Internal-combustion engines – Engine speed regulator – Idle speed control
Reexamination Certificate
2001-10-05
2004-06-01
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Engine speed regulator
Idle speed control
C123S339190, C123S339240, C123S352000
Reexamination Certificate
active
06742497
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an engine speed control unit for controlling the engine speed of an internal combustion engine so that it can reach a target value.
2. Background Art
It is important to control the engine speed of an internal combustion engine so that it can reach a target value.
For example, in the case of an automobile, in order to purify exhaust gas to be cleaner or in order to improve drivability, it is necessary to control the engine speed of an internal combustion engine so that it can reach the target value in various conditions.
For example, as the engine speed of an internal combustion engine after the engine has started greatly affects the exhaust gas, that is, as the engine speed of an internal combustion engine in the period from the completion of the initial combustion at starting to the steady state of idling of the engine greatly affects the exhaust gas, it is necessary to control the engine speed after the start of the engine so that the engine speed can reach the target value.
In this connection, one of the reasons why the engine speed fluctuates after the start of an engine is that a failure in burning occurs in a cylinder. Accordingly, in order to prevent the engine speed from fluctuating after the start of an engine, it is necessary to detect the burning state in a cylinder after the engine has started and control the engine speed so that burning can be conducted properly. In order to control the engine speed of an internal combustion engine so that burning can be conducted properly, Japanese Unexamined Patent Publication No. 62-3139 discloses a device by which the degree of throttle opening is controlled to a target value corresponding to the temperature of an internal combustion engine at the start.
However, when a quantity of suction air is changed in the case of a failure in burning, the burning state is further deteriorated. The reason is described as follows. The failure in burning at the start of an engine is caused by a lean air/fuel ratio because fuel is not sufficiently atomized at the start of an engine but adheres onto a wall face of a suction port so that a sufficient quantity of fuel can not be introduced into a combustion chamber. When the degree of throttle opening is controlled so that it can be increased, negative pressure in a suction tube is reduced, and fuel atomization is further deteriorated and the air/fuel ratio becomes much leaner.
The engine speed of an internal combustion engine in the idling steady state greatly affects the exhaust gas. Therefore, it is also necessary to control the engine speed in the idling steady state so that it can reach the target value. In order to accomplish the above object, Japanese Unexamined Patent Publication No. 5-222997 discloses a suitable device. In this device, in the case of a failure of the suction air feedback control system, it is changed over to the ignition timing feedback control system, and when the engine temperature is low, ignition timing feedback control is subjected to restriction.
In the device disclosed in the above unexamined patent publication, in the case of a failure of the suction air feedback control system, it is changed over to the ignition timing feedback control system, however, even if a failure in burning is caused by feedback control conducted by the suction air feedback control system, it is impossible to detect the failure in burning.
Even if a load given to the engine is changed, it is necessary to keep the engine speed at the target value. In order to accomplish the object, Japanese Unexamined Patent Publication No. 59-3135 discloses a device by which feedback control is conducted so that the idling engine speed can be the target value by increasing the rate of control. However, according to the device of the above unexamined patent publication, it is disclosed that the rate of control is increased with respect to the fluctuation of a load given to the engine, however, the device is provided with only a feedback control means conducted by a quantity of suction air. Therefore, it is impossible to conduct feedback control with a parameter other than the quantity of suction air.
Japanese Unexamined Patent Publication No. 62-210240 discloses a device. In this device, in the case where the temperature of engine coolant is low, suction air feedback control is stopped and open control is conducted while the suction air is fixed at a value corresponding to the temperature of engine coolant. This device is characterized in that learning is conducted in the case of obtaining a value corresponding to the temperature of engine coolant. According to the device of the above unexamined patent publication, a quantity of suction air in the case where suction air feedback control is stopped and open control is conducted can be found by learning, and this open control can comply with a change with time or a difference between each products.
However, even in the process of suction air feedback control, of course, control is affected by the change with time or the difference between each products. Therefore, for example, in the case where the engine speed is subjected to feedback control by adding a correction value to a reference value of suction air quantity, a difference between the required value and the reference value is increased by the change with time or the difference between individual bodies. Accordingly, the correction value is increased. As a result, it takes a long period of time for the engine speed to reach the target value.
However, it is impossible for the device of the above unexamined patent publication to solve the above problems although learning is conducted by the device.
In view of the above problems, it is an object of the present invention to provide an engine speed control unit capable of controlling the engine speed so that it can reach the target value.
It is another object of the present invention to provide an engine speed control unit capable of controlling the engine speed at the start of the engine so that it can reach the target value. It is still another object of the present invention to provide an engine speed control unit capable of controlling the engine speed in the idling steady state so that it can reach the target value. It is still another object of the present invention to provide an engine speed control unit capable of controlling the engine speed so that it can reach the target value even if a load give to the engine fluctuates. It is still another object of the present invention to provide an engine speed control unit capable of controlling the engine speed in the idling steady state so that it can reach the target value. It is still another object of the present invention to provide an engine speed control unit capable of removing influences of a change with time and a difference in individual bodies upon feedback control of the engine speed.
SUMMARY OF THE INVENTION
The present invention provides an engine speed control unit of an internal combustion engine for controlling an engine speed so that it can reach a target, comprising: a first engine speed control means for controlling the engine speed by changing a quantity of suction air; a second engine speed control means for controlling the engine speed by changing a control value of a control parameter except for the quantity of suction air; and a burning state judgment means (also referred to as a means for judging a burning state), wherein the engine speed is controlled by the first engine speed control means in the case of a good burning state, and control by the first engine speed control means is stopped and the engine speed is controlled by the second engine speed control means in the case of a bad burning state.
In the engine speed control unit composed as described above, in the case of a good burning state, a quantity of suction air is changed by the first engine speed control means so as to control the engine speed. In the case of a bad burning state, the first engine speed control means stops control
Kanamaru Masanobu
Onaka Hidemi
Watanabe Satoru
Hoang Johnny H.
Toyota Jidosha & Kabushiki Kaisha
Wolfe Willis R.
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