Electronic throttle control apparatus

Details Electronic throttle control apparatus Electronic throttle control apparatus

2002-10-29

2004-07-27

Solis, Erick (Department: 3747)

Internal-combustion engines

Engine speed regulator

Open loop condition responsive

C123S361000

Reexamination Certificate

active

06766785

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic throttle control apparatus adapted to drivingly open and close a throttle valve disposed in an intake passage by means of an actuator in a gasoline engine or a diesel engine.
2. Description of Related Art
There has conventionally been known an electronic throttle control apparatus which is used in a gasoline engine or a diesel engine for a motor vehicle and others. This electronic throttle control apparatus is provided with an electronic throttle including a throttle valve of a linkless type which is disposed in an intake passage in the engine and is drivingly opened and closed by an actuator such as a motor and a controller for controlling the actuator. This controller determines a target opening degree of the electronic throttle (namely, the throttle valve) based on an operated amount of an accelerator pedal operated by a driver. The controller makes feedback control on the actuator by PID control and the like based on a deviation of opening degree between the determined target opening degree and an actual opening degree of the throttle valve detected by a throttle sensor, thereby controlling the electronic throttle so that the actual opening degree approaches the target opening degree.
In the above electronic throttle apparatus, a response and a stable convergence in operations of the electronic throttle often become problems. One of techniques taking those points into consideration is disclosed in Japanese patent unexamined publication No. 10-176579, which is entitled “Throttle valve control apparatus”.
In this control apparatus, a controller determines a driving signal (=a control amount) of a throttle valve based on the product obtained by multiplying an opening degree deviation between a requested opening degree (=a target opening) and an actual opening degree of the throttle valve by a control coefficient (=a control gain). The controller has previously stored data on control coefficients (proportional gains and integrating gains) determined according to an opening degree deviation. The data is set such that the smaller the opening degree deviation is, the larger control coefficient is determined. The controller provisionally determines a control coefficient with reference to the above data if the throttle valve opening degree is in a transitional state at the time when the controller receives a signal representing an opening degree deviation. The controller then compares the provisionally determined value of control coefficient with a control coefficient value used in a previous cycle to select a smaller one. The controller calculates a value of a driving signal by multiplying the opening degree deviation by the selected control coefficient. The controller controls the motor based on the calculated value of the driving signal to drivingly open and close the throttle valve.
The above control is explained in detail with reference to a flowchart in FIG.
11
. The controller first calculates an opening degree deviation ER between a target opening degree RTA and an actual opening degree VTA in a step
200
and calculates an absolute value (an absolute opening degree deviation) AER of the opening degree deviation ER in a step
201
.
In a step
202
, the controller determines whether or not the absolute opening degree deviation AER is smaller than a predetermined value A1. If an affirmative decision is made in the step
202
, the controller determines that the throttle opening degree is in a steady state and, in a step
220
, sets a gain KPb for a steady operation as a final proportional gain KP. In a step
221
, the controller sets a gain KIb for the steady operation as a final integrating gain KI and advances the flow to a step
209
.
If a negative decision is made in the step
202
, on the contrary, the controller determines that the throttle opening degree is in a transitional state and, in the step
203
, calculates a proportional gain tKP from the absolute opening degree deviation AER by referring to a proportional gain map (Map
1
). In a step
204
, the controller calculates an integrating gain tKI from the absolute opening degree deviation AER by referring to an integrating gain map (Map
2
). These proportional gain tKP of the proportional gain map and the integrating gain tKI of the integrating gain map have both been set to become smaller as the absolute opening degree deviation AER becomes larger.
In a step
205
, the controller then determines whether or not the proportional gain tKP calculated at this time is larger than the final proportional gain KP used at a previous time. If an affirmative decision is obtained in the step
205
, the controller advances the flow directly to a step
207
. If a negative decision is obtained, on the contrary, the controller updates the final proportional gain KP by the proportional gain tKP calculated at this time and then advances the flow to the step
207
. More specifically, since this-time absolute opening degree deviation AER is larger than the previous absolute opening degree deviation AER, the proportional gain tKP which is smaller than the previous final proportional gain KP is selected as this-time final proportional gain KP. This is referred to as “minimum select”.
In a step
207
following the step
205
or
206
, the controller determines whether or not the integrating gain tKI calculated at this time is larger than the final integrating gain KI used at a previous time. If an affirmative decision is made, the controller advances the flow directly to a step
209
. If a negative decision is made in a step
208
, the controller updates the final integrating gain KI by the integrating gain tKI calculated at this time and then advances the flow to the step
209
. More specifically, since this-time absolute opening degree deviation AER is larger than the previous absolute opening degree deviation AER, the integrating gain tKI which is smaller than the previous final integrating gain KI is selected as this-time final integrating gain KI. In other words, the “minimum select” is conducted.
In the step
209
following the step
207
,
208
, or
221
, the controller calculates a proportional term VP by multiplying this-time final proportional gain KP by the opening degree deviation ER obtained at this time. In a step
210
, the controller calculates an integral term VI by adding the product of this-time final integrating gain KI and this-time opening degree deviation ER to an addition result accumulated up to the previous time. In a step
211
, the controller furthermore calculates a PI control amount (controlled variable) VPI by adding the proportional term VP calculated at this time and the integral term VI. In a step
212
, the controller converts the PI control amount VPI calculated at this time to a duty ratio DUTY by using a predetermined function expression.
In a step
213
, the controller then controls the motor based on the converted duty ratio DUTY to drivingly open and close the throttle valve.
The feature of the above routine is in determination of the final proportional gain KP and the final integrating gain KI by way of the “minimum selects”. This can be shown by a block diagram in FIG.
12
. In a block B
1
, the controller first calculates the opening degree deviation between the target opening degree and the actual opening degree. In a block B
2
, the controller calculates the control gain according to the opening degree deviation. In a block B
3
, the controller executes the minimum select to select a smaller one of the calculated control gains. In a block B
4
, then, the controller determines the control gain obtained by the minimum select as the final control gain.
More specifically, the conventional throttle valve control apparatus has stored the proportional gain tKP and the integrating gain tKI corresponding to the absolute opening degree deviation AER in the form of map. However, even if the absolute opening degree deviation AER is reduced by the motion of the throttle valve, the fi

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