including brake pedal-controlled vehicle wheel brakes, the control system including a brake pedal driver input, the control system responding to a rate of change of brake pedal force whereby the engine is started at a calibrated time before a limit of the intermediate operating region is reached with the powertrain operating in the intermediate operating region;

the electronic controller responding to powertrain operating variables including rate of change of brake pedal position and vehicle acceleration.

9. A control system for a hybrid electric vehicle powertrain having a throttle-controlled internal combustion engine, the vehicle having brake pedal-controlled vehicle wheel brakes, an electric motor/generator drive unit, a disconnect clutch between the engine and the drive unit, a power transmission between the drive unit and vehicle traction wheels and a battery electrically connected to the drive unit for powering the drive unit, the control system comprising:

an electronic controller including an engine speed and torque control, a drive unit speed and torque control and means for determining vehicle acceleration whereby engine torque and engine on and off states and drive unit torque and drive unit on and off states are controlled;

the drive unit having a speed and torque first operating zone characterized by high efficiency drive unit torque delivery to the transmission with the engine turned off, the engine having a speed and torque second operating zone characterized by high efficiency engine torque delivery with the drive unit turned off, and means for anticipating an instant when a limit of one of the first and second engine speed and torque operating zones is reached as the other of the first and second speed and torque operating zones is entered whereby a smooth power transition is made between the speed and torque operating zones;

the engine having an accelerator pedal controlled throttle and the electronic controller responding to powertrain operating variables including rate of change of accelerator pedal position and vehicle acceleration.