JPH02146245A - Combustion variation detecting method of internal combustion engine - Google Patents

Abstract

PURPOSE:To carry out the detection of the combustion variation efficiently with a good adaptation by detecting the rotation speed of an internal combustion engine, finding the deviation of the angular speed in a specific period, and detecting the deviation as an element to indicate the combustion variation. CONSTITUTION:While the projection 101 of a crankshaft 1 and an electric pickup 2 in an engine are operated cooperatively, the rotation time of the crankshaft 1 in a desired angle is detected by a clock circuit 3, and the detected time is stored in registers 4 and 5. In such a way, the rotation angular speed (omega) of the internal combustion engine is detected. While the deviation of the angular speed per a specific time (DELTAomega=omega1-omega2) is found, the deviation (DELTAomega) is detected as an element to indicate the combustion variation. Consequently, from the variation of the angular speed, the generating torque and the combustion variation are detected, and a detection method with an excellent adaptation can be carried out efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting the operating state of an internal combustion engine, and more particularly to a method for detecting combustion fluctuations in an internal combustion engine.

[Conventional technology]

A known method for detecting the combustion state of an internal combustion engine is to detect the oxygen concentration in exhaust gas.

In this method, as described in US Pat. No. 3,738,341, an oxygen sensor is provided in the exhaust gas passage, and the combustion state is detected based on the output of this oxygen sensor.

[Problem to be solved by the invention]

By the way, according to the above-mentioned method, the information is accurate because it determines whether the exhaust gas is combusted at the stoichiometric air-fuel ratio state, but there are problems such as a delay in the flow of the exhaust gas and a lack of quick solubility. There is.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention is a method for detecting combustion fluctuations in an internal combustion engine, which detects the rotational angular velocity (ω) of the internal combustion engine, and detects the deviation of the angular velocity (Δω=ω1−ω2) per predetermined period.
) and detecting this angular velocity deviation Δω as a factor representing combustion fluctuation.

[Effect]

According to such a method, since combustion fluctuations are detected from the rotational angular velocity, it is possible to detect combustion fluctuations with high solubility.

〔Example〕

An embodiment of the present invention will be described below according to the open view, and as a specific example, a method of detecting engine rotational fluctuations and detecting engine combustion fluctuations will be presented.

As shown in FIG. 1, the angular velocity ω of the crankshaft varies from cycle to cycle due to combustion variations in the engine. In the case of a single cylinder, the angular velocity ω increases during the explosion stroke after a crank angle of 360 degrees. In the case of a four-cylinder engine, explosion occurs every cycle, so the angular velocity ω increases in the middle of the explosion stroke. As shown in FIG. 2, the average value ω of this angular velocity ω increases in proportion to the engine speed.

As shown in FIG. 3, the method for detecting this angular velocity ω is to make the protrusion 101 of the engine crankshaft 1 work together with the electric pickup 2, and use the clock circuit 3 to determine the time it takes for the crankshaft 1 to rotate by an arbitrary angle. is detected and registers 4 and 5
There is a way to remember the above times. crank 11il
The time it takes for I11 to rotate by a given rotation angle decreases as the number of rotations increases as shown in FIG. 2, so the angular velocity ω1. In order to improve the resolution of ω2, it is sufficient to increase the clock frequency of the clock circuit 3.

Using the configuration shown in FIG. 3, the angular velocity ω in FIG. 1 is obtained! , ω2 can be obtained. In an ideal state where combustion does not vary, the angular velocity deviation Δω=ω2−ω1 is equal for each cycle. As the combustion fluctuation increases, Δω differs for each cycle. As the engine speed increases, Δω becomes smaller due to the influence of the inertia of the movable parts.

At this time, when the engine speed is high, the opening angular velocity ωl and the angular velocity ω2 of several cycles can be integrated.

Now, the relationship between torque T and angular velocity ω is 22, ■ = engine inertia T: Torque generated by the engine TB: Engine load torque t: Elapsed time It becomes like this.

As shown in Fig. 4, ...(6) and ■ n ...(4). Therefore, now any to waiting time (ω, −
ω2) is integrated, and the integrated value is equal to T and is not affected by the rotation speed.

becomes. On the other hand, by integrating using equation (3), T o is obtained.

As shown in FIG. 3, in the method of determining ω by fixing the time 411 for the crank angle to rotate by an arbitrary angle.

Then ω l =−... (8) ω 1 is obtained. Therefore, if we integrate to time tω now, we get Kt.

Ktoω ω+Δωl Therefore, it is possible to detect combustion fluctuations from torque fluctuations, that is, angular velocity fluctuations.

FIG. 5 shows changes in the angular velocity deviation Δω during acceleration. Moreover, FIG. 6 shows the change in Δω when the rotational speed is high. here.

Approximately, it becomes. Further, since ω2-ω1=(Δω2+Δω, 1), ω2-ωl can be obtained by integrating tω over an arbitrary to time and multiplying by a value. Furthermore, T = (ωz - (Ill) Deviation Δωl=ω2-ω1.-Δω2=ω2
＾－ω! What is the relationship between ^?

That is, integrate tω over an arbitrary to time.

By multiplying by ω2, information regarding the torque is obtained.

So, ω (Δ ω Ω − Δ ω2) = ΔT
...(15) Here, ω is the average value of ω.

Now, when the throttle valve opening changes over time as shown in FIG. 7, the generated torque T also changes accordingly, and the deviation Δω of the angular velocity also changes in accordance with the change in r. Therefore, with only information on the angular velocity deviation Δω, it is not possible to determine whether the angular velocity deviation Δω is changing due to combustion fluctuations or whether the angular velocity deviation Δω is changing in response to changes in the throttle valve opening. It turned out there was a problem. In the present invention, this discrimination is attempted by the means described below.

That is, in this determination method, only the combustion variation is extracted by comparing the actual angular velocity deviation Δω and the virtual angular velocity deviation ΔωP. Grid, throttle valve opening,
Alternatively, input information such as air amount and intake pressure into a computer, calculate the torque T that the engine should generate for the throttle valve opening, and based on this, the virtual angular velocity deviation Δω
P is calculated and compared with the deviation Δω of the actually measured angular velocity. Therefore, Δω−ΔωP becomes the combustion fluctuation amount. In this way, the true combustion variation can be extracted. As shown in FIG. 8, the difference between the virtual angular velocity deviation ΔωP and the actually measured angular velocity deviation Δω is not affected by the throttle valve opening and shows a torque fluctuation ΔT. Now X=Δω−Δ
When ωP is assumed, X=o when there is no torque fluctuation based on combustion fluctuation. However, the deviation of the virtual angular velocity ΔωP
If it is estimated to be small, it will always be X>0. Also,
If the deviation ΔωP of the virtual angular velocity is estimated to be large, it will always be X × O. In this case, the average value X of X for a certain time can be determined, and XX can be taken as the torque fluctuation value.

In this way, it is a great advantage of microcomputer control that information regarding combustion fluctuations can be accurately grasped even in a transient state where the amount of air changes from moment to moment. If X−X is large, there is a problem in the control of the control vector (air-fuel ratio 2 ignition timing, etc.), but it is likely that there is a problem in the engine itself. Therefore, x-
An operation is performed to correct the control vector from the information of X. X-
If X is large, for example, the air-fuel ratio is too large, so the air-fuel ratio control device is corrected. If X-X does not become smaller even after a certain amount of correction, it is a problem with the engine itself, and an alarm is issued to the outside. Amendment 2 judgment above.

The alarm operation can be performed by a microcomputer.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to detect generated torque and combustion fluctuations from fluctuations in angular velocity, and a detection method with excellent quick solubility can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between crank angle and angular velocity, Figure 2 is a diagram showing the relationship between rotational speed and average angular velocity, Figure 3 is a block diagram of the rotational speed detection device, Figure 4 is a diagram showing the relationship between angular velocity, and Figure 5 is a diagram showing the relationship between rotational speed and average angular velocity. Figure 6 and Figure 6 are relationship diagrams between time and angular velocity, Figure 7 is a relationship diagram between time and deviations in throttle valve opening, torque, and angular velocity, and Figure 8 is actual measured values of deviations in time, throttle valve opening, and angular velocity. , a diagram of the relationship between virtual values and their deviations.・・Crankshaft ・・・Electric pickup

Claims (1)

[Claims] 1. In the combustion fluctuation detection method of an internal combustion engine, the rotational angular velocity (ω) of the internal combustion engine is detected, the angular velocity deviation (Δω = ω_1 − ω_2) per predetermined period is determined, and this angular velocity deviation Δω is used to determine the combustion fluctuation. 1. A method for detecting combustion fluctuations in an internal combustion engine, characterized in that the combustion fluctuations in an internal combustion engine are detected as an expression factor.