JPH0571407A - Misfire detector for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a misfire detector for an internal combustion engine which makes use of vibration when the engine has explosion without using a pressure sensor. CONSTITUTION:A rotary encoder 13 outputs pulse signals to set detection ranges A-F corresponding to an explosion timing for each cylinder in an internal combustion engine 10. An acceleration sensor 11 provided for every cylinder detects explosive vibration at the timing in the corresponding detection range. A control means 15 compares vibration computed from engine load with the explosive vibration to judge that the cylinder has misfire or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a misfire detecting device for an internal combustion engine which can detect misfire of each cylinder by utilizing explosive vibration of the internal combustion engine.

[0002]

2. Description of the Related Art In a multi-cylinder internal combustion engine, one or more cylinders are misfired during operation due to a stop of fuel supply due to a failure of an injection nozzle, a fuel pump or the like or a failure of an ignition device. It may end up. In order to detect such misfire, conventionally, a pressure sensor is provided for each cylinder and the internal pressure of each cylinder is directly measured.

[0003]

According to the conventional misfire detecting device, since an expensive pressure sensor must be provided for each cylinder, there is a problem that the entire device becomes complicated and expensive. .. Further, in an internal combustion engine having a high explosion pressure, it has been difficult to use it for a long period of time because of the durability of the pressure sensor.

The present invention eliminates the use of pressure sensors
An object of the present invention is to provide a misfire detection device that can detect misfire of each cylinder by utilizing vibration when an engine explodes.

[0005]

A misfire detecting device for an internal combustion engine according to the present invention comprises a vibration detecting means for detecting explosive vibration successively generated in each cylinder of the internal combustion engine, and a crank angle of the internal combustion engine. Crank angle detecting means for setting the detection range of the explosion vibration corresponding to the explosion timing of each cylinder, and control means for judging the misfire of the cylinder by comparing the vibration detected in each detection range with a reference vibration. It is equipped with.

[0006]

The internal combustion engine operates, and the crank angle detecting means sets the detection range of the explosion vibration corresponding to the explosion timing of each cylinder. The vibration detection means detects the explosion vibration of each cylinder for each detection range. The control means compares the vibration detected by the vibration detection means with the reference vibration to determine whether or not the cylinder corresponding to each detection range is misfiring.

[0007]

FIG. 1 is a block diagram showing the configuration of this embodiment. The internal combustion engine 10 of this embodiment is a six-cylinder cylinder having cylinders 1 to 6, and the crankcase of the internal combustion engine 10 has an acceleration sensor 11 as a vibration detecting means near each cylinder.
Are provided respectively.

Further, the internal combustion engine 10 is provided with rotary encoders 12 and 13 as crank angle detecting means. As shown in FIG. 3, the rotary encoder 12
Outputs a trigger signal in time with the explosion of the cylinder 1. As shown in FIG. 3, the rotary encoder 1
3 outputs a pulse signal so as to set detection ranges A to F of the explosion vibration corresponding to the explosion timings of the cylinders 1 to 6.

Further, as shown in FIG. 1, the internal combustion engine 10 is provided with a load sensor 14.

As shown in FIG. 1, the acceleration sensor 11, the rotary encoders 12 and 13, and the load sensor 14 described above are used.
Is connected to the control means 15. As shown in FIG. 3, when the internal combustion engine 10 is operating, the acceleration sensor 11 corresponding to each of the detection ranges A to F set by the rotary encoder 13 detects the explosion vibration by each cylinder, and the detection result is Output to the control means 15. The control means 15 calculates the reference vibration at the time of explosion corresponding to the load based on the signal from the load sensor 14. Then, the control means 15 is configured to compare the reference vibration with the explosion vibration to determine whether or not the cylinder is misfiring. The CRT 16 is adapted to display the status of misfire detection by this device at any time.

Next, the operation of the above configuration will be described. In FIG. 2, a trigger signal is input from the rotary encoder 12 to the control means 15 in S1. In S2,
When the signal from the rotary encoder 13 is input, the acceleration sensor 11 of the cylinder corresponding to the detection range starts measuring the vibration of the crankcase, and when the signal from the rotary encoder 13 is input, the vibration measurement ends. That is, the explosion vibration of the specific cylinder corresponding to the detection range set by the signal of the rotary encoder 13 is detected.

As shown in S3, the control means 15 calculates the area of the measured vibration waveform. Next, as shown in S4, the control means 15 further measures the load of the internal combustion engine 10 by the signal from the load sensor 14 and calculates the area of the waveform of the explosion vibration by the specific cylinder from the measurement result. Then, the control means 15 compares the area actually measured in S5 with the area calculated from the load.

When the measured area is smaller than the area calculated from the load, the cylinder is judged to have misfired as shown in S6, and the misfire count is incremented by 1 and this misfire count is predetermined. When the set number of times is exceeded, a misfire alarm is displayed on the CRT 16.

When the measured area is larger than the area calculated from the load, the misfire count is cleared and it is judged that the combustion is normal as shown in S7, and the number of cylinders is counted. That is, as shown in S8, when the count of the number of cylinders that are normally burning is 6 or less, S2
The following procedure is repeated to measure each cylinder in sequence, but when the normal combustion is judged to be the seventh time, the count of the number of cylinders is cleared and the No. The measurement of each cylinder is restarted, starting from one cylinder.

In this embodiment, since the area of the vibration waveform is used to compare the detected vibration and the vibration calculated from the load, the adverse effect of noise is less likely to occur as compared with the comparison using the peak value of each vibration. This has the effect of making it easier to obtain more accurate results.

Further, in this embodiment, since the acceleration sensor 11 is provided corresponding to each cylinder, the explosion vibration of each cylinder corresponding to each detection range A to F is obtained in a clear pattern as shown in FIG. Was given. However, the number of acceleration sensors 11 may be smaller than the number of cylinders. In that case, the vibration pattern of the cylinder obtained by the specific acceleration sensor when the specific cylinder normally burns is accurately grasped in advance so that it can be reliably distinguished from the vibration pattern of the cylinder at the time of misfire. You can leave it.

[0017]

According to the misfire detecting device for an internal combustion engine according to the present invention, the explosion detecting vibration of each cylinder is detected by the vibration detecting means while the timing is determined by the crank angle detecting means. There is an effect that a misfire can be reliably detected.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a flow chart showing an operation of the embodiment.

FIG. 3 is a waveform chart of various signals input to the control means in the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 11 Acceleration sensor as vibration detection means 12 Control means 13 Rotary encoder as crank angle detection means

Claims (1)

[Claims] 1. A vibration detecting means for detecting explosive vibrations sequentially generated in each cylinder of an internal combustion engine, and a detection range of the explosive vibration corresponding to an explosion timing of each cylinder by detecting a crank angle of the internal combustion engine. A misfire detecting device for an internal combustion engine, comprising: a crank angle detecting means for controlling a cylinder; and a control means for comparing a vibration detected in each of the detection ranges with a reference vibration to determine a misfire of the cylinder.