HYBRID ELECTRIC VEHICLE CONTROL STRATEGY TO PROVIDE VEHICLE CREEP AND HILL HOLDING

• US 20030085576A1
• Filed: 11/08/2001
• Published: 05/08/2003
• Est. Priority Date: 11/08/2001
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Kuang, Ming Lang, Breida, Mary Theresa
• Granted Patent: US 6,590,299 B2
• Time in Patent Office: Days
• US Class Current: 290/40C
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/425 Temperature
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 2260/22 Standstill, e.g. zero speed
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• 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 20/11 using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance utilising navigation and traffic information in the control strategy B60W20/12
• CPC Class Codes: B60W 20/30 Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 2510/087 Temperature
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/12 : Brake pedal position
• CPC Class Codes: B60W 2540/16 : Ratio selector position
• CPC Class Codes: B60W 30/18063 : Creeping
• CPC Class Codes: B60W 30/1846 : Preventing of breakage of drive line components, e.g. parts of the gearing
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

The invention is a control strategy for a hybrid electric vehicle (HEV) to meet driver expectation for hill holding or creep capability found in conventional automobiles with an automatic transmission. The strategy is activated when the PRNDL is in drive or low-drive position and no accelerator applied. Alternatively, the strategy can also require no brake being applied as well. The strategy can use the traction motor, generator motor or engine to achieve creep or hill holding. The engine is used when the traction motor temperature exceeds a predefined value or the engine is already running. If the engine is not running, the strategy can determine when to start it and regulate the amount of engine torque needed to hold the vehicle on the hill using the generator motor. The invention maintains efficient engine usage and minimizes battery usage and loss.

Claims

1. A control system for a powersplit hybrid electric vehicle (HEV) powertrain powered by at least one of an engine, a traction motor, and a generator motor, comprising:

an accelerator position sensor;

a traction motor temperature sensor;

a vehicle speed sensor;

a PRNDL position sensor;

a battery for powering the traction motor and generator motor and receiving power from the generator motor; and

a vehicle system control (VSC) to control the vehicle powertrain, the VSC receiving input from the accelerator position sensor, vehicle speed sensor, traction motor temperature sensor, and PRNDL position sensor, making a determination of whether zero accelerator demand from the driver is requested,

making a determination of whether the PRNDL is in a forward drive mode,

making a determination of whether the engine is running,

making a determination of whether the vehicle is rolling backward,

making a determination of whether the traction motor exceeds a predetermined temperature threshold, and

starting the engine if the engine is off and traction motor temperature exceeds a predetermined threshold,

starting the engine if the engine is off and the vehicle is rolling backward,

commanding a traction motor torque request when the engine is off,

accelerator demand is zero, the PRNDL is in the forward drive mode, and

the vehicle is not rolling backward based on creep torque or hill holding function requirements,

commanding the engine to start and providing engine torque when the engine is off, accelerator demand is zero, the PRNDL is in the forward drive mode, and the vehicle is rolling backward based on creep torque or hill holding function requirements, and

commanding an engine torque request when the engine is running, accelerator demand is zero, and the PRNDL is in the forward drive mode based on creep torque or hill holding function requirements.

2. The control system of claim 1 further comprises a determination of brake position demand based on VSC input from a brake position sensor.

3. The control system of claim 2 wherein commanding the traction motor torque request further comprises a zero brake position demand.

4. The control system of claim 2 wherein commanding the engine torque request further comprises a zero brake position demand.

5. A method to control a powersplit hybrid electric vehicle (HEV) powertrain powered by at least one of an engine, a traction motor, and a generator motor, comprising the steps of:

sensing accelerator position;

sensing traction motor temperature;

sensing vehicle speed;

sensing PRNDL position;

powering the traction motor and generator motor and receiving power from the generator motor with a battery; and

controlling the vehicle powertrain with a vehicle system control (VSC), the VSC receiving input from the accelerator position sensor, vehicle speed sensor, traction motor temperature sensor, and PRNDL position sensor,

making a determination of whether zero accelerator demand from the driver is requested,

making a determination of whether the PRNDL is in a forward drive mode, making a determination of whether the engine is running,

making a determination of whether the vehicle is rolling backward,

making a determination of whether the traction motor exceeds a predetermined temperature threshold, and

starting the engine if the engine is off and traction motor temperature exceeds a predetermined threshold,

starting the engine if the engine is off and the vehicle is rolling backward,

commanding a traction motor torque request when the engine is off,

accelerator demand is zero, the PRNDL is in the forward drive mode, and

the vehicle is not rolling backward based on creep torque or hill holding function requirements,

commanding the engine to start and providing engine torque when the engine is off, accelerator demand is zero, the PRNDL is in the forward drive mode, and the vehicle is rolling backward based on creep torque or hill holding function requirements, and

commanding an engine torque request when the engine is running,

accelerator demand is zero, and the PRNDL is in the forward drive mode based on creep torque or hill holding function requirements.

6. The method of claim 5 further comprising the step of making a determination brake position based on VSC input from a brake position sensor.

7. The method of claim 6 wherein commanding the traction motor torque request further comprises a zero brake position.

8. The method of claim 6 wherein commanding the engine torque request further comprises a zero brake position.