JPS608446A - Control device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To eliminate a load sensor or render an engine controllable even in an abnormal operation of the sensor, by processing a signal from a speed sensor by a speed difference and a statistical operation to produce a load signal, and utilizing the load signal for control of an ignition timing or a fuel injection quantity. CONSTITUTION:A basic advance value thetai is computed from an average engine rotational speed N as measured, and a rate of change dN/dt of the rotational speed N is determined. If the rate of change is within a fixed value, it is judged that an engine is under an ordinary condition, while if it is over the fixed value, it is judged that the engine is under a transitional condition. When the engine is under the transitional condition, the basic advance value thetai is defined as an ignition timing theta and is fed to an ignition drive circuit 15. When the engine is under the ordinary condition, a rotational speed N1 at the moment when a first cylinder reaches a top dead center is read. Reaching CA at 90 deg. after the top dead center, a rotational speed N2 is read to compute the difference DELTAN between both the rotational speeds N1 and N2. The DELTAN is added to a variable SUM to count up a variable M by one. Next, when a statistical processing loop reaches a prescribed frequency, an average value DELTANave of the difference DELTAN is computed, and a data from a compensated advance map is read out to compute a load compensated advance thetac and then generate the ignition timing theta.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an internal combustion engine, and more particularly to a device that detects and controls the load of the engine using a signal from a speed sensor that detects the rotational speed.

Conventionally, the ignition timing or fuel injection amount of an internal combustion engine has been calculated by a computer based on signals from load sensors such as an intake air amount sensor and intake negative pressure sensor, and a speed sensor that detects the rotational speed of the engine. Ta.

Therefore, there is a problem that an expensive load sensor is required or that control cannot be performed when the load sensor is abnormal.

This invention was made in view of the above problem, and is the 12th invention.
As shown in the figure, a signal indicating the engine load is created by processing the speed sensor signal by speed difference calculation and statistical calculation.
The purpose of this invention is to use this to control the ignition timing or fuel injection amount to enable control even when a load sensor is unnecessary or when the load sensor is abnormal.

The present invention will be explained below with reference to embodiments shown in the drawings.

In FIG. 1, reference numeral 1 denotes a four-cylinder spark ignition internal combustion engine, which takes in an air/fuel mixture formed in a carburetor 2 through an intake pipe 3, and discharges exhaust gas after combustion through an exhaust pipe 4.

Rotors 5 and 6 rotate in synchronization with the crankshaft of the engine 1. The rotor 5 has one tooth 5a, and the rotor 6 has a large number of teeth 6a at each predetermined crank angle.

7 is a reference position sensor, and 8 is a speed sensor, both of which are composed of an electromagnetic pickup and the like. The sensor 7 generates one pulse signal every rotation of the crankshaft, and the sensor 8 generates a pulse signal every predetermined crankshaft (for example, every 5°C).

A microcomputer 10 calculates the ignition timing of the engine 1 based on signals from sensors 7 and 8 or a water temperature sensor, an oil temperature sensor, etc. (not shown). Reference numeral 9 denotes an ignition coil that generates high voltage based on a signal from the computer 10, and the high voltage is distributed to each spark plug via a distributor (not shown).

FIG. 2 is a block diagram showing the microcomputer 10. The microcomputer 10 includes a CPUll, ROM,
．． Memory 12 including RAM, I/O (input/output) circuit 13
, waveform-shapes the output signals of the sensors 7 and 8. Waveform shaping circuit 14, ignition drive circuit 1 for driving the ignition coil 9
5 and a common path 16. Since each block is well known, a detailed description of the hardware will be omitted.

In the above configuration, the computer 10 operates according to the flowchart shown in FIG. First, Stenop 20
Start from and initialize.

The average engine rotation speed N measured by the engine with one revolution of the crankshaft is read in the SteSob 2l, and the basic advance angle value θi is calculated from the rotation speed N using the map or formula in the memory 12 in the SteSob 22.

Next, the stepper 23 determines the rate of change dN/dt of the rotational speed N, and determines from this whether the engine 1 is in a steady state or a transient state. If the rate of change is within a certain value, it is determined to be in a steady state, and otherwise it is determined to be in a transient state.

If it is determined that the transient state is present, the basic advance value θi is set as the ignition timing θ in step 35, and the ignition drive circuit 1 is changed in step 36.
Output to 5.

When it is determined that it is in a steady state, it is averaged (
Set the variables SUM and M for statistical processing to zero. Next, in step 25, the program waits for the piston of the first cylinder among the four cylinders to reach top dead center (TDC). This is done based on the output signal of the sensor 7. In other words, tooth 5 of rotor 5
A is positioned to face the sensor 7 at the top dead center of the first cylinder, and when a pulse signal is output from the sensor 7, it is the top dead center of the first cylinder.

When the No. 1 cylinder reaches the top dead center, the step 26 reads the instantaneous engine rotational speed N1 at the top dead center. This is the rotational speed measured by the engine from the top dead center to a predetermined value after the top dead center (a value within the range of 5° to 10° ATDC) based on the signals from the sensors 7 and 8.

Next, wait for the No. 1 cylinder to reach 90°A after top dead center using the stem knob 27, and when it reaches ATDC 90°CA, read the instantaneous rotational speed N2 at ATDC 90°CA using the stem knob 28. This is a predetermined value (ATD
This is the rotational speed measured during the period up to (a value within the range of C95° to 100°).

Then, in step 29, the speed difference Δ between the rotational speeds N2 and N1 is
N is calculated using the following equation.

ΔN=N2−Nl The step controller 30 adds the current speed difference ΔN to the variable SUM, and counts the variable M by 1.

In step 31, it is determined whether the averaging (statistical) processing loop from steps 25 to 31 has been executed a specified number of times (MTH), and if the specified number of times (MTH) has not been reached, the process returns to step 25 and is processed again. Repeat. If the predetermined number of times has been reached, the average value ΔNave of ΔN, which is a statistical amount, is calculated in step 32.

ΔNave=SUM/MTH Then, in step 33, based on ΔNave indicating this load, data is read from the correction advance angle maso stored in the memory 12 and the load correction advance angle θ is determined.

Calculate. In step 34, the ignition timing θ is calculated using the following equation.

θ=θi+θC Next, the stesub 36 outputs this ignition timing θ. Then, the process returns to step 21 and performs the same loop process again.

Note that the ignition drive circuit 26 performs ignition at the previously calculated ignition timing until a new ignition timing θ is output from the computer 10.

Here, the speed difference ΔN and its average value ΔNave will be explained in detail. FIG. 4 shows a stroke diagram of a typical 4-cycle, 4-cylinder engine and the engine rotational speed during its operation. Looking at this process chart, top dead center (TDC)
When ignition is performed near TDC, the rotational speed of the internal combustion engine increases due to expansion energy due to combustion, and then the expansion energy is used up, and the rotational speed of the internal combustion engine reaches a peak value near ATDC90℃, and then the next The rotational speed of the internal combustion engine decreases due to the slight compression input (TDC
It can be seen that there is a characteristic of the internal combustion engine that the maximum value is the lowest. The m5 diagram shows this characteristic in more detail. FIG. 5 shows that the change in engine rotational speed varies depending on the engine load. That is, when the load is high, the amount of intake air increases, so the range of rotational fluctuations during compression and explosion increases. On the other hand, when the load is light, the amount of intake air is reduced, so rotational fluctuations are also reduced.

Therefore, it can be seen that the speed difference ΔN (=N2N+) roughly corresponds to the engine load. However, this speed difference ΔN
However, with this invention, the speed difference ΔN
is averaged (statistically) processed and ΔNave is calculated as a signal indicating the engine load, resulting in fewer false detections.

This is shown in Figure 6, which shows the average value ΔNav
It can be seen that e changes almost linearly with the engine load.

In the above embodiment, after calculating the average value ΔN3've, the corrected advance angle amount θC@ was calculated from the memory map using the average value ΔN3've as a Go, but as shown in FIG. The load correction advance angle may be determined for three types of light loads and the ignition timing may be controlled.

FIG. 8 shows a flowchart of the main part of the above control (second embodiment). The stems 20-32 in block A are similar to the stems in block A shown in FIG. After calculating the average value ΔNave in step 32, the average value ΔNave is compared with the high load judgment value NT+ in step 41. If ΔNave is larger than N'F+, it is determined that the load is high and the ignition timing θ is changed. The basic advance angle θi is set, and the advance is advanced to the steno knob 36 and output. On the other hand, if ΔNave is smaller than NT+, the process advances to step 42 and the light load judgment value NT
Compare with 2. If ΔNave is larger than NT2, it is determined that the load is medium, and the process proceeds to step 43, where the ignition timing θ is set to θ-θi+θC, and the process proceeds to step 36.

On the other hand, if ΔNave is smaller than NT2, it is determined that the load is light, and the process proceeds to step 44, where the ignition timing θ is set to θ - θi.
Set to +θc2. With the above control, the same effects as in the first embodiment can be obtained.

Further, in the second practical example, the load is divided into three stages: high load, medium load, and light load, but load detection can also be performed simply by detecting two stages of high load and light load.

FIG. 9 shows a third embodiment of the invention. That is, even in the fuel injection type engine control system, the same control as the conventional one is possible without using a special load detection sensor. In FIG. 9, 2A is an electromagnetic injector for fuel injection, and the other components are almost the same as those in the first embodiment.

The operation will be explained based on FIG. The stethoscope 51 reads information on the engine rotation speed N, the transmission position of the vehicle, the cooling water temperature, and the lubricating oil temperature, and based on this information, the next stethoscope 52 calculates the basic advance angle θi,
Calculate the basic injection amount Ti. From step 23 to step 32, calculations similar to those in block A of the first embodiment are performed.

In contrast to the average value ΔNave determined by the stethoscope 32, the average value ΔNave determined by the stethoscope 53 changes depending on the transmission position, water temperature, oil temperature, etc. even under the same load. Correct speed difference Δ by multiplying by
By using NH, the influence from disturbances other than engine load is minimized and load detection accuracy is improved.

In the stethop 54, the corrected average value ΔNH is changed to a certain set value N due to abnormal combustion (pre-ignition, misfire, etc.)
, F, and if it is larger than NF, it is determined that there is an abnormality, and the process moves to Step 7, where the ignition timing θ and the fuel injection amount T are set to fixed values θF and TF.
Output with SteSob59.

On the other hand, if it is determined that the corrected average value ΔNH is smaller than NF and there is no abnormality, the process moves to the step knob 56, calculates the load correction advance angle θC and the load correction injection amount Tc based on ΔNH, and the step step 58 calculates θC1θt. , Tc, and Ti, the ignition timing θ and fuel injection iT are calculated and outputted by the steno panel 59.

FIG. 11 does not show the fourth embodiment of the invention. In other words, in an engine control device that has a conventional load detection means (for example, a pressure sensor, an intake air amount sensor), control is normally performed using a load detection means such as a pressure sensor, but in the case of an abnormality such as a failure of the sensor. In addition, this invention can be used to control the engine, so that even if the pressure sensor fails, the output will deteriorate.
Prevent deterioration of fuel efficiency.

The operation will be explained based on flowchart 1 in FIG. First, the stethoscope 61 determines whether or not the load detection means, such as a pressure sensor, is normal or not based on the presence or absence of an abnormality in the output value of the pressure sensor. If the pressure sensor is determined to be normal, the process advances to the stethoscope 62 and the engine Rotational speed N Intake negative pressure (
(load) P, etc., a stethoscope 63 calculates the optimum ignition timing θ and fuel injection amount T according to the engine condition, and a next stethoscope 65 outputs the control values.

On the other hand, if the pressure sensor 61 determines that the pressure sensor is abnormal, the flow advances to the step 51 in the block B, performs the same processes 51 to 58 as shown in FIG. 10, and outputs the calculation results to the step 65.

In addition, in the above embodiment, the average value ΔNa of the rotational fluctuation amount ΔN
Although the load determination was performed using ve, the same effect can be obtained even if the load determination is performed using the standard deviation of the rotational fluctuation amount ΔN. It is also possible to process the same loop separately for each cylinder and control the ignition timing for each cylinder.

In performing the same control as in the first embodiment, in a cylinder having a cylinder discrimination sensor, the rotational fluctuation amount ΔN is determined for each cylinder.
By detecting i, filter judgment and load discrimination for each air, ignition timing control, fuel injection control, and filter processing control for each cylinder, it is possible to achieve optimal control for each cylinder during normal conditions and during abnormal conditions. It is also possible to perform optimal control for each cylinder.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a first embodiment of the invention, FIG. 2 is a block diagram showing the microcomputer shown in FIG. 1,
Figure 3 is a flowchart for explaining the operation, and Figure 4. Figures 5 and 6 are stroke diagrams, waveform diagrams, and characteristic diagrams for explaining the operation, respectively, and Figures 7 and 8 are the second diagrams of this invention, respectively.
Characteristic diagram showing an example. Flow chart, Figures 9 and 10
The figure is a schematic diagram and flowchart showing a third embodiment of the present invention.
1. FIG. 11 is a flowchart of the fourth embodiment of the present invention, and FIG. 12 is a block diagram of the present invention. 7... Reference position sensor, 8... Speed sensor, 10.
··Computer. -287- -288- -289-

Claims (1)

[Claims] (11) A speed sensor for detecting the rotation speed of the internal combustion engine, and a signal from the speed sensor at at least two predetermined crank positions, speed difference calculation means for calculating the difference; statistical calculation means for statistically calculating the rotational speed difference to calculate a statistic corresponding to the load of the engine; and ignition timing or fuel injection of the engine according to the statistic. (2) The statistical calculation means adjusts the rotational speed difference by a predetermined number of times, and The device according to claim 1, wherein the device is configured to calculate the average value of the addition results as the statistic. (3) The speed difference calculating means calculates the rotational speed for each The apparatus according to claim 1, wherein the statistical calculation means is configured to calculate the statistical amount on a case-by-case basis. (4) The speed difference calculation means is configured to operate when the load sensor is abnormal. An apparatus according to claim 1.