1. Field of the Invention
This invention relates to an electronic control device for an internal combustion engine.
2. Discussion of the Background
A conventional transient state fuel control for an internal combustion engine detects acceleration of an engine based on a changing ratio of a throttle opening degree or a change of an intake quantity, increases a fuel supply quantity at acceleration initiation by an acceleration fuel increasing means, and afterwards, gradually reduces an acceleration fuel increasing quantity. Furthermore, as a modification of the acceleration fuel increasing quantity control, a device is known wherein the acceleration increasing quantity is kept constant in a predetermined time period instantly after the acceleration, as in, for instance, Japanese Examined Patent Publication No. 44496/1984. However, in those cases, the acceleration increasing quantity is based on the intake quantity, the throttle opening degree, an engine temperature and an engine revolution number, as parameters.
Next, in an ignition timing control for an internal combustion engine, a device is known wherein the acceleration of the engine is detected similarly by the change ratio of the throttle opening degree or the change of the intake air quantity, and a retard angle quantity of the ignition timing is increased upon acceleration. This control is especially effective to a device having a knocking detecting means, as in, for instance, Japanese Examined Patent Publication No. 5786/1985.
In any one of the fuel control or the ignition timing control of the conventional devices, no special consideration is given to property of fuel such that matching is performed so that an air-fuel ratio or the ignition timing in transient state is optimized with respect to a specified fuel.
Furthermore, in the fuel control at starting or at post-starting (just after starting) of the internal combustion engine, a device is known wherein a temperature of the engine is detected, and a fuel quantity at starting is determined in accordance with the temperature, or a fuel increasing value is determined in accordance with the engine temperature at starting, and the fuel increasing value is gradually reduced over time at the post-starting. In the ignition timing control at post-starting of an internal combustion engine, a device is known wherein the temperature of the engine is detected, and the ignition timing is controlled to an advance angle compared with a reference value, in accordance with the engine temperature.
Furthermore, in an idling air quantity control at starting or at post-starting of an internal combustion engine a device is known wherein the temperature of the engine is detected, and an air quantity at starting is determined in accordance with the temperature, or an air quantity increasing value is determined in accordance with the engine temperature at starting, and the increased value is gradually reduced over time at post-starting.
However, even in the fuel control, the ignition timing control and the idling air quantity control of the conventional devices at starting or at post-starting, no special consideration is given to the fuel property such that a matching is performed so that the fuel quantity, the ignition timing and the idling air quantity are optimized at starting and at post-starting, with respect to a specified fuel property.
Since in the conventional electronic control device for an internal combustion engine, no consideration is given the influence of a property difference of fuel on a control in transient time such as at starting or in the acceleration, in the fuel quantity control, the ignition timing control and the idling air quantity control, with respect to a fuel other than the specified fuel, a considerable deterioration of the control of the engine in transient time is caused and a malfunction results wherein the engine cannot be started or the engine is stopped just after starting.
Heavy gasoline is pointed out as a specific example wherein the difference in the fuel property becomes an issue. Heavy gasoline is a gasoline of which distillation temperature is high. As a characteristic feature, the vapor pressure (RVP) thereof is low, and the specific weight and the octane value thereof are high compared with those of a regular gasoline. As a standard, this gasoline is no different than normal gasoline, or with gasoline at a filling station such as a high-octane gasoline or a regular gasoline. The problems encountered in an electronic control device which performs the fuel control, the ignition timing control and the idling air quantity control that are matched to normal gasoline when running an engine filled with the heavy gasoline, are a hesitation at acceleration or an instability of an engine revolution number at starting and at post-starting, which results in the incapability of starting or engine stoppage at post-starting, and also worsening of exhaust gas. The cause of these problems is considered to be that, since the vapor pressure of the heavy gasoline is low, a substantial fuel supply quantity is reduced at the acceleration or at starting and at post-starting due to adhesion of fuel to an intake pipe, thereby increasing the air-fuel ratio and causing a defective combustion.