Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
2002-04-23
2004-09-28
Knight, Anthony (Department: 2121)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S029000, C701S051000, C701S054000, C123S332000, C123S337000, C123S397000, C123S399000, C123S1980DA, C477S020000, C700S054000, C700S071000, C700S079000
Reexamination Certificate
active
06799110
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic control system of an intake amount for an engine that is used in an engine control unit (ECU) for carrying out an ignition control, a fuel injection control and the like of an automobile engine, particularly in a composite type ECU in which an electronic throttle control function for controlling a throttle valve opening by means of an electric motor is added, and in which safety of the additional function and evacuation operation performances under abnormal state are improved.
2. Background Art
An electronic throttle control system for controlling a throttle valve opening for an intake of an engine in accordance with a depression degree of an accelerator pedal using an electric motor has been widely put into practical use. Recently a wireless type that does not have any accelerator wire has been coming into wide use.
This type of electronic throttle control system is arranged such that when a power supply for the electric motor is interrupted upon occurrence of any abnormality, the throttle valve is automatically returned to a predetermined safe throttle valve opening position by a default mechanism employing a return spring.
The above-described safe throttle valve opening is set to be at a valve opening position a little larger than an idle operating valve opening position. And evacuation operation is carried out in the form of one pedal operation conducting a creep travelling while regulating the depression degree of the brake pedal.
However, in the case that the above-described safe throttle valve opening is small, a problem exists in that even if the brake is released, any sufficient drive force cannot be obtained, and therefore any hill climbing evacuation operation cannot be carried out. On the contrary, in the case that the safe throttle valve opening is excessively large, there arises a dangerous state of having difficulty in stopping the vehicle in spite of sufficiently depressing the brake pedal.
Further, it is necessary to take into consideration such a problem that a default return is not carried out properly due to a mechanical trouble in the throttle valve opening control.
To cope with such problems as described above, a prior art employed a technical improvement as shown in
FIGS. 17
a
to
17
d.
FIG. 17
a
shows an evacuation operation method in the case that a motor or a throttle valve open/close mechanism is abnormal, and the throttle valve is returned to the valve opening position below a predetermined default position.
In the drawing, reference numeral
1
a
designates threshold setting means for the upper limit (supremum) vehicle speed, and numeral
1
b
designates vehicle speed detecting means. Numeral
2
a
designates threshold setting means for an idle engine speed, and numeral
2
b
designates engine speed detecting means of the engine. Numerals
3
a
,
3
b
designate return detecting switches for the accelerator pedal. Numeral
4
designates supply fuel control means for controlling a fuel injection amount, and numeral
5
designates a fuel injection valve. When the accelerator pedal is returned, the fuel amount is controlled by the supply fuel control means
4
so that the engine speed may be not more than the threshold value set by the threshold value setting means
2
a
. Thus the drive force of the engine comes to be in a minimum state. Furthermore when the accelerator pedal is depressed, the fuel amount is controlled by the supply fuel control means
4
so that the vehicle speed may be not more than the threshold value set by the threshold value setting means
1
a.
However, in this prior art, the throttle valve opening is so small that a sufficient vehicle speed cannot be obtained. To the utmost, it is a driving function at a lowermost limit intending to get out of the trouble spot.
The operation control system shown in
FIG. 17
a
is disclosed in the Japanese Patent Publication (unexamined) No. 97087/2000, titled “Throttle Valve Control System” (Reference 1). This operation control system is suitably applied when the throttle valve opening at the time of stopping the motor is not more than the default opening. During the accelerator pedal being depressed, the engine speed is not limited and therefore this operation method is suitable for a low-speed hill climbing evacuation operation.
As a further characteristic of this prior control system a two-pedal operation system is employed based on the generally accepted conception that acceleration is to be conducted by means of the accelerator pedal, and the deceleration is to be conducted by means of the brake pedal. However, a most serious problem exists in this type of control system that the accelerator pedal cannot perform a function of proportionally increasing or decreasing the vehicle speed or engine speed.
The operation control system shown
FIG. 17
b
is applied to the above-described Example 1, in which under the abnormal state that the throttle valve opening at the time of stopping the motor is not less than the default opening. In this operation system, the supply fuel control means
4
is controlled in such a manner that the engine speed may be not more than the threshold value set by the upper limit engine speed setting means
2
c.
On the other hand, in the region of a low engine speed, output torque of the engine increases in proportion to the engine speed, and proportional constant thereof increases or decreases substantially in proportion to the throttle valve opening.
Accordingly, a problem exists in this type of control system that even if the upper limit engine speed is regulated so as to be not more than the threshold value, the actual throttle valve opening is indefinite, and that engine drive torque is varied depending upon the valve opening. Further there is a possibility that braking by means of the brake pedal becomes difficult in the case of large valve opening.
Therefore, supposing that the upper limit threshold engine speed might be lowered, any sufficient drive force cannot be obtained. In particular, a problem exists in that the hill climbing evacuation travelling cannot be carried out at all in the case of small valve opening.
The operation system shown in
FIG. 17
c
is disclosed, besides in the foregoing Example 1, in the Japanese Patent Publication (unexamined) No. 176141/1990 titled “Control System for Internal Combustion Engine” (Example 2), the Japanese Patent Publication (unexamined) No. 141389/1999 titled “Throttle Control System of Internal Combustion Engine” (Example 3), the Japanese Patent Publication (unexamined) No. 229301/1994 titled “Output Control System of Internal Combustion Engine” (Example 4), etc. This operation is a typical evacuation operation method in the case that the motor or the throttle valve open/close mechanism is in the normal state.
In the drawing, numeral
6
a
designates an accelerator position sensor (referred to as APS) that detects the degree of the depression of the accelerator pedal. Numeral
7
designates target throttle valve opening setting means in response to the output detected by the APS. Numeral
6
b
designates a throttle position sensor (referred to as TPS) that detects the throttle valve opening in cooperation with an open/close controlling motor
9
for the throttle valve. Numeral
8
designates PID control means for controlling the above-described motor
9
so that the target throttle valve opening set by the setting means
7
may coincide with an actual valve opening by means of the throttle position sensor
6
b
. The arrangement described above is the same as that under the normal operation.
However, in the case of occurring any other abnormality except in the motor or the drive mechanism, the target throttle valve opening set by the setting means
7
is a restrained value as compared with that under the normal operation.
In the case of the above-described Example 2, there is proposed abnormality detecting means for detecting an abnormality in output voltage level, abnormality of sudden change, abnormality in rela
Hashimoto Kohji
Nakamoto Katsuya
Barnes Crystal J.
Knight Anthony
Mitsubishi Denki & Kabushiki Kaisha
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