Internal-combustion engines – Charge forming device – Including exhaust gas condition responsive means
Reexamination Certificate
2002-01-18
2004-09-21
Kwon, John (Department: 3747)
Internal-combustion engines
Charge forming device
Including exhaust gas condition responsive means
C123S549000, C073S114220, C073S118040
Reexamination Certificate
active
06792929
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to internal combustion engines for vehicles or the like, and more particularly, to a method for detecting a failure of injection fuel heaters provided in a fuel injection system of an internal combustion engine.
2. Description of the Prior Art
In order to preserve the atmospheric environment, modern internal combustion engines for vehicles or the like are equipped with injection fuel heaters in the fuel injection system thereof, whereby in the cold start of the engine the fuel heaters are operated, so that the fuel injected into the intake port or the combustion chamber is better atomized for a better combustion, so that thereby the emission of CO and HC by the exhaust gas of the engine is decreased as much as possible.
The fuel heaters are provided each at a housing portion of a fuel injection valve or at a fuel supply passage for supplying fuel to the fuel injection valve at a position adjacent its entrance, the fuel injection valves being provided each for each cylinder of the engine. The fuel heaters are each adapted to heat the fuel to be injected by a heat generated therein according to an electric resistance or an electromagnetic induction.
Those heaters are operated under such severe conditions of the engine that they are constantly subjected to violent vibrations and high temperatures, and are therefore not free from failure. It is desirable that, when one has failed, the failure is detected without delay. Further, since the heaters are separately provided for respective cylinders, it is desirable that it is known which of them has failed.
The internal combustion engines of automobiles or the like are multi-cylinder internal combustion engines having four or more cylinders. Therefore, when the fuel heaters are provided separately at respective fuel injection valves or in the vicinity thereof for the plurality of cylinders, the same number of fuel heaters are provided as the number of cylinders. Even when those plurality of fuel heaters are manufactured according to the same design and the same production process and are mounted to one engine at the same time, it is generally not foreseen which of those plurality of heaters will fail under a synergistic influence of an unavoidable fluctuation of the finished condition of the products and a small difference of each working environment. When one of them has failed, it is important that, in addition to the fact of the failure, the failed heater is specified.
The fuel heaters herein concerned are electrically operated devices, in which the failure is generally a severance in its current conducting portion. Therefore, such a failure would be readily detected with an identification of the individual heater when a galvanometer or a similar current detecting means is provided in the current supply passage for each heater. However, it increases correspondingly substantially the cost of the internal combustion engine to provide such a current detecting means for each of a plurality of fuel heaters corresponding to the number of cylinders.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to detect a failure of the fuel heaters with no addition of the conventional current detection means which causes an engine cost increase, by, instead, utilizing the microcomputer of a vehicle operation control device generally mounted in the modern automobiles, with such input information available from those sensors generally already provided in those vehicles, such as an air/fuel ratio sensor or a crankshaft rotation speed sensor.
According to the present invention, the above-mentioned object is accomplished by a method for detecting a failure of heaters provided in a fuel supply system of an internal combustion engine for heating a fuel injected, characterized by detecting the failure based upon a change which occurs at least in a parameter concerned with operating conditions of the engine due to the injected fuel not having been heated to a predetermined degree of heating.
In the above-mentioned method for detecting a failure of the heaters, the change in the parameter may be an increase of air/fuel ratio of an exhaust gas of the engine as compared with a value thereof to be expected when the injected fuel has been heated to the predetermined degree of heating.
Or, in the above-mentioned method for detecting a failure of the heaters, the change in the parameter may be a change in a performance of at least one of rotational speed, rotational acceleration and changes thereof of the engine corresponding to one of cylinders thereof.
Further, in the above-mentioned method for detecting a failure of the heaters, the change in the parameter may be a substantial non difference between values of the parameter according to operations of the engine with the heater being put on and the heater not being put on, respectively.
Further, in the above-mentioned method for detecting a failure of the heaters, the change in the parameter may be a substantial difference in values thereof between cylinders of the engine.
Further, the heaters for respective cylinders of the engine may be operated with a time shift therebetween in order to detect the difference in the parameter between an operation of the engine with the heaters being put on in a predetermined manner and an operation of the engine with the heaters not being put on.
The time shift in the operations of the heaters for the respective cylinders may be such that the heaters for the respective cylinders are put on with a time shift therebetween, or the heaters for the respective cylinders are put off with a time shift therebetween.
Or alternatively, two cylinders which are most distant from one another in the phases of operation of the engine may be made a pair of cylinders, and the heaters for such pairs of cylinders may be operated with a time shift therebetween in order to detect a difference in the parameter between an operation of the engine with the heaters being operated in a predetermined manner and an operation of the engine with the heaters not being operated.
In this case, also, the time shifted operations for the respective cylinders may be such that the heaters are put on with a time shift between respective such pairs of cylinders, or the heaters are put off with a time shift between respective such pairs of cylinders.
It is in the operation of several tens of seconds from the starting of the internal combustion engine in a cold state that the operation of the fuel heaters are required and they exhibit their effects. Just after the cold start of the engine, since the temperature of the wall of the combustion chamber of the engine is low, the fuel ejected from the fuel injection valve is apt to stick to the wall surfaces of the intake port and the combustion chamber as a liquid.
When such a sticking of the fuel to the wall surfaces of the intake port and the combustion chamber occurs, the fuel-air mixture becomes correspondingly lean, so that the engine is liable to fail in starting or the rotation of the engine becomes irregular. Such a fuel sticking to those wall surfaces can be temporarily met by temporarily increasing the amount of fuel injection. However, the fuel stuck on the wall surfaces is irregularly shifted toward the exhaust port with a part thereof combusted in the meantime while other remaining in liquid, thereby in any event causing a rough rotation of the engine and a deterioration of the exhaust gas purification.
In view of the above, the fuel heater is operated so as to heat the fuel ejected from the fuel injection valve, so that the injected fuel is better atomized, suppressing the fuel sticking to the wall surfaces of the inlet port and the combustion chamber in a liquid form, so that the engine rotates smoothly with a supply of fuel and air in a stoichiometric ratio from the beginning of the engine starting, thereby also making the exhaust gas to be stoichiometric.
Nevertheless, if the fuel heater for any one of the cylinders fails, so that the fuel injected in
Hiraku Keizo
Kanai Hiroshi
Kidokoro Toru
Sato Kazuki
Suzuki Hideki
Kwon John
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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