Internal-combustion engines – Charge forming device – Including means responsive to instantaneous change in engine...
Patent
1996-02-26
1997-12-09
Dolinar, Andrew M.
Internal-combustion engines
Charge forming device
Including means responsive to instantaneous change in engine...
73116, F02D 4114
Patent
active
056949014
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method for determining, in a vehicle with an internal combustion engine mounted thereon, whether the vehicle is running on a rough road or not, and especially to a rough road determination method suitable for use with an internal combustion engine or the like which performs burning at a lean limit.
BACKGROUND ART
A variety of controls have conventionally been performed on individual components of an automotive vehicle, such as the engine, transmission, power steering, suspensions and brakes. As a parameter for changing over the control modes of each of these controls, it is meaningful to determine what kind of road surface condition a road on which the automotive vehicle is running has.
Further, upon detection of a misfire or the like of an engine from the state of a revolution variance or the like of the engine, there is the problem that no accurate determination can be made with respect to the misfire if the vehicle is running on a rough road, because information on the road surface is included in the state of the revolution variance. In determining a misfire on the basis of the state of a revolution variance, it is therefore important to improve the accuracy in determining whether the vehicle is running on a rough road or not.
Lean-burn internal combustion engines (i.e., so-called lean-burn engines) have been provided in recent years, which perform a lean-burn operation at an air/fuel ratio on a side leaner than a stoichiometric air/fuel ratio under predetermined operation conditions.
In such lean-burn engines, the air/fuel ratio is set as high as possible (in other words, an air-fuel mixture is set as lean as possible) during a lean-burn operation so that the emission of NOx can be decreased. The value of the air/fuel ratio is generally set close to a limit (lean limit) within which the air-fuel mixture can undergo stable combustion.
To perform a lean-burn operation, it is common practice to control the state of combustion by a control system. A method of this control that has been contemplated is to estimate engine torque from an angular acceleration of the crankshaft, to perform this estimation moment by moment by using varying momentary values, and then to perform stable and precise control at predetermined intervals while taking into consideration the probabilistic and statistical nature of the engine torque.
Further, the state of combustion in a lean-burn operation is controlled in relation to the air/fuel ratio of the cylinder that is undergoing the greatest combustion variance. When a vehicle equipped with such control means runs on a rough road, influence of the rough road appears as a revolution variance of the engine, thereby possibly making it difficult to determine whether the revolution variance has been caused by a deterioration in combustion or by the rough road.
Described specifically, when a large revolution variance takes place due to running on a rough road, the control system may be excessively corrected to a rich side, resulting in the potential problem that the emission of NOx may be increased.
As has been described above, it is considered necessary for various purposes to determine whether a vehicle is running on a rough road or not. There is hence an outstanding demand for a determination method of low price and high accuracy. An object of the present invention is to provide such a determination method.
DISCLOSURE OF THE INVENTION
Therefore, a method according to the present invention for the determination of a rough road in a vehicle with a multi-cylinder internal combustion engine mounted thereon comprises: detecting any revolution variance with respect to each cylinder in said internal combustion engine; and based on detection of revolution variance states in plural cylinders, respectively, each of the revolution variance states indicating a deterioration in combustion, determining or estimating that the vehicle with the internal combustion engine mounted thereon is running on a rough road.
In the method of the present invent
REFERENCES:
patent: 5016593 (1991-05-01), Takaoka
patent: 5311773 (1994-05-01), Bradshaw et al.
Okada Kojiro
Omori Shogo
Togai Kazuhide
Dolinar Andrew M.
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
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