Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-01-31
2001-11-27
Solis, Erick (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C073S117020, C073S035020
Reexamination Certificate
active
06321721
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based on Japanese Patent Application No. 11-20988 filed on Jan. 29, 1999, No. 11-287476 filed on Oct. 8, 1999, and No. 11-356807 filed on Dec. 16,1999, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel property detecting apparatus for detecting a property of fuel supplied to an internal combustion engine.
2. Description of Related Art
A usual gasoline engine mounted on vehicle are mostly arranged that an intake pipe is equipped with a fuel injection valve. Fuel (gasoline) is injected into an intake port. In this intake port injection system, a part of fuel injected from the fuel injection valve is directly introduced into cylinders. The rest of fuel adheres on an inner surface of the intake port and a surface of an intake valve, and it gradually evaporates and is introduced into the cylinders. Accordingly, the amount of fuel introduced into the cylinders varies according to an amount of evaporating fuel which adheres on the inner surface of the intake port or the like (wet). The amount of evaporating fuel (rate of an evaporation) varies according to the property of fuel, but the property of fuel is not stabilized even among the same kind of fuel. The property is different between makers, and is changed according to the season and sales area even in the same makers fuels. Accordingly, it is necessary to detect the fuel property in order to provide an accurate air-fuel ratio control (fuel injection control) by considering the amount of evaporating fuel.
It is proposed that the fuel property is detected on the basis of each of parameters such as an ability to start, a variation of the rotation and a rising of the rotation as described in JP-A-9-203342.
However, the ability to start, the variation of the rotation and the rising of the rotation are varied according to various factors except for the fuel property. Therefore, it is impossible to detect the fuel property accurately, even if the fuel property is detected by using these parameters, since it is influenced by the various factors except for the fuel property. For instance, in a manual-mission car, there are possibilities of an erroneous detection, because the variation of the rotation and the rising of the rotation varies a lot according to a shift-operation by driver.
As a result, a driveability, a fuel consumption and an emission might become worse, since an accuracy of a correction by the fuel property is lowered.
SUMMARY OF THE INVENTION
The present invention was accomplished in consideration of the above-mentioned circumstances, and, the object is to provide a fuel property detecting apparatus for an internal combustion engine that the apparatus is able to detect the fuel property accurately.
In order to achieve the above-mentioned object, the present invention apply to the fuel property detecting apparatus for an internal combustion engine. The injection amount of fuel which is injected from a fuel injection valve or a parameter having a correlation with the injection amount (hereafter generally referred as an injection amount parameter) is calculated by an injection amount parameter calculating means. The combustion amount of fuel which is burnt in the cylinder or a parameter having a correlation with the combustion amount (hereinafter generally referred as a combustion amount parameter) is calculated by means for calculating a combustion amount parameter. Then, the fuel property is detected based on a relationship between the injection amount parameter and the combustion amount parameter.
For instance, a volatility of fuel (ability of evaporation) decreases as the fuel property becomes heavier. The amount of fuel adhered on the inner wall of the intake port or the like (wet amount) is increased and a ratio of the combustion amount to the injection amount of fuel is decreased. Therefore, the relationship between the injection amount and the combustion amount of fuel varies according to the fuel property. Accordingly, it is possible to detect the fuel property accurately, when the fuel property is detected based on the relationship between the injection amount parameter and the combustion amount parameter.
Here, in a case that the combustion amount of fuel is used as the combustion amount parameter, an intake air amount of the internal combustion engine can be detected by an intake air amount detecting means. Air-fuel ratio in exhaust gas can be detected by an air-fuel ratio detecting means. The combustion amount can be calculated by using the detected values. That is, the combustion amount of fuel can be calculated, when the intake air amount and air-fuel ratio in exhaust gas are used, because air-fuel ratio in exhaust gas is defined by the intake air amount and the combustion amount of fuel. Further, it is not necessary to dispose new sensor for detecting the combustion amount parameter, because a usually disposed sensors for air-fuel ratio control can be used for detecting the intake air amount and air-fuel ratio in exhaust gas. Therefore, the costs can be cut down.
A fuel supply excess rate, which is a reciprocal of an air excess rate of a mixture supplied for the internal combustion engine, can be calculated as the injection amount parameter. A combustion fuel excess rate, which is the reciprocal of an air excess rate of exhaust gas, can be calculated as the combustion amount parameter. For instance, a ratio of the combustion fuel excess rate to the fuel supply excess rate is decreased by increasing the wet amount as the fuel property becomes heavier. Therefore, the relationship between the fuel supply excess rate and the combustion fuel excess rate fuel varies according to the fuel property. Accordingly, it is possible to detect the fuel property accurately, when the fuel property is detected based on the relationship between the fuel supply excess rate and the combustion fuel excess rate fuel. In a case that the invention is applied to the system which calculates the combustion fuel excess rate based on an output signal of an air-fuel ratio sensor and controls air-fuel ratio. The invention can simplify a calculating process for the fuel property detection, because the process for calculating the combustion amount parameter is extremely simplified.
Further, the fuel property is detected by comparing an accumulated value of the combustion amount parameter and an accumulated value of the injection amount parameter during a predetermined time. As a result, it is possible to improve a detecting accuracy of the fuel property, because it is possible to reduce an influence of noise and a variation of an operating condition.
Further, the fuel property is detected by comparing an accumulated value of a difference between the injection amount parameter and the combustion amount parameter and the accumulated value of the injection amount parameter during a predetermined time. That is, the difference between the injection amount and the combustion amount is used as a parameter for evaluating the wet amount adhering on the inner wall of the intake port or the like. The ratio of the wet amount to the injection amount increases as the fuel property becomes heavier. Accordingly, it is possible to detect the fuel property accurately, by comparing the accumulated value of the difference between the injection amount parameter and the combustion amount parameter and the accumulated value of the injection parameter during the predetermined time.
Further, it is considered that the wet amount varies in accordance with the operating condition of the internal combustion engine. At least one of the injection amount parameter and the combustion amount parameter or a relationship therebetween or a fuel property detecting criterion are corrected according to the operating condition of the internal combustion engine. As a result, it is possible to carry out the stable detection of the fuel property which is not dependent on the operating condition of the internal combustion engin
Kawai Katsuhiko
Okumura Hiroshi
Denso Corporation
Nixon & Vanderhye P.C.
Solis Erick
LandOfFree
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