JPH04101048A - Infrared temperature detection type combustion abnormality judging method - Google Patents

Abstract

PURPOSE:To enable momentary judgment on which cylinder combustion abnormality exists even without touching an engine by judging as combustion abnormality when a sensor of an infrared thermometer is brought close to an exhaust port of each cylinder and a detected temperature difference between before and after ignition of the engine is less than a set lower limit. CONSTITUTION:Infrared thermometers 6 are provided in the number of cylinders, and a sensor 7 of each of the thermometers 6 is set close to the position about 3mm from a mating face 9 with a cylinder head exhaust port 3 of an exhaust manifold 5. Next, temperature at the same position is continuously detected for one second for each cylinder and the average value is stored. After that, an engine is ignited and started, and the temperature for one second after the time about ten seconds have passed since engine starting is continuously detected, and the average value is stored. And at a judging device 23, a temperature difference between the temperature average value before the engine ignition and the temperature average value after the engine starting is calculated for each of the cylinders, and when the temperature difference calculated for each of the cylinders is smaller than a lower limit, it is judged that combustion abnormality exists at that cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for determining combustion abnormality during a test run of an automobile engine.

Conventional technology When test running a car engine, such as a gasoline engine, methods for detecting combustion abnormalities include measuring sound and vibration, measuring unevenness in engine output, and even looking at the color of exhaust gas. Possible methods include measuring the gas acid content in exhaust gas.

Problems to be Solved by the Invention However, these methods require the measurement device to be brought into contact with the engine, take time to measure, do not provide sufficient accuracy in measurement, and have problems with only one cylinder being connected to the engine. , it may not be possible to determine which cylinder has a combustion abnormality.

The present invention was developed to solve the above problems, and is a combustion engine that can instantly and with sufficient accuracy determine which cylinder has a combustion abnormality without directly contacting the engine. The purpose is to provide an abnormality determination method.

Means for Solving the Problems The present invention has been made to achieve the above-mentioned objects.The present invention has been made to achieve the above-mentioned object.The present invention is made by bringing an infrared thermometer sensor close to the exhaust port of each cylinder of an automobile engine, and measuring the detected temperature before and after ignition of the engine. If the difference is less than or equal to a set lower limit value, it is determined that combustion is abnormal.

Operation During engine commissioning, the infrared thermometer sensor only needs to be located close to the exhaust port and does not need to be in contact with the engine. Additionally, temperature detection is instantaneous and accurate. By setting an infrared thermometer in each cylinder, it is easy to determine which cylinder has a combustion abnormality.

EXAMPLE Hereinafter, an example of the present invention will be explained with reference to FIGS. 1 and 2. FIG. 1 is a longitudinal sectional view of the engine showing the portions where temperature is detected, and FIG. 2 is a flowchart showing a determination procedure for determining combustion abnormality based on temperature detection.

FIG. 1 is a partial cross-sectional view showing only one cylinder of a gasoline engine for an automobile having a plurality of cylinders. An exhaust manifold 5 is connected to an exhaust port 3 formed in a cylinder head 2 provided at the top of a cylinder block I in each cylinder. According to the present invention, the sensor 7 of the infrared thermometer 6 is set close to, for example, a position of about 3M1R from the mating surface 9 of the exhaust manifold 5 and the cylinder head exhaust boat 3. This setting is performed using a jig that can clamp the sensor 7 and bring it closer accurately. Note that 11 is an intake boat formed in the cylinder head 2, and 13 is an intake port 11.
15 is an injector installed in the intake manifold 13 and injects a portion of the fuel; 21 is an intake valve 17 and an exhaust valve 19;
This is a spark plug installed in a narrow position between the two.

The produced engines are tested and it is determined whether there are combustion abnormalities, ie, complete misfires or intermittent misfires.

This combustion abnormality occurs due to the gap of the spark plug 21 being too small, malfunction of the injector 15, or the like.

This combustion abnormality can be determined by whether or not the temperature has risen sufficiently after a certain period of time has elapsed since the engine was ignited.

That is, there is a difference in temperature rise between a cylinder that is working normally and a cylinder that is experiencing combustion abnormality. Therefore, after a certain period of time has elapsed after the engine has been ignited and started, the temperature near the exhaust port can be measured, and if the temperature rise is below a set lower limit value, it can be determined that combustion is abnormal.

Next, the combustion abnormality determination procedure according to the present invention will be explained in detail based on the flowchart of FIG.

The produced engine is transported to a test run facility and positioned. Prepare as many infrared thermometers 6 as there are cylinders, and set the sensor 7 of each thermometer 6 using a jig (not shown) at a position approximately 3 mm closer to the mating surface 9 of the exhaust manifold 5 with the cylinder head exhaust boat 3. . After the set is complete, temperature detection begins. Then, for each cylinder, the temperature is continuously detected for 1 second from the same point in time,
The average value is memorized. Then, ignite and start the engine. After 10 seconds have elapsed since the engine was started, the temperature is continuously detected for another 1 second, and the average value is stored. Then, the determiner 23 calculates the temperature difference between the average temperature before engine ignition and the average temperature after engine startup for each cylinder. Then, a comparison is made to see whether the temperature difference calculated for each cylinder is smaller or larger than a set lower limit value of the temperature difference. If the actual temperature difference is smaller than the lower limit value, this means that the temperature near the exhaust port has not risen sufficiently, and it is determined that there is a combustion abnormality in that cylinder.

When this determination is made, the alarm 25 issues an alarm to that effect. Further, if the actual temperature difference in each cylinder is larger than the lower limit value, it is determined that combustion is normal.

As explained above, according to the present invention, the infrared thermometer 6
is set for each cylinder, so it is easy to determine which cylinder among the plurality of cylinders has an abnormality. Furthermore, the infrared thermometer 6 can be set without having its sensor 7 come into contact with the test run engine, making the determination work easy. Furthermore, the infrared thermometer 6 can detect temperature instantaneously and with sufficient accuracy, and can determine combustion abnormality in each cylinder with sufficient accuracy.

As described in detail, according to the infrared temperature detection type combustion abnormality determination method of the present invention, the temperature near the exhaust port of each cylinder is detected by an infrared thermometer, and the temperature does not rise sufficiently by engine ignition. Since it is easily determined that there is a combustion abnormality, it is possible to instantly determine which cylinder has a combustion abnormality with sufficient accuracy, and without contacting the engine.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an apparatus used in an infrared temperature detection type combustion abnormality determination method according to an embodiment of the present invention, and FIG.
3 is a flowchart showing a determination procedure performed using the device shown in the figure. 3. Exhaust boat, 5. Exhaust manifold,
6. Infrared thermometer, 7. Sensor, 9. Matching surface, 2
3... Judgment device, 25... Alarm device.

Claims (1)

[Claims] An infrared temperature sensor is brought close to the exhaust port of each cylinder of an automobile engine, and if the detected temperature difference before and after engine ignition is less than a set lower limit value, it is determined that combustion is abnormal. Detection type combustion abnormality determination method.