초록 ▼

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. Alternativel

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 strategy maintains efficient engine usage and minimizes battery usage and loss.

대표청구항 ▼

What is claimed is: 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 positi

What is claimed is: 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 dive 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 id="INS-S-00001" date="20080325" of id="INS-S-00001" 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. id="INS-S-00002" date="20080325" 9. A control system for a vehicle having an electric motor, and an engine, the motor and engine each being operable to provide torque to propel the vehicle, the system comprising: a temperature sensor for sensing a temperature of the electric motor; and a controller configured to receive signals from the temperature sensor and to determine when a creep or holding torque is desired, the controller being further configured to effect starting of the engine when the engine is off, it is determined that a creep or holding torque is desired, and the sensed temperature of the motor exceeds a predetermined threshold.id="INS-S-00002" id="INS-S-00003" date="20080325" 10. The control system of claim 9, wherein the controller is further configured to command an engine torque request based on creep or holding torque requirements when the engine is running and it is determined that a creep or holding torque is required.id="INS-S-00003" id="INS-S-00004" date="20080325" 11. The control system of claim 9, the vehicle further having a transmission, the control system further comprising a gear sensor for sensing a current gear of the transmission and for outputting signals related to the sensed gear to the controller, and wherein the controller is further configured to determine when the vehicle is moving backward, and to effect starting of the engine when the engine is off, the vehicle is moving backward, and the current gear is a forward gear.id="INS-S-00004" id="INS-S-00005" date="20080325" 12. The control system of claim 11, wherein the determination of when the vehicle is moving backward is at least partly based on the signals received from the gear sensor and a direction of rotation of the motor.id="INS-S-00005" id="INS-S-00006" date="20080325" 13. The control system of claim 11, wherein the controller is further configured to command a motor torque request based on creep or holding torque requirements when the engine is off, the vehicle is not moving backward, and the sensed temperature of the motor does not exceed the predetermined threshold.id="INS-S-00006" id="INS-S-00007" date="20080325" 14. The control system of claim 11, the vehicle further having an accelerator, the control system further comprising an accelerator position sensor for sensing a position of the accelerator and for outputting signals to the controller related to the sensed accelerator position, and wherein the determination of when a creep or holding torque is desired is at least partly based on the accelerator position and the current gear of the transmission.id="INS-S-00007" id="INS-S-00008" date="20080325" 15. A control system for a vehicle having brakes, a transmission, an electric motor, and an engine, the motor and engine each being operable to provide torque to propel the vehicle, the system comprising: a gear sensor for sensing a current gear of the transmission; a temperature sensor for sensing a temperature of the motor; a brake position sensor for sensing a position of the brakes; and a controller configured to receive signals from the gear sensor, the temperature sensor, and the brake position sensor, and to determine when the vehicle is moving backward, the controller being further configured to effect starting of the engine when the engine is off, the vehicle is moving backward, the brake position is zero, and the current gear is a forward gear, the controller is further configured to determine when a creep or holding torque is desired, and to effect starting of the engine when the engine is off, it is determined that a creep or holding torque is desired, and the sensed temperature of the motor exceeds a predetermined threshold.id="INS-S-00008" id="INS-S-00009" date="20080325" 16. The control system of claim 15, wherein the determination of when the vehicle is moving backward is at least partly bawed on the signals received from the gear sensor and a direction of rotation of the motor.id="INS-S-00009" id="INS-S-00010" date="20080325" 17. The control system of claim 15, wherein the controller is further configured to command a motor torque request based on creep or holding torque requirements when the engine is off, the vehicle is not moving backward, and the sensed temperature of the motor does not exceed the predetermined threshold.id="INS-S-00010" id="INS-S-00011" date="20080325" 18. The control system of claim 15, the vehicle further having an accelerator, the control system further comprising an accelerator position sensor for sensing a position of the accelerator and for outputting signals to the controller related to the sensed accelerator position, and wherein the controller is further configured to determine when a creep or holding torque is desired at least partly based on the accelerator position and the current gear of the transmission.id="INS-S-00011" id="INS-S-00012" date="20080325" 19. The control system of claim 15, wherein the controller is further configured to determine when a creep or holding torque is desired, and to command an engine torque request based on creep or holding torque requirements when the engine is running and it is determined that a creep or holding torque is required.id="INS-S-00012" id="INS-S-00013" date="20080325" 20. A method for controlling a vehicle having an electric motor, and an engine, the motor and engine each being operable to provide torque to propel the vehicle, the method comprising: sensing a temperature of the electric motor; determining when a creep or holding torque is desired; and effecting a starting of the engine when the engine is off, it is determined that a creep or holding torque is desired, and the sensed temperature of the motor exceeds a predetermined threshold.id="INS-S-00013" id="INS-S-00014" date="20080325" 21. The method of claim 20, further comprising commanding an engine torque request based on creep or holding torque requirements when the engine is running and it is determined that a creep or holding torque is required.id="INS-S-00014" id="INS-S-00015" date="20080325" 22. The method of claim 20, the vehicle further having a transmission, the method further comprising: sensing a current gear of the transmission; determining when the vehicle is moving backward; and effecting a starting of the engine when the engine is off, the vehicle is moving backward, and the current gear is a forward gear.id="INS-S-00015" id="INS-S-00016" date="20080325" 23. The method of claim 20, further comprising commanding a motor torque request based on creep or holding torque requirements when the engine is off, the vehicle is not moving backward, and the sensed temperature of the motor does not exceed the predetermined threshold.id="INS-S-00016"