Internal-combustion engines – Combustion chamber means having fuel injection only – Combustible mixture stratification means
Reexamination Certificate
2000-04-27
2001-07-10
Solis, Erick (Department: 3747)
Internal-combustion engines
Combustion chamber means having fuel injection only
Combustible mixture stratification means
C123S14250R
Reexamination Certificate
active
06257198
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an engine to be mounted in a vehicle equipped with a heater that uses engine coolant as a heating source, and, more particularly, to a combustion control apparatus and combustion control method for an engine that carries out stratified-charge combustion (stratified combustion).
An engine has been proposed that carries out stratified combustion, in which fuel is non-uniformly injected into the combustion chamber of the engine near the ignition plug, and homogeneous-charge combustion (homogeneous combustion), in which fuel is uniformly distributed in the combustion chamber (see Japanese Unexamined Patent Publication (KOKAI) No. Hei 8-189405, for example).
Generally, during the stratified combustion, the temperature of the combustion gas that contacts the inner wall of the combustion chamber is relatively low, thus reducing the amount of heat transferred to the engine coolant through the inner wall. This makes the cooling loss lower than that of homogeneous combustion. Since the air-fuel mixture is leaner during stratified combustion, the throttle valve is opened more widely, accordingly. This makes the pumping loss lower than that of homogeneous combustion.
Because of the reductions in cooling loss and pumping loss, stratified combustion reduces fuel consumption as much as possible while providing about the same engine power as that provided by the homogeneous combustion.
While an engine that carries out stratified combustion consumes less fuel, it raises the following significant problem when used in a vehicle equipped with a hot water heater for heating the interior of the vehicle.
Since the rate of heat transferred to the coolant is lower during stratified combustion, the temperature of the coolant also becomes lower than that of homogeneous combustion. Because the hot water heater uses this coolant as the heat source, the heat output may be inadequate.
In particular, if stratified combustion is performed in a low-engine-load mode, such as when idling, which relatively reduces the amount of fuel injection as described in the aforementioned Japanese publication, the amount of combustion heat generated in the combustion chamber is smaller. This further reduces the heat output of the heater.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a combustion control apparatus and combustion control method for an engine that improves the heating performance of a heater that uses the coolant of the engine as its heat source.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, an apparatus for controlling an engine used in a vehicle is provided. The vehicle has a heater that uses engine coolant as a heating source. The engine operates in a stratified-charge-combustion mode, in which a mixture of air and fuel is non-uniformly injected into a combustion chamber. The apparatus includes determination means and a controller. The determination means determines whether the heating performance of the heater is insufficient. When the heating performance of the heater is determined to be insufficient, the controller controls the engine such that the engine heat efficiency falls below that of the stratified-charge-combustion mode.
The present invention may also be embodied in a method for controlling an engine used in a vehicle. The vehicle has a heater that uses engine coolant as a heating source. The engine operates in a stratified-charge-combustion mode, in which a mixture of air and fuel is non-uniformly injected into a combustion chamber. The method includes: determining whether the heating performance of the heater is insufficient; and controlling the engine such that the engine heat efficiency falls below that of the stratified-charge-combustion mode when the heating performance of the heater is determined to be insufficient.
REFERENCES:
patent: 5931380 (1999-08-01), Aoki et al.
patent: 6044642 (2000-04-01), Nishimura et al.
patent: 6155230 (2000-12-01), Iwano et al.
patent: 8189405A (1996-07-01), None
patent: 9303169A (1997-11-01), None
Kenyon & Kenyon
Solis Erick
Toyota Jidosha & Kabushiki Kaisha
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