Interrelated power delivery controls – including engine control – Transmission control – Control by sensed ambient condition – pattern indicia,...
Reexamination Certificate
1999-01-27
2001-06-19
Wright, Dirk (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
Control by sensed ambient condition, pattern indicia,...
Reexamination Certificate
active
06248040
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an engine system and engine control method, in which a catalyst can be warmed up fast after the start of an engine when the engine and the cataylst is still in a cold state.
Harmful components in exhaust gas of an internal combustion engine cause the problem of air pollution. Therefore, a catalyst converter is generally used in the internal combustion engine, which converts the harmful materials to harmless materials.
The catalyst converter does not work sufficiently when the temperature of the catalyst does not reach the predetermined temperature. Therefore, the harmful components are not processed and emitted as they are, when the catalyst is in a cold state (for example, just after the start of an engine). In order to solve such the problem, various methods of warming up fast the catalyst have been proposed in the prior art.
For example, Japanese Patent Application Laid-Open No. 61-205376 and Japanese Patent Application Laid-Open No. 6-213125 disclose a method of activating fast a catalyst due to increased temperature of exhaust gas, in which the amount of correction of retard of an ignition timing is increased according to the temperature of the engine in a cold state, that is, the increasement state of the temperature of a coolant, or the elapsed time after the start of the engine.
It is, however, difficult to warm up the catalyst with giving a comfortable feeling of acceleration in the prior art, because the ignition timing is retarded due to indirect informations such as the temperature of the coolant of the engine, etc.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an engine system in which a stable operation can be maintained from the standing start under warming-up to the running under acceleration, the temperature of catalyst can be rapidly increased up, and the harmful exhaust gas can be clarified fast.
The first aspect of the present invention relates to an engine system. In the engine system, an ignition timing is changed in accordance with the operation parameters of the engine. The engine system includes an exhaust gas clarifying equipment with a catalyst to clarify the specified components in the exhaust gas, catalyst temperature detecting means for estimating or detecting the temperature of the catalyst, torque fluctuation detecting means for detecting the state of the fluctuation of an output torque of the engine, and ignition timing calculating means for calculating the final ignition timing on the basis of the detected results of the torque fluctuation detecting means and the catalyst temperature detecting means.
The ignition timing calculating means advance the final ignition timing when the fluctuation of output torque of the engine is larger than the predetermined value, as compared with it is smaller than one.
Preferably, the ignition timing calculating means include correction ignition timing calculating means for calculating the correction amount of retard on the basis of the detected results of said catalyst temperature detecting means and said torque fluctuation detecting means, and final ignition timing calculating means for calculating the final ignition timing, by using the correction amount of retard and a normal ignition timing determined in accordance with the operation parameter of the engine.
Advantageously, the correction ignition timing calculating means lessen the correction amount of retard angle when the fluctuation of output torque of the engine is larger than the predetermined value.
Advantageously, the torque fluctuation detecting means detect the timing at which the output torque of the engine reaches its peak, and detect the fluctuation of output torque on the basis of the magnitude of variations of the timing.
Preferably, the torque fluctuation detecting means include crank angle detecting means and calculating means for calculating the time-varing rate of the crank angle.
Preferably, the torque fluctuation detecting means include cylinder internal pressure detecting means for detecting the internal pressure of a combustion chamber of the engine.
Advantageously, the ignition timing calculating means determine the ignition timing obtained on the basis of the operation parameters of the engine as the final ignition timing, when the temperature of catalyst is outside the predetermined range.
Preferably, the ignition timing calculating means include correction ignition timing calculating means for calculating the correction amount of retard on the basis of the detected results of the catalyst temperature detecting means and the torque fluctuation detecting means, and final ignition timing calculating means for obtaining the final ignition timing, by using the correction amount of retard angle and a normal ignition timing determined in accordance with the operation parameter of the engine.
Preferably, the correction ignition timing calculating means set the correction amount of retard to zero when the temperature of the catalyst is outside the predetermined range.
Preferably, the predetermined range of temperature is between the temperature at which the catalyst starts clarification of CO and the temperature at which it starts clarification of HC.
In a preferred embodiment, the engine system includes further exhaust gas state detecting means for detecting the components of exhaust gas or air/fuel ratio, reaction start determining means for determining whether or not the temperature of the catalyst reaches the temperature at which it becomes possible to clarify the specified materials, on the basis of the temperature of the catalyst obtained by the catalyst temperature detecting means, target secondary air amount setting means for determining air amount induced to an exhaust pipe, on the basis of the detected result of the exhaust gas state detecting means, and secondary air inducing means for inducing the air amount determined by the target secondary air amount setting means into the exhaust pipe in the upper stream of the exhaust gas clarifying equipment, when the reaction start determining means determine that the temperature of the catalyst reaches the temperature at which it becomes possible to clarify the specified materials.
Preferably, the engine system includes further crank angle detecting means for detecting a crank angle of the engine, wherein the secondary air inducing means start to induce an air to the exhaust pipe at the timing when an exhaust valve of the engine is closed, on the basis of the result detected by the crank angle detecting means.
Preferably, the engine system further includes air/fuel ratio control means for controlling independently the air/fuel ratio of air mixture in each cylinder, wherein said secondary air inducing means induce an air to the exhaust pipe at the timing when an exhaust valve in the cylinder which the amount of fuel injection is increased is closed, in order to lessen the target air/fuel ratio provided to the engine by the air/fuel ratio control means.
In a further embodiment, the engine system further include crank angle detecting means for detecting an engine speed and a crank angle, target air/fuel ratio setting means for setting the air/fuel ratio of air mixture supplied to the engine, fuel injection amount calculating means for obtaining the amount of fuel injection required to realize the air/fuel ratio set by the target air fuel ratio setting means, reaction start determining means for determining whether or not the catalyst reaches the temperature at which it becomes possible to clarify the specified material on the basis of the temperature of the catalyst obtained by the catalyst temperature detecting means, and fuel injection system for supplying to the engine the amount of the fuel injection obtained by the fuel injection amount calculating means, when the reaction start determining means determine that the temperature of the catalyst reaches the temperature at which it becomes possible to clarify the specified materials.
Preferably, the engine system further include air mixture forming
Kashiwaya Mineo
Minowa Toshimichi
Ochi Tatsuya
Ohyama Yoshishige
Yoshida Yoshiyuki
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Hitachi , Ltd.
Wright Dirk
LandOfFree
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