JPH0681708A - Controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a controller for an internal combustion engine, the cost of which has been reduced by simplifying the constitution of a sensor system. CONSTITUTION:A controller for an internal combustion engine is provided with a crank angle sensor 7 which issues a pulse-shaped reference cycle signal thetasynchronizing with rotation of the internal combustion engine, a control timing calculating part 10 which calculates control timing of the internal combustion engine on the basis of a pulse edge of the reference cycle signal, a misfire detecting part 10 which determines a misfire of the internal combustion engine on the basis of a time rate corresponding to a pulse cycle next to the reference cycle signal respectively, and a noise eliminating means 10 which eliminates a noise overlapped on the reference cycle signal when the time rate shows an abnormal value, so that the reference cycle signal for control and the reference cycle signal for the misfire detection are commonly used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine controller for calculating a control timing based on a reference cycle signal synchronized with the rotation of an internal combustion engine and detecting a misfire. The present invention relates to an internal combustion engine control device that realizes cost reduction by sharing a reference period signal for detecting misfire.

[0002]

2. Description of the Related Art In general, misfire of an internal combustion engine directly pollutes the atmosphere by releasing unburned gas and damages the catalyst due to an abnormal temperature rise caused by the reaction between the unburned gas and a catalyst for treating exhaust gas. Therefore, it is necessary to detect it as soon as possible and repair the faulty part that causes misfire.

Conventionally, a pulsed reference period signal and a cylinder identification signal corresponding to the crank angle position are generated in synchronization with the rotation of the internal combustion engine, and the internal combustion engine is controlled based on the control reference period signal. BACKGROUND ART An internal combustion engine control device that detects a misfire based on a time ratio of a predetermined section of a reference period signal for detecting a misfire or a change in acceleration of the time ratio is well known.

Normally, the crank angle position indicated by the control reference cycle signal corresponds to the ignition timing of the internal combustion engine, and is used as a control reference for the ignition timing or the fuel injection timing and is used for detecting the engine speed. Also, the predetermined section used for the time ratio calculation of the reference period signal for misfire detection is
For example, the pulse period section before and after the top dead center (TDC) is selected.

A control timing calculating section for calculating and controlling the ignition timing and the fuel injection timing based on the operating state and the control reference cycle signal, and a misfire detection for performing time detection and time ratio calculation based on the misfire detection reference cycle signal. The unit is included in the ECU formed of a microcomputer.

The ECU uses the TD of the reference period signal for detecting misfire.
The time ratio of the crank angle section before and after C is compared with a predetermined value, and if the time ratio shows an abnormal value, it is determined that there is a misfire, and if it is within a predetermined range, it is determined that it is normal. The time ratio at this time is obtained from, for example, the current value and the previous value of each time for each predetermined adjacent section, and the previous value of both section cycles.

However, as described above, the crank angle position that is the control reference for the ignition timing and the like and the ideal crank angle position for calculating the time ratio for misfire determination do not match, so the control reference cycle It is necessary to separately generate the signal and the reference period signal for detecting the misfire. Therefore, a large number of crank angle sensor systems are installed, which complicates the structure and increases the cost.

On the other hand, a ring gear is provided on the transmission (transmission) side of the engine, and it is conceivable to provide an electromagnetic pickup on the ring gear as a reference period signal generating means for control or misfire detection. Figure 6
Is a ring gear having magnetic protrusions evenly spaced along the outer circumference.
6B shows a configuration of a reference period signal generating means in which 6B is provided on the crankshaft 4 and a pulse signal is obtained from the electromagnetic pickup 7B.

FIG. 7 is a waveform diagram showing a pulse-shaped reference period signal θB obtained from the electromagnetic pickup 7B, and the pulse interval is 180 ° in crank angle. However, as is apparent from FIG. 7, the reference period signal θB obtained from the electromagnetic pickup 7B has a sharp edge and a large amplitude at high rotation, but has a dull edge and a small amplitude at low rotation. Therefore, when the engine speed is low, for example, the highly accurate crank angle position required for misfire detection cannot be determined, and misfire may be erroneously detected.

If the required signal level is to be obtained even at a low speed, it is not practical because it is necessary to increase the diameter of the ring gear 6B to increase the angular velocity. Also, as the reference cycle signal θB, the electromagnetic pickup 7B and the ring gear 6B
Since the pulse signal having a short period is obtained when the magnetic projections of (1) and (2) face each other, it is clear that the noise resistance is low.

[0011]

As described above, the conventional internal-combustion-engine control device is provided with individual sensor systems for obtaining the reference period signals for control and misfire detection, which leads to an increase in cost. There was a problem. Further, even if the electromagnetic pickup 7B is arranged opposite to the ring gear 6B coaxial with the crankshaft 4, a reference period signal having sufficient accuracy cannot be obtained, which is not practical.

The present invention has been made to solve the above problems, and controls the internal combustion engine by reducing the cost by sharing the control reference period signal and the misfire detection reference period signal. The purpose is to obtain the device.

[0013]

SUMMARY OF THE INVENTION An internal combustion engine control apparatus according to the present invention is an internal combustion engine based on a crank angle sensor for generating a pulse-shaped reference period signal synchronized with the rotation of an internal combustion engine and a pulse edge of the reference period signal. When the control timing calculation unit that calculates the control timing of the engine, the misfire detection unit that determines the misfire of the internal combustion engine based on the time ratio corresponding to each adjacent pulse period of the reference period signal, when the time ratio shows an abnormal value And a noise removing means for removing the noise superimposed on the reference period signal.

[0014]

According to the present invention, the time ratio is calculated based on the reference period signal which is the reference for controlling the internal combustion engine obtained from the crank angle sensor, the misfire is determined, and the noise removal process is performed.

[0015]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a block diagram showing a first embodiment of the present invention,
Reference numeral 4 is a crankshaft similar to that described above. Reference numeral 1 is an engine which is a main body of an internal combustion engine, and 2 is a transmission provided on the rear side 1b of the engine 1.

Reference numeral 3 denotes a cam shaft which is synchronized with the rotation of the engine 1, which is interlocked with the crank shaft 4 via a timing belt and has a rotation speed which is half that of the crank shaft 4. Reference numeral 5 denotes a distributor provided on the camshaft 3 for distributing electric power for ignition to a plurality of cylinders.

Reference numeral 6 is a rotary plate provided on the crankshaft 4 on the front side 1a of the engine 1, and has, for example, a plurality of slits along the rotational direction. Reference numeral 7 denotes a crank angle sensor arranged to face the rotary plate 6, and is composed of, for example, a photocoupler, and generates a pulse-shaped reference period signal θ synchronized with the rotation of the internal combustion engine, that is, the engine 1. Although not shown,
The camshaft 3 is provided with a sensor system having the same configuration as the rotary plate 6 and the crank angle sensor 7, and generates a cylinder identification signal C associated with a specific cylinder.

Reference numeral 8 is an air flow sensor for detecting the intake air amount A to the engine 1, and 9 is an injector for injecting fuel into each cylinder of the engine 1. Reference numeral 10 denotes an ECU including a microcomputer, which controls fuel injection and ignition timing of the internal combustion engine and detects misfire based on the intake air amount A representing the operating state of the internal combustion engine, the cylinder identification signal C, the reference cycle signal θ, and the like. To do.

The ECU 10 controls the fuel injection and ignition timing of the internal combustion engine based on the pulse edge of the reference cycle signal θ, and the time ratio corresponding to each adjacent pulse cycle of the reference cycle signal θ. The ignition signal F for the distributor 5 is provided with a misfire detection unit that determines a misfire of the internal combustion engine based on the above, and a noise removal unit that removes noise superimposed on the reference cycle signal θ when the time ratio shows an abnormal value. And a fuel injection signal J for the injector 9 and a misfire determination signal E at the time of misfire determination. Reference numeral 11 is an alarm lamp that is driven by the misfire determination signal E to notify the misfire.

In FIG. 1, a control timing calculation unit in the CPU 12 of the ECU 10 operates based on signals obtained from various sensors such as the engine speed based on the reference cycle signal θ and the intake air amount A from the air flow sensor 8. Is calculated,
The ignition signal F for the distributor 5 is generated to control the ignition timing.

Further, the misfire detecting section in the CPU 12 of the ECU 10 judges the misfire of the internal combustion engine from the time ratio of the reference cycle signal θ for each pulse cycle, and generates the misfire judgment signal E when the misfire is judged. FIG. 2 is a timing chart for explaining the misfire detection operation, and T1 to T4 are periods (rotation periods) of rising pulse edges of the reference period signal θ corresponding to the # 1 to # 4 cylinders, respectively. The fall timing of the ignition signal F for each cylinder, that is, the ignition timing is calculated with reference to the crank angle position of the rising edge of the reference period signal θ.

The cylinders # 1 to # 4 are identified by the cylinder identification signal C related to the # 1 cylinder, and then # 1 → # 3.
→ # 4 → # 2 cylinders are identified in this order. Therefore, if the pulse periods T1 to T4 of the reference period signal θ are measured for each cylinder, it is possible to determine the occurrence of misfire in the corresponding cylinder when the pulse period becomes longer than that in the other cylinders. In the example of FIG. 2, since T4> T1≈T2≈T3, it can be seen that the # 4 cylinder has misfired.

When the misfire is not judged, the ECU 10 does not generate the misfire judgment signal E but only performs the normal ignition timing control and the like, and when the misfire is judged, the misfire judgment signal indicating the misfire of the cylinder to be controlled. E is generated and the alarm lamp 11 is turned on, and the occurrence of misfire is stored in the storage means. As a result, the driver immediately recognizes the occurrence of misfire and stops the operation, and the outflow of unburned gas is prevented.

On the other hand, the noise removing means in the CPU 12 of the ECU 10 individually measures the periods of the H level section and the L level section of the reference cycle signal θ, and determines that the cycle is noise when it is shorter than a predetermined time. FIG. 3 is a timing chart for explaining the noise removal processing operation, where θ ′ is a reference period signal on which noise is superimposed and N1 to N3 are noises on the reference period signal θ.

In this case, since the cycle of the L level section due to the noise N1 is shorter than the predetermined time, the L level pulse N1
Is determined to be noise and is corrected to a regular reference period signal θ. Similarly, the L-level noise N2 and the H-level noise N3 are determined as noise and are corrected to the normal reference period signal θ. At this time, each noise N2 and N
Immediately after 3, there is a short pulse of opposite polarity, but when short pulses are continuously detected, the algorithm is set to determine the first short pulse as noise.

In this way, 1 from the crank angle sensor 7
Based on one reference cycle signal θ, misfire detection can be performed as well as control of the internal combustion engine. In this case, each cycle T
The crank angle position serving as the measurement reference of 1 to T4 coincides with the control reference and cannot be said to be ideal. However, since the cycle measurement reference is in the vicinity of the control reference of the ignition signal F, no particular trouble occurs. .

Further, as is apparent from FIG. 4, the reference period signal θ obtained from the crank angle sensor 7 maintains a highly accurate pulse waveform even at low rotation unlike the case of the electromagnetic pickup (FIG. 7). Therefore, the cycle measurement can be performed with high accuracy even when the engine 1 is started.

Further, the sensor system can be attached to the crankshaft 4 on the front side 1a of the engine 1 relatively easily because the transmission 2 is not arranged. For example, the sensor system may be the central part or the rear side of the engine 1.
If it is attempted to mount it on 1b, it is necessary to form a sensor mounting hole in the crankcase or the mission case, and the sensor system is required to have heat resistance and stain resistance, which is not practical.

Further, when the sensor system for generating the reference period signal is provided on the cam shaft 3, it goes without saying that the detection accuracy is lowered because the cam shaft 3 is rotating via the timing belt.

Example 2. Although the rotary plate 6 having the slit and the crank angle sensor 7 including the photo coupler are used as the sensor system in the first embodiment, a sensor system including the Hall IC may be used. FIG. 5 is a side view showing a Hall type crank angle sensor. 6A is, for example, a rotary plate having magnets protruding from each other at a predetermined interval, and 7A is a Hall IC arranged to face each protruding magnet on the rotary plate 6A. Is a crank angle sensor. Also in this case, the reference period signal θ similar to that in FIG. 2 can be generated, and the same effect as the above can be obtained.

[0031]

As described above, according to the present invention, the crank angle sensor for generating the pulse-shaped reference period signal synchronized with the rotation of the internal combustion engine, and the control timing of the internal combustion engine based on the pulse edge of the reference period signal. A control timing calculation unit that calculates a misfire detection unit that determines misfire of the internal combustion engine based on the time ratio corresponding to each adjacent pulse cycle of the reference cycle signal, and the reference cycle signal when the time ratio shows an abnormal value. A noise removing means for removing the noise superimposed on the sensor is provided, and the reference period signal for control and the reference period signal for misfire detection are shared, so that the configuration of the sensor system is simplified and the cost is reduced. There is an effect that an internal combustion engine control device that achieves down is obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a timing chart showing a misfire detection operation according to the first embodiment of the present invention.

FIG. 3 is a timing chart showing a noise removing operation according to the first embodiment of the present invention.

FIG. 4 is a timing chart showing a waveform change of the reference period signal with respect to the rotation speed according to the first embodiment of the present invention.

FIG. 5 is a side view showing a configuration of a crank angle sensor according to a second embodiment of the present invention.

FIG. 6 is a side view showing a configuration example of a crank angle sensor of a conventional internal combustion engine control device.

7 is a waveform diagram showing a reference period signal obtained by the crank angle sensor of FIG.

[Explanation of symbols]

 1 engine 4 crankshaft 6 rotating plate 7 crank angle sensor 10 ECU 11 alarm lamp θ reference cycle signal E misfire determination signal F ignition signal J fuel injection signal T1 to T4 pulse cycle N1 to N3 noise

Claims (1)

[Claims] 1. A crank angle sensor for generating a pulse-shaped reference cycle signal synchronized with the rotation of an internal combustion engine, and a control timing calculation section for calculating a control timing of the internal combustion engine based on a pulse edge of the reference cycle signal. A misfire detection unit that determines misfire of the internal combustion engine based on a time ratio corresponding to each adjacent pulse period of the reference period signal, and is superimposed on the reference period signal when the time ratio shows an abnormal value. An internal combustion engine control device comprising: a noise removing unit that performs a noise removing process.