Vehicle engine control device

Details Vehicle engine control device Vehicle engine control device

2002-11-20

2004-06-15

Vo, Hieu T. (Department: 3747)

Data processing: vehicles, navigation, and relative location

Vehicle control, guidance, operation, or indication

With indicator or control of power plant

C701S110000, C701S114000, C123S399000

Reexamination Certificate

active

06751544

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle engine control device, and particularly to a vehicle engine control device in which the safety of additional functions and the performance of escape driving at an emergency are improved in an engine control unit (ECU) for carrying out ignition control of an engine, fuel injection control and the like, especially in a compound type ECU added with, as additional functions, an electronic throttle control function for controlling an opening degree of an intake throttle valve by a driving motor.
2. Description of the Related Art
An engine control unit (hereinafter referred to as an ECU) using a microcomputer is widely used to carry out ignition control and fuel injection control of a vehicle engine. Recently, a compound type ECU added with, as additional functions, an electronic throttle control function for controlling the opening degree of a throttle valve by an electric motor is proposed and is coming into wide use.
This electronic throttle control function is such that the opening degree of an intake throttle valve of an engine is controlled by an electric motor in accordance with the depression degree of an accelerator pedal, and a wireless type one having no accelerator wire is coming into wide use recently.
This type of electronic throttle control device is constructed such that when a power source of the electric motor is switched off at the time of the occurrence of an abnormality, the throttle valve is automatically returned to a position of a predetermined safety throttle valve opening degree by a default mechanism using a return spring.
The safety throttle valve opening degree is set to a valve opening position slightly larger than an idling valve opening position, and in escape driving at the time of the occurrence of an abnormality, an operation of an accelerator pedal becomes ineffective, and one pedal operation is carried out in which vehicle speed is adjusted while the depression degree of a brake pedal is adjusted.
However, if the safety throttle valve opening degree is small, there is a problem that even if the brake is released, a sufficient driving force can not be obtained, and climbing escape driving can not be carried out. On the contrary, if the safety throttle valve opening degree is excessively large, a dangerous state occurs in which even if the brake pedal is sufficiently depressed, it is difficult to stop the vehicle.
Further, it is also necessary to consider such a problem that a default return has not been correctly carried out because of a mechanical abnormality in the throttle valve opening degree control.
As improvement measures to such problems, what is illustrated in FIG.
12
(
a
) or
12
(
b
) is conventionally proposed.
First, the conventional improvement measure illustrated in FIG.
12
(
a
) is an escape driving control in the case where a motor or a throttle valve switching mechanism is abnormal.
An escape driving control circuit shown in FIG.
12
(
a
) includes threshold setting means
1
a
of an upper limit vehicle speed, vehicle speed detection means
1
b
, threshold setting means
2
a
of an idle rotational speed of an engine, rotational speed detection means
2
b
of the engine, upper limit rotation threshold setting means
2
c
of the engine, return detection switches
3
a
and
3
a
of an accelerator pedal, and judgment switches
3
b
and
3
b
of a default return state. Incidentally, reference numeral
4
designates supply fuel control means for controlling a fuel injection amount; and
5
, a fuel injection valve.
In FIG.
12
(
a
), in the state where the judgment switches
3
b
and
3
b
of the default return state are at normal return positions of illustrated positions, and the return detection switches
3
a
and
3
a
of the accelerator pedal are also at illustrated positions of return positions of the accelerator pedal, the fuel injection amount is controlled by the supply fuel control means
4
so that the engine rotational speed comes to have not larger than a threshold set by the idle threshold setting means
2
a
, and the driving force of the engine is put into a minimum state.
In this state, even if the accelerator pedal is depressed to escape from a site, the fuel injection amount is controlled by the supply fuel control means
4
so that the vehicle speed comes to have not larger than a threshold set by the upper limit threshold setting means
1
a
. However, even by the driving function using the depression of the accelerator pedal, when the throttle valve opening degree is small, a sufficient vehicle speed can not be obtained, and this driving function using the depression of the accelerator pedal is absolutely a minimum driving function for the purpose of escaping from the site.
At the time of an excessively opened abnormality in which the return opening degree of the throttle valve becomes a default opening degree or more, or when a throttle position sensor is abnormal and the throttle opening degree is unclear, the detection switches
3
b
and
3
b
of the default return state are changed over from the illustrated positions, and the supply fuel control means
4
is controlled so that the engine rotational speed comes to have not larger than a threshold set by the upper limit rotational speed setting means
2
c.
What is illustrated in FIG.
12
(
a
) is disclosed in JP-A-2000-97087 (Title of the Invention: THROTTLE VALVE CONTROL DEVICE) (prior art 1), and in the state where the detection switches
3
b
and
3
b
of the default return state are at the illustrated positions, the engine rotational speed resulting from the depression of the accelerator pedal is not limited, and the escape driving control illustrated in FIG.
12
(
a
) is suitable for low speed climbing escape driving.
However, in the state where the detection switches
3
b
and
3
b
of the default return state are changed over, the control is carried out such that the engine rotational speed comes to have not larger than the threshold set by the upper limit rotation threshold setting means
2
c
, and in a region of low engine rotational speed, the output torque of the engine is increased in proportion to the rotational speed of the engine, and its proportionality constant is increased or decreased substantially in proportion to the throttle valve opening degree.
Accordingly, in the escape driving control illustrated in FIG.
12
(
a
), even if the upper limit rotational speed of the engine is regulated to the threshold or lower, an actual throttle valve opening degree is uncertain, and it is a problem that the driving torque of the engine is changed by the magnitude of the throttle valve opening degree, and there is a danger that when the throttle valve opening degree is large, braking by the brake pedal becomes difficult.
To this end, if the upper threshold by the upper limit rotation threshold setting means
2
c
is made low, a sufficient driving force can not be obtained, and especially in the case where the throttle valve opening degree is small, there is a problem that the climbing escape running becomes quite impossible.
FIG.
12
(
b
) illustrates a conventional escape driving control in the case where although a driving motor and a throttle valve opening mechanism are normal, an abnormality exists in another portion. The escape driving control illustrated in FIG.
12
(
b
) includes a throttle valve control part shown in the upper stage of the drawing, and a fuel cut control part shown in the lower stage of the drawing.
The throttle control part of the upper stage of FIG.
12
(
b
) is disclosed in JP-A-HEI2-176141 (Title of the Invention: “CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE”) (prior art 2), JP-A-HEI11-141389 (Title of the Invention: “THROTTLE CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE”) (prior art 3), and JP-A-HEI6-229301 (Title of the Invention: “OUTPUT CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE”) (prior art 4) in addition to the prior art 1, and is a typical escape driving control in the case where the driving motor and the throttle valv

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