Internal-combustion engines – Engine speed regulator – Having condition responsive means with engine being part of...
Reexamination Certificate
2000-02-28
2001-03-27
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Engine speed regulator
Having condition responsive means with engine being part of...
C123S357000, C123S361000
Reexamination Certificate
active
06205976
ABSTRACT:
BACKGROUND OF THE INVENTION
In modern controls for motor vehicles and especially for drive units, controllers are often utilized which actuate an actuator in dependence upon the deviation between a pregiven desired value and an actual value of the operating value to be controlled. This actuation is in the sense of bringing the operating variable close to the desired value. Examples of such controllers are controllers for controlling the idle rpm, for controlling the position of a throttle flap, for controlling or limiting the road speed, et cetera. These controllers include controller constants, such as proportional constants, integral constants and/or differential constants whose magnitudes are determined in advance with a view toward the desired stability and dynamic of the control operation. It has been shown that a single set of the abovementioned variables is not sufficient in all areas of application for a satisfactory control over the entire operating range of the controller. This applies especially to the application of actuators having a large nonlinearity.
One example of an actuator having a large nonlinearity is known from U.S. Pat. No. 4,947,815. The throttle flap actuator described therein includes an emergency air position pregiven by springs. That is, the emergency air position is that position which the throttle flap assumes when no power is supplied to the electric motor driving the throttle flap. If this emergency air position is to be passed through, the sign of the drive torque of the actuator motor reverses. This nonlinearity of the actuator element leads to the condition that a compromise for the determination of the parameter set for the controller is achieved only with difficulty. The control performance is therefore not satisfactory in all operating situations.
A PID position controller is disclosed in German patent publication 4,223,253 which is operated with different sets of parameters in order to achieve a different dynamic in various operating modes such as idle control, drive slip control, et cetera. Operation is with fixed parameter sets within individual operating phases so that the above-mentioned problems occur when driving an actuator which is very nonlinear.
U.S. Pat. No. 4,441,471 discloses an example of an idle rpm control wherein the control parameters are pregiven in dependence upon the difference between the desired and actual values.
SUMMARY OF THE INVENTION
It is an object of the invention to improve the control performance of a control loop for an operating variable of a motor vehicle.
The method of the invention is for controlling an operating variable of a motor vehicle which includes an actuator and a controller for forming a drive signal to drive the actuator. The controller has at least one changeable parameter and the actuator has an operating range subdivided into at least first and second operating subranges. The method includes the steps of: providing a desired value of the operating variable and the desired value being change able; detecting an actual value of the operating variable; forming the drive signal in dependence upon the desired value and the actual value; and, changing the at least one parameter of the controller in dependence upon at least one of the following: the particular operating subrarge of the actuator and the magnitude of the change of the desired value.
The control performance of the control loop is improved because different, optimally adapted parameter sets of the control parameters are pregiven depending upon the operating range of the actuator which is part of an actuator assembly which includes, for example, the actuator in the form of an electric motor and a positioning element such as a throttle flap driven by the electric motor. In this way, a nonlinearity, which is present in the actuator, is considered in an advantageous manner via a corresponding selection of the controller parameters whereby, in each operating range, an optimization of the control performance can take place.
It is further especially advantageous that a change of the controller parameters is carried out in dependence upon the magnitude of the change of the desired value of the control loop. In this way, the dynamic of the control loop can be optimally adapted and the complexity of the application is greatly reduced especially with respect to the comparison to the dependency of the parameters from the desired value/actual value deviation. This is so because the parameter switchover only concerns specific jumps in the desired value. The parameters can be adapted optimally to the particular situation. Furthermore, the parameters remain constant during the jump of the desired value. The stability of the control loop is thereby significantly improved.
REFERENCES:
patent: 4441471 (1984-04-01), Kratt et al.
patent: 5048482 (1991-09-01), Kratt et al.
patent: 5144915 (1992-09-01), Grabs
patent: 5233958 (1993-08-01), Knoss et al.
patent: 5293852 (1994-03-01), Lehner et al.
patent: 5370094 (1994-12-01), Sorg et al.
Loehr Diethard
Schmidt Henning
Gimie Mahmoud M
Robert & Bosch GmbH
Walter Ottesen
Yuen Henry C.
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