Apparatus for detecting misfire in internal combustion engines for vehicles

• US 5,263,453 A
• Filed: 10/31/1991
• Issued: 11/23/1993
• Est. Priority Date: 11/01/1990
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Wakahara, Keiji, Shimizu, Kouichi, Hotta, Minoru
• Primary Examiner(s): DOMBROSKE, GEORGE M
• Application Number:
  US07/785,321
• Time in Patent Office: 754 Days
• Field of Search: 123/479, 123/481, 123/630, 123/436, 73/117.3, 73/116
• US Class Current: 123/436
• CPC Class Codes: G01M 15/11 by detecting misfire

Abstract

An apparatus for detecting a misfire in an internal combustion engine for a vehicle includes a rotational speed change quantity computing unit which detects a rotational speed of the engine and computes a change quantity of the rotational speed of the engine, a misfire determination value correction coefficient setting unit which detects a load on the engine and sets a correction coefficient of a misfire determination value based on a result of detection of the engine load, a misfire determination value setting unit for setting a misfire determination value based on the set misfire determination value correction coefficient, and a misfire determining unit for determining whether a misfire has occurred in the engine by comparing the change quantity of the rotational speed of the engine from the rotational speed change quantity computing unit with the misfire determination value from the misfire determination value setting unit. The misfire detecting apparatus further includes a misfire detection result invalidating unit for invalidating a result of misfire determination by the misfire determining unit.

Claims

1. An apparatus for detecting a misfire in an internal combustion engine for a vehicle, comprising:

misfire detecting means for detecting occurrence of a misfire in an internal combustion engine for a vehicle;

misfire processing means for executing a misfire processing when said misfire detecting means detects occurrence of a misfire;

vehicle condition detecting means for detecting a condition of a vehicle;

vehicle condition determining means for determining whether the vehicle condition has an influence on the detection of a misfire by said misfire detecting means in accordance with a detection output of said vehicle condition detecting means;

means for invalidating a result of detection of said misfire detecting means when said vehicle condition determining means determines that the vehicle condition has an influence on the detection of a misfire by said detecting means; and

wherein said vehicle has an electronic meter and an electronic meter control device which controls an operation of the electronic meter and which is provided with said vehicle condition determining means.

2. An apparatus for detecting a misfire in an internal combustion engine for a vehicle as defined in claim 1, further comprising:

load change value setting means for setting a load change value which is determined depending on a time elapsed from a load condition change of the internal combustion engine; and

means for prohibiting determination of occurrence of a misfire when it is determined that a change of the internal combustion engine load condition is large, in accordance with a result of setting of said load change value setting means.

3. An apparatus for detecting a misfire in an internal combustion engine for a vehicle, comprising:

misfire detecting means for detecting occurrence of a misfire in an internal combustion engine for a vehicle;

misfire processing means for executing a misfire processing when said misfire detecting means detects occurrence of a misfire;

vehicle condition detecting means for detecting a condition of a vehicle;

vehicle condition determining means for determining whether the vehicle condition has an influence on the detection of a misfire by said misfire detecting means in accordance with a detection output of said vehicle condition detecting means;

means for invalidating a result of detection of said misfire detecting means when said vehicle condition determining means determines that the vehicle condition has an influence on the detection of a misfire by said detecting means;

wherein said vehicle condition detecting means includes at least one of means for detecting that a residual fuel quantity of the vehicle is not more than a given quantity;

means for detecting that a vehicle speed is not lower than a given value; and

means for detecting that the vehicle is in a braked condition; and

wherein said vehicle has an electronic meter and an electronic meter control device which controls an operation of the electronic meter and which is provided with said vehicle condition determining means.

4. An apparatus for detecting a misfire in an internal combustion engine for a vehicle as defined in claim 3, further comprising:

loading change value setting means for setting a load change value which is determined depending on a time elapsed from a load condition change of the internal combustion engine; and

means for prohibiting determination of occurrence of a misfire when it is determined that a change of the internal combustion engine load condition is large, in accordance with a result of setting of said load change value setting means.

5. An apparatus for detecting a misfire in an internal combustion engine for a vehicle, comprising:

rotational speed change quantity computing means which detects a rotational speed of the internal combustion engine and computes a change quantity of the rotational speed of the internal combustion engine;

misfire determination value producing mean for producing a misfire determination value which is determined by an operating condition of the internal combustion engine;

load change value setting means for setting a load change value which is determined depending on a time elapsed from a load condition change of the internal combustion engine;

means for determining whether a misfire has occurred by comparing a result of computation of said rotational speed change quantity computing means with the misfire determination value;

means for prohibiting determination of occurrence of a misfire when it is determined that a change of the internal combustion engine load condition is large, in accordance with a result of setting of said load change value setting means; and

wherein said load change value setting means sets a load change value in accordance with a combination of load change values determined by load conditions of a plurality of internal combustion engines.

6. An apparatus for detecting a misfire in an internal combustion engine for a vehicle, comprising:

means for detecting a rotational speed of the engine;

means for computing a change quantity of the rotational speed of the engine based on an output signal from said rotational speed detecting means;

means for detecting a load on the engine;

means for setting a correction coefficient to correct a misfire determination value based on a result of detection of said load detecting means;

means for setting the misfire determination value based on a result set by said misfire determination value correction coefficient setting means;

misfire determining means for determining whether a misfire has occurred in the engine by comparing the change quantity of the rotational speed of the engine supplied from said rotational speed change quantity computing means with the misfire determination value supplied from said misfire determination value setting means;

means for invalidating a result of misfire determination by said misfire determining means when it has been determined that at least one of the vehicle and the engine is in such an operating condition that misdetermination of a misfire is apt to be made; and

means for stopping or continuing fuel supply to the engine in accordance with a result of misfire determination by said misfire determining means, a result of invalidation processing by said misfire determination result invalidating means and whether the engine operating condition corresponds to an engine operating condition stored in a storage means in which a misfire has occurred.