Traction control system for a hybrid electric vehicle

Details Traction control system for a hybrid electric vehicle Traction control system for a hybrid electric vehicle

2000-05-09

2001-07-17

Cuchlinski, Jr., William A. (Department: 3661)

Data processing: vehicles, navigation, and relative location

Vehicle control, guidance, operation, or indication

Electric vehicle

C180S065230

Reexamination Certificate

active

06263267

ABSTRACT:

TECHNICAL FIELD
The present invention relates generally to automotive torque control systems and, more particularly, to traction control system for a hybrid electric vehicle.
BACKGROUND ART
Many production vehicles are equipped with traction control. Traction control prevents excessive drive wheel spin and therefore increases the stability and performance of the vehicle without compensation from the driver. Since wheel spin is due to a greater torque being applied to the wheels than the tractive limit of the tires for the given set of road conditions, a traction control event reduces the torque applied to the wheels.
Torque reduction is typically done by applying the brakes to the wheel or wheels that are spinning, as well as reducing the engine torque being applied. The engine torque reduction can be done several ways in a conventional vehicle: spark timing retard, fuel cutoff, and engine throttle. Of these alternatives, engine throttle is the most attractive when considering tailpipe emissions, fuel economy, NVH, and driver feel.
Unfortunately, engine transients, even with optimum AFR and spark timing, are a major contributor to tail pipe emissions due to physical and control time delays. Additionally, the engine must operate at less then an optimum condition during these traction control events. Also, in a conventional vehicle, the torque reduction due to each actuator must be calculated to determine the total torque reduction necessary from the engine. These calculations introduce errors and time to perform tasks may introduce significant wheel torque errors.
The disadvantages associated with this conventional torque control technique have made it apparent that a new technique for traction control for a hybrid electric vehicle is needed. Preferably, the new technique would allow the engine to continue operating at its optimum level during traction control events without negatively affecting tailpipe emissions, NVH or fuel economy.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved and reliable means for traction control for a hybrid electric vehicle. Another object of the invention is to allow the engine to continue operating at an optimum level during traction control events.
In accordance with the objects of this invention, a traction control system for a hybrid electric vehicle is provided. In one aspect of the invention, an electric motor system for reducing drive wheel torque on a hybrid electric vehicle includes an internal combustion engine, an electric motor, a transmission, and a controller. The internal combustion engine is located in the hybrid electric vehicle and generates an engine torque. The electric motor is coupled to the internal combustion engine and generates an electric motor torque. Both the engine and motor are coupled to the transmission that uses the combined torque from both the engine and motor to generate drive wheel torque on a drive wheel. The vehicle system controller is coupled to the electric motor and senses any traction control events. When a traction control event occurs the controller commands the electric motor to reduce the drive wheel torque by reducing the electric motor torque.
The present invention achieves an improved and reliable means for traction control for a hybrid electric vehicle. Also, the present invention is advantageous in that it reduces the amount of software code required to implement a traction control strategy.
Additional advantages and features of the present invention will become apparent from the description that follows, and may be realized by means of the instrumentalities and combinations particularly pointed out in the appended claims, taken in conjunction with the accompanying drawings.


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patent: 5839533 (1998-11-01), Mikami et al.
patent: 5951614 (1999-09-01), Tabata et al.
patent: 5954779 (1999-09-01), Dietzel
patent: 5984033 (1999-11-01), Tamagawa et al.
patent: 6026921 (2000-02-01), Aoyama et al.

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