Electronic throttle control

Details Electronic throttle control Electronic throttle control

2000-03-31

2001-09-18

Solis, Erick (Department: 3747)

Internal-combustion engines

Engine speed regulator

Open loop condition responsive

C123S361000

Reexamination Certificate

active

06289874

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a throttle body and control system for a vehicle. More specifically the present invention relates to a control method and apparatus for controlling the position of a throttle plate in a throttle body.
Electronic engine control has evolved from a relatively elementary control system employing simple switches and analog devices to a highly precise fuel and ignition control system employing powerful microprocessors or microcontrollers. The miniaturization and cost reduction of powerful electronics has put the power of the computer age into the hands of automotive engineers. Microprocessors have allowed complex programs involving numerous variables to be used in the control of present day combustion engines, leading to better engine control and performance.
An important facet of combustion engine control is the regulation of air flow into a cylinder by a throttle and accordingly the quantity of fuel delivered into the cylinder. In a combustion engine a throttle, having a movable throttle plate, directly regulates the power produced by the combustion engine at any operating condition by regulating the air flow into the engine. The throttle plate is positioned to increase or decrease air flow into the engine. The engine acts as an air pump with the mass flow rate of air entering the engine varying directly with throttle plate angular position. Presently, there is a need in the art to precisely control throttle plate position in a throttle body to tightly regulate the flow of air and fuel into a cylinder.
In the operation of a standard vehicle combustion engine, a driver will depress the accelerator pedal to generate a portion of a throttle plate position command that varies the throttle plate angle and accordingly varies the air flow into the engine. Other factors besides driver pedal input such as engine temperature, engine speed, exhaust gas oxygen, exhaust gas recirculation valve position, air flow into the engine, and other similar variables will also factor into the a throttle plate position command, but are not limited to such. A control unit coupled to a fuel injector, monitoring the variables cited above, will regulate the fuel that is mixed with the air, such that the injected fuel generally increases in proportion to air flow. If a carburetor is used the air flow through the carburetor will directly regulate the amount of fuel mixed with the air, with respect to the vacuum or suction formed by the air flow through the throttle body. For any given fuel-air mixture, the power produced by the combustion engine is directly proportional to the mass flow rate of air into the engine controlled by the throttle plate position.
SUMMARY OF THE INVENTION
The positioning and stability of the throttle plate directly effects the tuning or stability of the engine. Ideally, when a position command is given to position the throttle plate, the throttle plate will step to that exact position without a large amount of overshoot and undershoot and at a desired angular speed. In practice, control algorithms attempt to approach this ideal condition. Proportional, Integral, and Derivative (PID) algorithms are typically used in the position control of a throttle plate in a throttle body. The output of a typical PID controller or algorithm can be represented by the equation:
 Output=
K
p
e+K
I
∫e
(
t
)
dt+K
D
(
de/dt
)
where
K
p
=the proportional gain
K
I
=the integral gain
K
D
=the derivative gain
and e=the error or difference between the setpoint or position command and the feedback.
In the present invention, a position command is generated using a combination of the operator input on the accelerator pedal and the engine variables cited above. This position command is processed by a PID control program executed on an electronic control unit that outputs a control command to a controller or drive controlling an electric motor. The controller or drive actuates the electric motor in response to the position command, and a position feedback sensor such as a potentiometer provides speed and position feedback for the electronic control unit. The error (the difference between the position command and the position feedback) is processed by the PID control program to generate a control command to the motor controller drive to reposition the motor in response to the error (if one exists). The PID gains in the PID control program and the scale of the error will determine the magnitude of the control command to the motor controller drive and thus the motor response. Higher PID gains (relatively determined by the response of the system) will normally shorten response time (again relative to the performance of the system) but also generate instability in the system. Lower PID gains will lengthen response time but minimize instability in the system.
A single set of PID gains for a throttle control system will normally be determined heuristically for the throttle control system, via the tradeoff between response time and stability in the system. This set of PID gains is traditionally fixed for the entire range of movement, position, and feedback variable values for the control program. This single set of PID gains cannot be optimized for the entire performance range of a throttle plate positioning system. For example, the PID gains that are optimal in a static state to overcome static friction for the motor will not perform as well in a dynamic state, i.e. when the throttle plate is constantly moved between different positions. Inertia generated by the angular speed of the throttle plate will also effect the performance of the system. Large angle changes of the throttle plate vs. small angle changes of the throttle plate have different optimal PID gains. One set of PID gains will not provide optimal performance for all the required moves of a throttle plate.
The present invention has overcome the limitations of the prior art by dynamically recalculating PID gains continuously during operation. A fuzzy supervisory control program will monitor throttle body position feedback and recalculate the PID gains for different error magnitudes, each specific state, speed, and/or position command for the throttle body, but is not limited to such. In this manner, optimal PID gains for every condition the throttle plate is involved in may be used, resulting in improved performance for the throttle system and engine compared to the prior throttle positioning systems.


REFERENCES:
patent: 5454358 (1995-10-01), Hattori et al.
patent: 5498943 (1996-03-01), Kimoto et al.
patent: 5662085 (1997-09-01), Aubourg et al.
patent: 5992383 (1999-11-01), Scholten et al.

Affiliated with

Also associated with

Rating

Electronic throttle control does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Electronic throttle control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electronic throttle control will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2483739