TWI498536B - Method and device for diagnosing misfire in single-cylinder engine - Google Patents

Description

Diagnostic method for single cylinder engine ignition failure and diagnostic tool using the same

A method for diagnosing whether a single-cylinder engine fails to ignite and a diagnostic device using the same, in particular, the engine is in the running power stroke, and uses the relationship between the instantaneous rotational speed of the crankshaft connecting the engine and the change of the average rotational speed to determine whether the engine has an ignition failure The method and the diagnostic tool using the method.

The pollution regulations imposed by the countries in the world are becoming more and more stringent. The vehicle must be equipped with an On Board Diagnostic (OBD) system to detect component degradation or failure before the exhaust gas exceeds the standard. This allows the owner to decide whether or not to maintain the components, thus ensuring that the exhaust emissions of their vehicles meet the standards. However, the current locomotive is not required to install an OBD system.

The technology for the development of the OBD system of the automobile has been quite mature. However, since the operating conditions of the locomotive of the multi-cylinder engine and the single-cylinder engine are different, and the arrangement of the air pollution control systems of the two systems is also different. Therefore, if the locomotive needs to install the OBD system, it needs to be discussed and researched according to the operation of the locomotive, in order to develop a set of OBD system suitable for locomotives.

At present, there are five methods for igniting the ignition failure of a car: detecting the change of the crankshaft speed, detecting the spark plug ion current, detecting the cylinder pressure, detecting the exhaust pressure, and detecting the oxygen content in the exhaust pipe. None of these methods have been applied to the ignition failure diagnosis method on the locomotive.

The inventors have in view of various methods for previously testing the ignition failure of automobiles, and have not applied to the ignition failure diagnosis method on the locomotive, and the extensive use of the locomotive in the Asian region does require a method for verifying the ignition failure of the locomotive. Avoid the environmental pollution caused by the exhaust gas emitted by the locomotive after the ignition failure. Accordingly, it is an object of the present invention to provide a single The diagnosis method of the ignition failure of the cylinder engine and the diagnostic tool using the method are applied to the engine of the single cylinder of the locomotive to diagnose whether or not the ignition failure occurs.

In the above-mentioned method for the ignition failure diagnosis of automobiles, the method of using the spark plug ion current requires an additional sensor and a special spark plug that can induce the ion current in the combustion chamber, which increases the cost. In addition, in the method of detecting the cylinder pressure, an expensive pressure gauge is additionally installed. Further, in the method of detecting the exhaust pressure, as in the method of detecting the cylinder pressure, it is also necessary to additionally install an expensive pressure gauge. Finally, in the method of detecting the oxygen content in the exhaust pipe, an oxygen sensor is additionally installed, wherein the oxygen sensor has a limited operating temperature range, and the ignition failure cannot be distinguished by the ignition alone. Caused by the system or the fuel injection system, when the throttle suddenly changes or the fuel system concentration increases or the oil is cut off, misjudgment is easy to occur, and the diagnostic reliability is not high.

However, in the method for detecting the change of the crankshaft speed, the signal output by the existing crankshaft position sensor of the locomotive can be used for diagnosis, so that the engine can be effectively diagnosed whether the ignition failure occurs without additional cost of other hardware.

The invention provides a specific method for detecting whether a single cylinder engine is ignited or not by detecting a change in a crankshaft speed in a power stroke of an engine operation, wherein the crankshaft is connected to a single cylinder engine, and the engine generates a reciprocating cycle to drive the crankshaft to rotate by one revolution. The method consists of the following steps:

1. Calculating a plurality of angular velocities of the crankshaft that are rotated in an angular interval in one of the cycles of the reciprocating cycle.

2. Calculate the average angular velocity of the plurality of speeds.

3. Calculating the average angular velocity minus the last angular velocity of the plurality of angular velocities produces a first difference.

4. Determine whether to initiate the ignition failure diagnosis via the first difference.

5. Calculating an average angular velocity of the plurality of angular velocities in which the crankshaft is rotated in the angular interval of the previous cycle of the cycle minus the average angular velocity to produce a second difference.

6. Calculating a first angular velocity of the plurality of angular velocities at which the crankshaft is rotated within the angular interval of the previous cycle of the cycle minus a first angular velocity of the plurality of angular velocities to produce a third difference.

7. Calculating the second difference plus the third difference produces an RI value.

8. Determine if the RI value is greater than an ignition failure threshold.

Wherein, the steps can be repeated until an ignition failure occurs within the engine.

The method of determining, by the first difference, whether to initiate the ignition failure diagnosis is whether the first difference is greater than or equal to 0.

The manner of generating the ignition failure threshold includes: using a means to cause the engine to fail multiple times; recording a plurality of RI values of the ignition failure; recording the plurality of RI values without ignition failure; The intermediate value of the minimum of the RI values for which the ignition failure has occurred and the maximum of the RI values for which the ignition failure has not occurred is calculated. It should be noted that the use of a means to cause the engine to fail multiple times and to record a plurality of RI values without ignition failure is not sequentially dependent.

Wherein, the reciprocating cycle of the engine sequentially includes an intake stroke, a compression stroke, a power stroke and an exhaust stroke, and the angle interval in which the diagnosis engine fails to fire is preferably within an angular interval of the crankshaft after the end of the compression stroke.

A diagnostic apparatus can be prepared by the method of the present invention, and the diagnostic apparatus can be disposed in a locomotive to diagnose whether the locomotive has an ignition failure.

Among them, the diagnostic device can be combined with a mechanism for storing the ignition failure fault code and a fault indicator light to make the locomotive have a complete OBD system.

In addition, the diagnostic device may additionally include an oxygen sensor to determine whether the ignition failure is caused by a fuel injection or an ignition system by detecting the amount of oxygen in the exhaust gas.

C1, C2, C3, C4, C5, C6‧‧‧ calculation steps

J1, J2‧‧‧ judgment steps

The first picture shows the architecture of the ignition failure generator.

The second figure is an architectural diagram for verifying the experiment of the present invention.

The third figure is the measurement interval for the best diagnosis of the present invention.

The fourth figure is a flow chart of the steps of the present invention.

The fifth graph is a graph showing the results of the experiment of the present invention.

The sixth graph is a graph showing the results of the experiment of the present invention.

The embodiments of the present invention will be described in more detail below with reference to the drawings and the <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt;

The method provided by the present invention actually operates and records the effects of using the present invention by utilizing a new CYGUNS-X electronic jet locomotive produced by YAMAHA Locomotive Company. Among them, the recording environment of the experiment is that the locomotive has three conditions of idle speed, constant speed 50Km/h no load and constant speed 50Km/h load, and the ignition failure generator is used to make the engine of the locomotive generate 5% ignition failure. In addition, the engine control unit (ECU) of the locomotive is retained, so as not to change the control strategy of the original engine, so that the locomotive operates under the conditions set by the original engine.

By using an ignition failure generator as a means for igniting the locomotive, it is verified that the present invention can effectively diagnose the occurrence of ignition failure in the event of ignition failure of the locomotive. Wherein, as shown in the first figure, it is an architectural diagram of the ignition failure generator.

A controller can receive the gear signal of the crankshaft on the locomotive, and store an ignition failure generating program. After the controller calculates the gear signal and the ignition failure generating program, an ignition failure signal can be outputted to a processing circuit, and the processing circuit can The spark plug on the locomotive will not be ignited, so that the locomotive will fail to ignite.

In order to diagnose the ignition failure of the crankshaft on the locomotive engine, as shown in the second figure, the locomotive is connected to an arithmetic unit, which is then connected to a personal computer (PC). Wherein, the locomotive outputs the gear signal, the MAP signal and the gear speed signal to the operator, and the operator performs the operation on the signal data and transmits and exchanges signals with the PC via the UART, so that the crank angular velocity and the like can be displayed on the PC as a graph. .

Before the experimental results are shown, the following is a brief description of the single-cylinder four-stroke engine, and explains the method for diagnosing ignition failure that the present invention contemplates based on the characteristics of a single-cylinder four-stroke engine.

In a single-cylinder four-stroke locomotive engine, a complete actuating reciprocating cycle has four strokes and will drive the crankshaft two turns (720 degrees). The four strokes are respectively the intake stroke, the compression stroke, the power stroke and the exhaust stroke, wherein each stroke of the crankshaft is rotated by 180 degrees, namely: intake stroke (0 degrees to 180 degrees); compression stroke (180 Degree to 360 degrees); power stroke (360 degrees to 540 degrees); exhaust stroke (540 degrees to 720 degrees).

At the end of the compression stroke, the spark plug is ignited to produce a pressure explosion and the power stroke begins. (The crankshaft begins to turn a second turn) and causes the crankshaft to produce angular acceleration. Since the ignition failure causes the power stroke to not generate angular acceleration, the power stroke is the best time to diagnose whether the engine has an ignition failure by using the crankshaft speed. After the crankshaft starts to rotate 90 degrees, the angular acceleration will begin to decrease. Therefore, the crankshaft can diagnose the ignition failure within 0 to 90 degrees of the start of the power stroke.

Please refer to the third figure, which is a schematic diagram of the optimal angle interval for diagnosing ignition failure. The gear on the crankshaft rotates in a clockwise direction, and the highest point is just the moment when the piston in the engine starts the power stroke (the moment when the compression stroke is completed), so it is called the compression top dead center (referred to as the top dead center). After compressing the upper point, any angle interval between 0 degrees and 90 degrees can be taken as the measurement interval.

The steps of the diagnostic method of the present invention are illustrated in the fourth figure, wherein the operator shown in the second figure uses this step to perform an operation for diagnosing whether or not an ignition failure occurs.

The calculating step C1 is to calculate a plurality of angular velocities in the angular range of the crankshaft after the top dead center rotation, wherein the calculation method is that the angular velocity of the tooth to the lower ulnar is calculated every time a tooth passes, so that a plurality of angular velocities ( ω _{m are obtained)} ), m is the number of teeth, the formula is as follows:

The calculating step C2 is to calculate the average angular velocity ( ω _{mean , m} ) of the equiangular velocity in the step C1, and the calculation formula is as follows (the equal angular velocity is obtained by calculating the angular velocity of the eight teeth in this embodiment):

The calculation step C3 calculates the value generated by the step C2 minus the last angular velocity, and generates a first difference ( misfire enable condition _m ) as follows:

The determining step J1 is preferably set to determine whether the first difference is greater than or equal to zero. When the first difference is greater than or equal to 0, it is calculated whether or not an ignition failure is generated.

The calculating step C4 is to calculate the average angular velocity of the plurality of angular velocities extracted by the crankshaft in the same angular interval from the previous cycle minus the calculation result of the calculating step C2, and generate a second difference ( diffω _{mean , m} ), which is calculated as follows : diffω _mean , _m = ω _mean , _{m -1} - ω _mean , _m

The calculating step C5 is to calculate a first angular velocity of the plurality of angular velocities captured by the crankshaft in the same angular interval in the previous cycle minus the first angular velocity of the equal angular velocity in the cycle to generate a third difference ( diffω) _m ), the formula is as follows:

The calculation step C6 is to add the calculation results of C4 and C5 to generate an RI value, and the calculation formula is as follows: RI = diffω _m + diffω _mean , _m

Finally, the determining step J2 determines whether the RI value is greater than an ignition failure threshold, and if the ignition failure threshold is greater than the ignition failure threshold, the engine is determined to have an ignition failure.

The steps illustrated in the fourth figure above may be repeatedly performed.

It should be noted that the ignition failure threshold is a value developed by the engine at different speeds, and is obtained by using the engine to perform ignition failure at each speed and load. The manner of obtaining this value includes: using the ignition failure generator to cause the engine to fail multiple times; recording a plurality of RI values for which ignition failure has occurred; recording the plurality of RI values for which ignition failure has not occurred; and calculating the The intermediate value of the minimum of the RI values of the ignition failure and the maximum of the RI values of the ignition failures, which is the ignition failure threshold. Wherein, the RI value of the plurality of non-ignition failures may be recorded before the engine fails to generate a plurality of ignition failures by using the ignition failure generator.

In the embodiment of the experiment of the present invention, an ignition failure threshold value is calculated in the above manner at an idle speed and a constant speed of 50 Km/h.

The following is an illustration of the ignition failure diagnostics generated in the PC when using the ignition failure generator shown in the first figure as a means of generating ignition failure and the experimental architecture as shown in the second figure.

Please refer to the fifth figure for the result of recording in the PC via the arithmetic unit in the case of the locomotive engine running at idle speed. As can be seen from the figure, when the ignition failure generator causes the spark plug on the locomotive to not ignite and outputs the ignition failure signal, the angular velocity and the average angular velocity instantaneously decrease. The operator detects that the RI value calculated by the speed drop of the crankshaft increases instantaneously and is greater than the ignition failure threshold value. When the RI value is greater than the ignition failure threshold value, the engine is determined to have an ignition failure.

Please refer to the sixth figure for the results recorded in the PC via the arithmetic unit at a fixed speed of 50Km/h. As can be seen from the figure, when the ignition failure generator causes the spark plug on the locomotive to not ignite and outputs the ignition failure signal, the angular velocity and the average angular velocity instantaneously decrease, and the arithmetic unit detects the instantaneous RI value calculated by the speed drop of the crankshaft. Increasing and greater than the ignition failure threshold, when the RI value is greater than the ignition failure threshold, the engine is determined to have an ignition failure.

The inventors conducted a total of three experiments on ignition failure diagnosis, namely: engine idle running (Experiment 1), engine fixed speed 50Km / h no load operation (Experiment 2) and engine fixed speed 50Km / h load operation (Experiment 3 ). The experimental results show that the ignition failure and the accuracy of the ignition failure are accurately diagnosed, 100% for both experiments 1 and 2, and 99% for the third experiment. The experimental results prove that the present invention can effectively detect the ignition failure of the single cylinder engine.

The method claimed by the present invention can be written as a program and matched with a hardware to form a diagnostic device, which can be connected to a locomotive having a single-cylinder four-stroke engine, and the original crankshaft gear and position sensor on the locomotive. To diagnose whether the locomotive has failed ignition.

In addition, the diagnostic device can refer to the car ignition failure storage fault code and the mechanism of the fault indicator light, so that the locomotive has a complete OBD system like a car.

In addition, the diagnostic device may additionally include an oxygen sensor, and by detecting the amount of oxygen in the exhaust gas, it is determined that the cause of the ignition failure is a problem of fuel injection or ignition system, thereby making the OBD system more perfect.

It should be noted that the vehicles after the current five-phase environmental protection regulations (including the fifth phase) of the locomotive are equipped with an oxygen sensor. The diagnostic device may additionally include an oxygen sensor as described above. After the five-phase environmental protection regulations in the market, the locomotive with oxygen sensor is used.

The above is only a preferred embodiment for explaining the present invention, and is not intended to limit the present invention in any way, and any modifications or alterations to the present invention made in the spirit of the same invention. All should still be included in the scope of the intention of the present invention.

C1, C2, C3, C4, C5, C6‧‧‧ calculation steps

J1, J2‧‧‧ judgment steps

Claims (6)

A single cylinder engine ignition failure diagnosis method, the method is applied to a single cylinder engine connected with a crankshaft, the engine can generate a reciprocating cycle and drive the crankshaft to rotate at a revolution number, which comprises: measuring the crankshaft in a reciprocating cycle One of the plurality of angular velocities rotated in an angular interval; calculating an average angular velocity of the plurality of angular velocities; calculating the average angular velocity minus the last angular velocity of the plurality of angular velocities to generate a first difference; The value determines whether the ignition failure diagnosis is initiated; calculating an average angular velocity of the plurality of angular velocities in which the crankshaft rotates in the angular interval of the previous cycle of the cycle minus the average angular velocity to generate a second difference; calculating the crankshaft in the cycle The first angular velocity of the plurality of angular velocities rotated by the previous cycle in the angular interval minus the first angular velocity of the plurality of angular velocities produces a third difference; calculating the second difference plus the third difference Generating an RI value; and determining whether the RI value is greater than an ignition failure threshold. The method for igniting a single cylinder engine ignition failure according to claim 1, wherein the method of determining whether to initiate the ignition failure diagnosis via the first difference is whether the first difference is greater than or equal to zero. The method for igniting a single cylinder engine ignition failure according to any one of claims 1-2, wherein the ignition failure threshold is generated by: Using an ignition failure generator to cause the engine to fail multiple times; recording a plurality of RI values for which ignition failure has occurred; recording a plurality of RI values for which no ignition failure has occurred; and calculating the RI for which the ignition failure has occurred The minimum of the values and the median of the maximum of the RI values for which no ignition failure occurred. A diagnostic apparatus for diagnosing whether the locomotive has an ignition failure by using a method as described in claim 1 of the invention. For example, the diagnostic device described in claim 4 of the patent application, together with the mechanism for storing the ignition failure fault code and a fault indicator light, enables the locomotive to have a complete OBD system. The diagnostic device of any of claims 4-5, wherein the diagnostic device additionally has an oxygen sensor.