Control System for a Hybrid Electric Vehicle to Anticipate the Need for a Mode Change

• US 20080224478A1
• Filed: 05/22/2008
• Published: 09/18/2008
• Est. Priority Date: 10/11/2000
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Tamor, Michael
• Granted Patent: US 7,753,150 B2
• Time in Patent Office: Days
• US Class Current: 290/40C
• CPC Class Codes: B60K 6/48 Parallel 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 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/10 Controlling the power contribution of each of the prime movers to meet required power demand
• CPC Class Codes: B60W 2050/0031 Mathematical model of the vehicle
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/105 Longitudinal acceleration
• CPC Class Codes: B60W 2530/10 Weight
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/106 Rate of change
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/903 having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/947 Characterized by control of braking, e.g. blending of regeneration, friction braking

Abstract

A parallel hybrid electric vehicle method and system including an internal combustion engine (ICE), an electric traction motor/generator, and a controller. A control strategy is provided to prevent unpredicted or undesired engine starts by anticipating the need for the vehicle engine, while avoiding “false starting” the engine or allowing an annoying lag in performance that will occur if the engine is not started in advance of an actual requirement. The invention anticipates the need for engine starts and electromotive driving by monitoring vehicle speed and driver commands and their rates of change. The invention allows consistent performance and establishes seamless transitions between engine driving and electromotive driving.

Claims

1. A method for controlling a powertrain for a hybrid electric vehicle, the vehicle having vehicle wheel brakes, the powertrain having an internal combustion engine with an accelerator pedal and a throttle controlled by a vehicle system controller that responds to accelerator pedal movement, vehicle wheel brakes, an electric motor/generator drive unit, a driver operated brake pedal for controlling regenerative drive unit braking and for applying the vehicle wheel brakes, 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, within a maximum drive unit power capability, in response to engine throttle position whereby power values for the drive unit are within a first speed and torque operating zone characterized by high efficiency drive unit power delivery and power values for the engine are within a second speed and torque operating zone characterized by high efficiency engine power delivery;

turning off the engine to effect power delivery solely by the battery;

turning off the drive unit to effect power delivery solely by the engine;

establishing regenerative drive unit braking power in a regenerative braking operating zone in response to driver operated brake pedal force and rate of change of brake pedal force;

anticipating, upon changes in speed and torque, as brake pedal force and rate of brake pedal force change, a power limit for the regenerative braking operating zone; and

applying the vehicle wheel brakes to complement regenerative braking as the regenerative braking zone power limit is approached

2. A hybrid electric vehicle with vehicle wheel brakes, a driver actuated accelerator pedal and a driver actuated brake pedal, a powertrain having an internal combustion engine with a throttle controlled by a vehicle system controller that responds to accelerator pedal driver input and to brake pedal driver input, an electric drive unit, and a battery electrically connected to the drive unit for powering the drive unit;

a powertrain control system electrically coupled to the vehicle system controller including means for turning off the engine to effect power delivery solely from the battery and means for turning on the engine to effect power delivery selectively by the engine solely and by the engine and battery working together;

the drive unit having a power delivery first operating zone characterized by high efficiency battery power delivery within a maximum battery power capability, the engine having a power delivery second operating zone characterized by high efficiency engine power delivery;

the engine and the drive unit having an intermediate operating region in which the drive unit operates with reduced efficiency and the engine may be started to develop driving torque; and

means for anticipating an instant when the maximum power capability of the battery is reached during a transition between the first and second power delivery operating zones;

the powertrain control system including a brake pedal driver input from the vehicle system controller and responding to a rate of change of brake pedal force whereby the engine is started at a calibrated time within the intermediate operating region relative to the instant when the battery power limit is reached during a transition between the power delivery operating zones.

4. The hybrid electric vehicle set forth in claim 2 wherein the power transmission comprises a planetary gear unit and the electric drive unit comprises a generator and a motor;

the planetary gear unit having a first element drivably connected to the generator, a second element drivably connected to the vehicle traction wheels and a third element drivably connected to the engine; and

the motor being drivably connected to the vehicle traction wheels.

3. A hybrid electric vehicle powertrain having an internal combustion engine with an accelerator pedal and a throttle controlled by a vehicle system controller that responds to accelerator pedal movement and vehicle brake pedal movement, an electric drive unit, a battery electrically connected to the drive unit for powering the electric drive unit;

a powertrain control system electrically coupled to the vehicle system controller including an engine speed and torque control, a drive unit speed and torque control and means for measuring rates of change of accelerator pedal position and vehicle brake pedal force whereby engine on and off states and drive unit on and off states are effected;

the drive unit having a power delivery first operating zone characterized by high efficiency drive unit power delivery within a maximum power capability, the engine having a power delivery second operating zone characterized by high efficiency engine power delivery;

the engine and the drive unit having an intermediate power delivery operating region in which the drive unit operates with reduced efficiency and the engine may be started to develop driving torque; and

means for anticipating an instant, during operation in the intermediate region, when the maximum power capability of the battery is reached whereby the engine is started to effect a smooth power transition between the power delivery operating zones;

the powertrain control system including a brake pedal driver input, the control system responding to operating variables including a rate of change of brake pedal force and a rate of change of accelerator pedal position whereby the engine is started at a calibrated time before the maximum power capability of the battery is reached with the powertrain operating in the intermediate operating region.

5. The hybrid electric vehicle set forth in claim 3 wherein the power transmission comprises a planetary gear unit and the electric drive unit comprises a generator and a motor;

the planetary gear unit having a first element drivably connected to the generator, a second element drivably connected to the vehicle traction wheels and a third element drivably connected to the engine; and

the motor being drivably connected to the vehicle traction wheels.

6. The hybrid electric vehicle set forth in claim 3 wherein the powertrain operating variables include vehicle speed and rate of vehicle acceleration.

7. The hybrid electric vehicle set forth in claim 3 wherein the powertrain operating variables include road grade.

8. A hybrid electric vehicle with vehicle wheel brakes, a powertrain having a throttle-controlled internal combustion engine with an accelerator pedal and a throttle that responds to accelerator pedal driver input, an electric drive unit, and a battery electrically connected to the drive unit for powering the drive unit;

a powertrain control system including means for turning off the engine to effect power delivery solely from the battery and means for turning on the engine to effect power delivery selectively by the engine solely and by the engine and battery working together;

the drive unit having a power delivery first operating zone characterized by high efficiency battery power delivery within a maximum battery power capability, the engine having a power delivery second operating zone characterized by high efficiency engine power delivery;

the engine and the drive unit having an intermediate operating region in which the drive unit operates with reduced efficiency and the engine may be started to develop driving torque; and

means for anticipating an instant when the maximum power capability of the battery is reached during a transition between the first and second power delivery operating zones;

the powertrain control system having a vehicle brake pedal driver input including brake pedal-controlled vehicle brakes, the powertrain control system including a brake pedal driver input and responding to a rate of change of brake pedal force whereby the engine is started at a calibrated time within the intermediate operating region relative to the instant when the battery power limit is reached during a transition between the power delivery operating zones.

10. The hybrid electric vehicle set forth in claim 8 wherein the power transmission comprises a planetary gear unit and the electric drive unit comprises a generator and a motor;

the planetary gear unit having a first element drivably connected to the generator, a second element drivably connected to the vehicle traction wheels and a third element drivably connected to the engine; and

the motor being drivably connected to the vehicle traction wheels.

9. A hybrid electric vehicle powertrain having a throttle-controlled internal combustion engine with an accelerator pedal and a throttle that responds to accelerator pedal movement and vehicle brake pedal movement, an electric drive unit, a battery electrically connected to the drive unit for powering the electric drive unit;

a powertrain control system including an engine speed and torque control, a drive unit speed and torque control and means for measuring rates of change of accelerator pedal position and vehicle brake pedal force whereby engine on and off states and drive unit on and off states are effected;

the drive unit having a power delivery first operating zone characterized by high efficiency drive unit power delivery within a maximum power capability, the engine having a power delivery second operating zone characterized by high efficiency engine power delivery;

the engine and the drive unit having an intermediate power delivery operating region in which the drive unit operates with reduced efficiency and the engine may be started to develop driving torque; and

means for anticipating an instant, during operation in the intermediate region, when the maximum power capability of the battery is reached whereby the engine is started to effect a smooth power transition between the power delivery operating zones;

the powertrain control system including a brake pedal driver input, the control system responding to operating variables including a rate of change of brake pedal force and a rate of change of accelerator pedal position whereby the engine is started at a calibrated time before the maximum power capability of the battery is reached with the powertrain operating in the intermediate operating region.

11. The hybrid electric vehicle set forth in claim 9 wherein the power transmission comprises a planetary gear unit and the electric drive unit comprises a generator and a motor;

the planetary gear unit having a first element drivably connected to the generator, a second element drivably connected to the vehicle traction wheels and a third element drivably connected to the engine; and

the motor being drivably connected to the vehicle traction wheels.

12. The hybrid electric vehicle set forth in claim 9 wherein the powertrain operating variables include vehicle speed and rate of vehicle acceleration.

13. The hybrid electric vehicle set forth in claim 9 wherein the powertrain operating variables include road grade.