Internal-combustion engines – Starting device – Condition responsive control of starting device
Reexamination Certificate
2002-08-15
2004-08-10
Gimie, Mahmoud (Department: 3747)
Internal-combustion engines
Starting device
Condition responsive control of starting device
Reexamination Certificate
active
06772723
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automatic stop and start control system for an internal combustion engine mounted on a vehicle, which controls automatically stopping and restarting the engine, when the vehicle is stopped (an idle stop control for stopping unnecessary idling of the engine).
2. Description of the Related Art
A hybrid vehicle employs an internal combustion engine and an electric motor in combination. A conventional technique for idle stop control is known. When restarting the engine with the conventional technique, the motor is first operated to perform cranking and the engine is started at the time the engine rotational speed becomes a starting rotational speed (Japanese Patent Laid-open No. 2000-204997).
In the technique described in the above publication, the starting rotational speed is set to a value which decreases with an increase in the required drive force. Thus, when the required drive force increases, the engine is started earlier. Accordingly, when the driver of the vehicle depresses an accelerator pedal immediately after starting of the engine, the engine is restarted earlier.
But in some circumstances, it is preferable to perform engine restarting as quickly as possible irrespective of the magnitude of the required drive force to reduce the load on the motor in the hybrid vehicle. In the case of performing the idle stop control in a normal vehicle driven by only an internal combustion engine, the engine restarting must be performed as quickly as possible. For example, when the removal of a depression force applied to a brake pedal is detected, it may be determined that the driver intends to start the vehicle.
FIGS. 12A
to
12
E are time charts illustrating engine restart control in the prior art, which is directed to a four-cylinder internal combustion engine.
FIG. 12A
shows the strokes in the four cylinders (#1, #2, #3, and #4 cylinders).
FIG. 12B
shows an output from a brake switch for detecting the condition of a brake (the low level in
FIG. 12B
indicates the release of the brake).
FIG. 12C
shows TDC pulses generated immediately before the piston in each cylinder reaches a top dead center.
FIGS. 12D and 12E
respectively show drive control signals for fuel injection valves and ignition signals for four cylinders.
When the brake is released and a starter motor is operated to start cranking the engine, simultaneous injections of fuel into the four cylinders is carried out after generation of the first TDC pulse P
11
. At this time, the fuel is first introduced into the #4 cylinder on the intake stroke, and is next ignited by a spark generated by a spark plug for the #4 cylinder in the explosion (combustion) stroke after the compression stroke, thus generating the first explosion. When contemplating the #4 cylinder in which the first explosion is generated, this cylinder is on the exhaust stroke during stoppage of the engine, and shifts to the intake stroke after starting the cranking, via the compression stroke, to reach the explosion stroke. That is, about one and half revolutions of a crankshaft are required until the first explosion is generated after starting the cranking, and the first explosion is generated after the generation of three TDC pulses P
11
, P
12
, and P
13
.
FIG. 13
is a time chart showing changes in engine rotational speed and generation of TDC pulses, when actually starting the engine using the control method shown in
FIGS. 12A
to
12
E. As understood from
FIG. 13
, the first explosion is generated after generating three TDC pulses after starting the cranking.
It is preferable, however, to restart the engine after the idle stop as quickly as possible. Thus, further improvement is desired.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide an automatic stop and start control system for an internal combustion engine, which can restart the engine quicker than the prior art.
To attain the above object, the present invention provides an automatic stop and start control system for a multiple-cylinder internal combustion engine mounted on a vehicle. The control system controls automatically stopping and restarting the engine according to operating conditions of the vehicle and the engine. The control system includes fuel supply stop control means and fuel supply start control means. The fuel supply stop control means provides fuel to at least one of the cylinders of the engine when an engine stop condition for stopping the engine is satisfied. And then stops the fuel supply to all of the cylinders of the engine. The fuel supply start control means immediately supplies fuel to at least one of the cylinders at the time an engine restart condition for restarting the engine is satisfied.
With this configuration, the fuel supply is provided to at least one of the cylinders of the engine when the engine stop condition is satisfied, and subsequently the fuel supply to all of the cylinders of the engine is stopped. Thereafter, at the time the engine restart condition is satisfied, fuel is immediately supplied to at least one of the cylinders of the engine. By providing the fuel supply to at least one cylinder upon stoppage of the engine, the combustion (first explosion) is carried out by the first ignition pulse upon restart of the engine, and by supplying fuel at the beginning of restart of the engine, the combustion by the second ignition pulse is subsequently carried out. Accordingly, the first explosion can be generated earlier and the engine restarted quicker than in the prior art.
Preferably, when the engine stop condition is satisfied, the fuel supply stop control means first stops the fuel supply to a first predetermined number of cylinders and then provides fuel to at least one cylinder.
In the above configuration, “the first predetermined number” is set so that the at least one cylinder to which the fuel is supplied stops in the compression stroke when the engine is stopped. Specifically, the first predetermined number is set to “2” for a four-cylinder engine. This number is also set to “2” for six-cylinder or eight-cylinder engines. That is, the first predetermined number is set to a fixed value regardless of the number of cylinders.
With this configuration, the fuel supply to the first predetermined number of cylinders is first stopped when the engine stop condition is satisfied. Then the fuel supply is provided to the at least one cylinder. Accordingly, the engine can be reliably stopped, and the emission of unburnt fuel can be prevented.
Preferably, the control system further includes ignition control means for first carrying out ignitions of a second predetermined number of cylinders when the engine stop condition is satisfied, and then suspending the subsequent ignition.
In the above configuration, “the second predetermined number” is set to the number of such cylinders that the fuel is supplied before the engine stop condition is satisfied and the ignition timing comes after the engine stop condition is satisfied. Specifically, the second predetermined number is set to “2” for a four-cylinder engine, “3” for a six-cylinder engine, and “4” for an eight-cylinder engine.
With this configuration, the ignition to the second predetermined number of cylinders is carried out when the engine stop condition is satisfied, and the subsequent ignition is suspended. Accordingly, the fuel supplied before the engine stop condition is satisfied, can be reliably burned, and unnecessary ignitions after the engine stop condition is satisfied, can be prevented.
Preferably, the vehicle has a motor capable of rotationally driving an output shaft of the engine and performing a regenerative operation for converting rotational energy of the output shaft into electrical energy. The control system further includes regeneration control means for performing the regenerative operation of the motor when the engine stop condition is satisfied.
With this configuration, the regenerative operation of the motor is performed
Aoki Shigeru
Kuroda Shigetaka
Arent & Fox PLLC
Castro Arnold
Gimie Mahmoud
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