Internal-combustion engines – Engine speed regulator – Engine speed reduction by fuel cutoff
Reexamination Certificate
1999-12-02
2001-08-14
Solis, Erick (Department: 3747)
Internal-combustion engines
Engine speed regulator
Engine speed reduction by fuel cutoff
C123S396000, C123S399000
Reexamination Certificate
active
06273061
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a throttle control apparatus for a vehicle engine, and particularly to a control apparatus provided with a redundant sensor structure for controlling the throttle.
BACKGROUND OF THE INVENTION
There is known an engine of a vehicle provided with a throttle control apparatus having an electrically operated throttle valve. For example, a throttle control apparatus
202
is shown in
FIG. 7
wherein an electrically operated throttle valve
204
is installed in an intake path
206
and the throttle valve
204
is operated by a motor
208
for throttle movement. The throttle driving motor
208
communicates with a throttle control unit
210
-
1
of a control means
210
.
To carry out a failsafe operation, a sensor system with a twofold or redundant detecting structure is provided. The throttle control apparatus
202
includes first and second throttle position sensors
212
-
1
and
212
-
2
, and first and second accelerator position sensors
216
-
1
and
216
-
2
communicating with an accelerator pedal
214
. The motor
208
for throttle movement includes first and second motor drive coils
218
-
1
and
218
-
2
.
The first throttle position sensor
212
-
1
communicates with the throttle control unit
210
-
1
through a power source supply line
220
-
1
, a ground line
222
-
1
and an electrical signal output line
224
-
1
. The second throttle position sensor
212
-
2
communicates with the throttle control unit
210
-
1
by an electrical signal output line
224
-
2
.
The first accelerator position sensor
216
-
1
communicates with an engine control unit
210
-
2
by a power source supply line
226
-
1
, a ground line
228
-
1
and an electrical signal output line
230
-
1
. The second accelerator position sensor
216
-
2
communicates with the engine control unit
210
-
2
by a power source supply line
226
-
2
, a ground line
228
-
2
and an electrical signal output line
230
-
2
.
The first motor drive coil
218
-
1
communicates with the throttle control unit
210
-
1
by a power source supply line
232
-
1
and a ground line
234
-
1
. The second motor drive coil
218
-
2
communicates with the throttle control unit
210
-
1
by a power source supply line
232
-
2
and a ground line
234
-
2
.
Thereby, when a sensor communication route of any one of the first and second throttle position sensors
212
-
1
and
212
-
2
, the first and second accelerator position sensors
216
-
1
and
216
-
2
or the drive coils
218
-
1
and
218
-
2
fails, the driver is informed of the failure by lighting a failure display lamp
236
. There is also installed a throttle wire
238
for escape vehicle running during a failure by which the throttle valve
204
is operated such that the vehicle can be driven to a service station. In this case, when one sensor communication route fails, then, for example, there are cases in which supply of power source to the motor
208
for throttle driving is stopped and the vehicle is run at a default opening degree mechanically provided to the throttle valve
204
. That is, the throttle is fixed with a throttle opening degree &thgr;=15°, or the throttle valve
204
is mechanically operated via the throttle wire
238
for escape running.
Further, such a failsafe sensor structure is disclosed in, for example, Japanese Patent Laid-Open No. 99058/1993 or Japanese Patent Laid-Open No. 209809/1997. According to the structure described in Japanese Patent Laid-Open No. 99058/1993, there are provided two detecting means for detecting the operating state of a vehicle and operating control of the vehicle is carried out in accordance with an output state of the detecting means. When both of the detecting means are determined to be normal, an object of the control is further safely controlled. According to the structure described in Japanese Patent Laid-Open No. 209809/1997, there are installed multifold detecting means, and in determining detection signals, a determination is carried out in accordance with whether the changing speed of respective detection values fall in reference ranges to thereby promote certainty and conformity of failsafe.
In the throttle control apparatus having two control circuit routes, when one of the control circuits fails, throttle control is carried out by using the other control circuit. However, when one of the two control circuit routes fails (or may be described otherwise as “determined to fail”), there is a high possibility of its being accompanied with other failure in respect to an engine controller or a throttle controller of the control means and when normal throttle opening degree control is carried out, this a concern of causing unnecessary throttle operation in running the vehicle and an improvement has been desired.
However, according to a conventional throttle control apparatus, in the case of a failure of a onefold (i.e., non-redundant) sensor, the throttle control apparatus carries out a corresponding failsafe control when the sensor system fails. Main functions of the failsafe control are notifying an abnormality to the driver by turning on a malfunction indicating lamp (MIL) when the sensor system fails and carrying out a simplified control for escape running such that a vehicle can be driven to a service station which can repair the vehicle.
The function of carrying out the simplified control for escape running can be explained as a function that places a power source of the throttle driving motor in an OFF state when the sensor system fails and allows the vehicle to run with the throttle valve being at a default opening degree mechanically provided to it (for example, opening degree is fixed to 15 degree). Thus, it is intended to run the vehicle by setting the throttle valve to the default opening degree, the vehicle is run regardless of the intention of the driver and, accordingly, there is an inconvenience in which needed depression force exerted on a brake pedal is increased, and a strange feeling is caused in running the vehicle.
Further, in an apparatus which does not carry out the simplified control for escape running, there is an apparatus provided with an auxiliary wire for escape running. According to this construction, the throttle opening degree of the throttle valve is mechanically opened and closed by the wire to thereby enable running when the sensor system is failed. Moreover, when the vehicle is run by mechanically operating the throttle valve with the throttle wire for escape running, there are inconveniences in that the throttle wire and peripheral parts are needed, the number of parts is increased, the construction is complicated and the apparatus becomes increasingly expensive.
SUMMARY OF THE INVENTION
Hence, according to an aspect of the invention, in order to remove the above-described inconveniences and drawbacks of conventional throttle controllers, there is provided a throttle control apparatus for an engine which executes a fuel cut operation at a predetermined engine rotational number to prevent overrevolution the high rotational number region, a throttle valve which is electrically operated to control an operating state of the engine, and a twofold (redundant) detecting means, wherein the control means executes the start of the fuel cut of the engine at a lower rotational number than the predetermined rotational number when one of the twofold detecting means is in a failed state.
According to the invention, when one of the twofold detecting means fails, in consideration of the possibility that the other detecting means may be failed in accordance therewith, it becomes possible that by controlling the engine in a specific operational state, there is no need of increasing the depression force of a brake pedal, strange feeling during running a vehicle can be avoided with parts such as a throttle wire and so on are not needed, the number of parts is reduced, the construction is simplified and the apparatus can be made inexpensively.
According to another aspect of the invention, there is provided a throttle control apparatus having a
Flynn ,Thiel, Boutell & Tanis, P.C.
Solis Erick
Suzuki Motor Corporation
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