Internal-combustion engines – Engine speed regulator – Idle speed control
Patent
1990-09-24
1992-03-10
Nelli, Raymond A.
Internal-combustion engines
Engine speed regulator
Idle speed control
F02M 300
Patent
active
050942077
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method and an apparatus for adapting the characteristic of an idling adjuster, such as is mounted in the intake section of an internal combustion engine, in order to adjust the charge during idling in such a way that a desired engine speed is maintained.
BACKGROUND OF THE INVENTION
A method and an apparatus to which the invention relates are described in U.S. Pat. No. 4,672,934. A provisional desired air quantity which is to result in a specific desired speed is determined as a function of values of various operating parameters, especially the engine temperature, gear position or switching state of an air-conditioning system. In order to guarantee that this desired speed is actually obtained, the control deviation between the desired speed and actual speed is used to form a value for a regulating air quantity which is added to the value of the provisional desired air quantity in order to obtain the actual desired air quantity. From this desired air quantity, a control value, especially a pulse-duty factor, is calculated for the idling adjuster by means of an air quantity control-value characteristic stored in a memory. When the characteristic is determined correctly, the idling adjuster is controlled by means of the read-out control value exactly in such a way that the actual intake air quantity precisely corresponds to the desired air quantity required. In contrast, if the characteristic is incorrect, for example because of a change in density of the air since the last determination of the characteristic or a change in the leakage-air fraction, an air quantity control deviation between the desired air quantity and actual air quantity is obtained. An adaptation of the mentioned characteristic is carried out by means of this air-quantity control deviation.
Accordingly, the known apparatus for adapting the characteristic curve of an idling adjuster has a speed subtraction means for forming the speed control deviation, an air-quantity subtraction means for forming the air-quantity control deviation, a characteristic memory and an adaptation means. Furthermore, a release means for releasing the adaptation is provided. The adaptation of the slope of the characteristic is released, for example, when a predetermined air-quantity throughput is exceeded. Offset adaptation takes place, for example, whenever the slope adaptation does not occur and a blocking time has elapsed.
When this apparatus and therefore the associated method are used, it has emerged that often less quiet running is obtained after a starting operation then without this apparatus and without this method.
On the one hand, it is the object of the invention to provide a method for adapting the characteristic curve of an idling adjuster by means of which smooth engine running can be achieved quickly, even after a starting phase. On the other hand, it is the object of the invention to provide an apparatus for carrying out such a method.
SUMMARY OF THE INVENTION
In the method according to the invention, the adaptation is carried out only when the speed control deviation has the same sign as the air-quantity control deviation. Accordingly, in the apparatus according to the invention, the release means is designed in such a way that it compares with one another the signs of parameters having the same signs as the speed control deviation and the air-quantity control deviation, and releases the adaptation only when the signs of the compared parameters correspond to one another.
The invention makes use of the following fact regarding operations in the starting phase of an engine and in the subsequent phase. In the starting phase, the air quantity and fuel quantity are controlled in such a way that the engine comes up to speed as quickly as possible. When a predetermined speed of, for example, 500 rpm is reached, there is a change-over from open-loop control to closed-loop idle control. After this change-over, the speed as a rule overshoots the predetermined idling speed, for example 700 rpm, and then
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patent: 4274381 (1981-06-01), Abo
patent: 4580535 (1986-04-01), Danno et al.
patent: 4672934 (1987-06-01), Peter et al.
patent: 4909213 (1990-03-01), Mezger et al.
patent: 4993383 (1991-02-01), Wokan et al.
Janetzke Helmut
Krampe Wolfgang
Wild Ernst
Nelli Raymond A.
Ottesen Walter
Robert & Bosch GmbH
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