Measuring and testing – Test stand – For engine
Reexamination Certificate
2000-05-02
2001-11-20
McCall, Eric S. (Department: 2855)
Measuring and testing
Test stand
For engine
Reexamination Certificate
active
06318161
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. HEI 11-129793 filed on May 11, 1999 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a diagnostic apparatus for an internal combustion engine.
2. Description of the Related Art
Many internal combustion engines, such as vehicle engines and the like, are equipped with a well known diagnostic apparatus that determine normality/abnormality of the engine and locates an abnormality if any is detected. Such a diagnostic apparatus has a self-diagnostic function, diagnosing an abnormality based on output signals of various sensors that detect operational conditions of the engine. The apparatus constantly diagnoses whether there is a failure, and performs an operation for warning a driver and/or a fail-safe operation, etc.
An example of the aforementioned diagnostic apparatus described in Japanese Patent Application Laid-Open No. HEI 8-75612 detects the occurrence of misfire based on a change in the rotating speed of an output shaft of an internal combustion engine during an explosion stroke of the engine. Based on the frequency of detection of misfire, the apparatus determines whether the engine has an abnormality. Upon determining that the engine has an abnormality, the diagnostic apparatus immediately turns on a warning light to inform a driver of the occurrence of the abnormality.
Although it is important to notify a driver of any detection of abnormality, it is not always the case that the detected abnormality needs urgent treatment; nor is the detected abnormality necessarily permanent. That is, detected abnormalities are often transitory phenomena or phenomena that occur only under specific conditions. Therefore, the abnormality may simply dissolve when the engine is restarted. The incidence of misfire in particular, varies considerably depending on external factors, such as ambient air temperature, pressure conditions, and the like. Thus, even if there is no problem with the internal combustion engine, a misfire abnormality may be indicated depending on the operational condition of the engine, the operation environment, and the like.
Therefore, if a warning is given every time an abnormality is determined, as in the above-described apparatus, the incidence of inappropriate and/or unnecessary warnings will increase so that a driver may be annoyed or may become doubtful. The incidence of a warning can be reduced by elevating a criterion for determining an abnormality. However, an elevated criterion will also reduce the precision of the detection of abnormalities of which the driver needs to be notified.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide an internal combustion engine diagnostic apparatus capable of more appropriately producing necessary warnings regarding abnormalities in an internal combustion engine.
In accordance with the invention, a diagnostic apparatus for an internal combustion engine includes a diagnostic device for diagnosing whether an abnormality of the engine is present, and a condition management device for permitting execution of a warning that indicates the presence of an abnormality on condition that, after a first diagnosis of the presence of an abnormality, a second diagnosis of the presence of an abnormality is made after a restart of the engine.
Therefore, if after the first diagnosis of the presence of an abnormality is made by the diagnostic device, the second diagnosis of the presence of an abnormality is made after a restart of the internal combustion engine, the condition management device permits the execution of the warning, so that the warning is executed. Hence, the diagnostic apparatus reduces the incidence of execution of an unnecessary or inappropriate warning in response to a temporary abnormality that does not have repeatability, for example, an abnormality that disappears merely upon a restart of the internal combustion engine. Thus, the apparatus ensures that the warning regarding an abnormality will be executed in a more appropriate manner.
The above-described diagnostic apparatus may further have a construction wherein the condition management device includes a recovery recognizing device for recognizing whether the internal combustion engine has returned to a normal state, and wherein the condition management device permits the execution of the warning provided that the second diagnosis of the presence of an abnormality is made by the diagnostic device without a return to the normal state being recognized by the recovery recognizing device after the restart of the engine.
With this construction, in the case where after the first diagnosis of the presence of an abnormality is made by the diagnostic device, the return of the engine to the normal state is recognized by the recovery recognizing device, the condition management device does not permit the warning to be executed even if the second diagnosis of the presence of an abnormality is made by the diagnostic device after the engine is restarted. That is, if recognition of the return of the engine to the normal state intervenes between two diagnoses of the presence of abnormalities, the relevancy between the factors for the two abnormalities is considered to be low and, therefore, the warning is not executed. Therefore, it becomes possible to more favorably reduce the incidence of execution of an inappropriate or unnecessary warning
The diagnostic apparatus may further have a construction as follows. That is, the diagnostic device includes a detection device for detecting occurrence of an abnormality of the internal combustion engine, and a determination device for making an abnormality determination regarding the internal combustion engine provided that a result of detection by the detection device meets a predetermined condition. Furthermore, the recovery recognizing device recognizes the return of the engine to the normal state provided that the occurrence of an abnormality is not detected by the detection device during a period between a start of the engine and a stop of the engine.
In this construction, the return of the internal combustion engine to the normal state is recognized on the condition that detection of occurrence of an abnormality, which is referred to as a criterion for the abnormality determination, is not made by the detection device during a period between a start of the engine and a stop of the engine, that is, during one operation of the engine. That is, if the internal combustion engine is operated completely normally during a trip, that is, during an operation of the engine, the relevancy between an abnormality that occurs before the trip and an abnormality that occurs after the trip is considered to be very low and, therefore, the warning regarding such an abnormality is not executed. Therefore, the incidence of an inappropriate or unnecessary warning is further reduced, so that the warning will be executed in a more appropriate situation.
The above-described diagnostic apparatus may further have a construction as follows. That is, the recovery recognizing device includes a first history retaining device (XU) for retaining a history of detection of occurrence of an abnormality by the detection device until the engine stops, and a second history retaining device (XX) for retaining a history indicating that the engine is in the normal state, even after the engine stops, on a condition that the history of detection of occurrence of an abnormality is not retained by the first history retaining device. The recovery recognizing device recognizes the return to the normal state based on a content of the history retained by the second history retaining device.
In this construction, when occurrence of an abnormality is detected by the detection device, the history of the detection of occurrence of an abnormality is retained by the first history retaining device (XU) over a period until the engine stops. A history
Adachi Shin
Amano Hidetoshi
Kenyon & Kenyon
McCall Eric S.
Toyota Jidosha & Kabushiki Kaisha
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