JPH0320595B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for an internal combustion engine, and particularly to an ignition timing control device that detects combustion pressure (in-cylinder pressure) for each cylinder of an engine and controls ignition timing for each cylinder based on the combustion pressure. This invention relates to a timing control device.

In recent years, with the development of electronic components, various electronic components are being installed in automobiles, and so-called car electronics are being implemented.

Control of the internal combustion engine, that is, the engine and its peripheral devices, has also been computerized, allowing more precise control. One of these control devices is an ignition timing control device.

Ignition timing control is considered one of the most important controls in order to make the engine more efficient and to suppress harmful components in exhaust gas. That is,
Ignition timing is deeply involved in engine output torque, engine knock occurrence, combustion temperature, etc. If the ignition timing is incorrect, not only will the output torque be low, but it may also cause engine knock or abnormally high combustion temperature. Unfavorable effects such as increased NOx generation in the exhaust gas appear.

This ignition timing control is performed based on factors that indicate the engine operating condition, such as engine load, engine speed, intake pipe negative pressure, intake air amount, output torque, combustion pressure, etc. In order to maintain the output state of the engine most efficiently, MBT (Minimum
Advance for Best Torque) feedback control.

This is a method in which the torque of the output shaft of the engine is measured, the minimum ignition advance angle that maximizes the torque is determined by feedback control, and ignition is performed based on this ignition advance angle. However, since MBT feedback control measures the output torque of the crankshaft, which is the sum of the output of each cylinder of the engine, it is difficult to control the ignition timing of each cylinder to further improve engine efficiency. There was a problem that I couldn't do it.

In order to solve this problem, a device has been proposed that detects the combustion pressure in the cylinder, which is the source of output torque, and controls the ignition timing to increase this combustion pressure.

When detecting this combustion pressure, rather than simply detecting the maximum combustion pressure that produces instantaneous output, the combustion pressure that occurs during one cycle of one cylinder (cylinder) that generates output torque, as shown in the Shiatsu diagram in Figure 1, is detected. The indicated average of the effective pressure that presses the upper end surface of the piston (negative pressure in the case of suction stroke), that is, the area surrounded by the finger pressure line S ₁ (acts as output) and S ₂ (acts as pump work) The quotient of the difference divided by the stroke area Vh,
In other words, since more accurate control can be performed based on the indicated mean effective pressure Pi expressed as Pi = (S ₁ - S ₂ )/Vh, the ignition timing is controlled based on the indicated mean effective pressure Pi. ing.

However, in the case of a four-stroke engine, the indicated mean effective pressure Pi is expressed by the following formula: Pi=I/Vh720° 〓 θ=0°PθΔVθ...(1) (Vh: Stroke volume, θ: TDC (TDC) Crankshaft rotation angle from dead center), Pθ: combustion pressure at each rotation angle,
ΔVθ: Volume change at each rotation angle) When calculating using equation (1) to find Pi, a fairly high-speed multiplication function is required, which increases the cost of the ignition timing control device including the calculator. There were problems such as a lack of accuracy in control during transient states where the speed changes or during high-speed rotation.

An object of the present invention is to provide an ignition timing control device that solves the above-mentioned problems.

This purpose is to provide an ignition timing control device that outputs an ignition signal to each cylinder of the engine in synchronization with the rotation of the crankshaft according to the operating state of the engine, and a combustion pressure sensor that detects the combustion pressure of each cylinder is provided. An equal volume sensor is provided which emits a signal every time the cylinder volume changes by a certain amount in synchronization with the rotation of the crankshaft, and the combustion pressure detected by the combustion pressure sensor is sampled according to the signal from the equal volume sensor. The ignition timing control is characterized by being provided with a control circuit that calculates the indicated average effective pressure of the combustion pressure and outputs an output to the ignition timing control device so that the indicated average effective pressure for each cylinder is the highest based on the calculation result. This is accomplished by a device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings by giving an example.

FIG. 2 is a system diagram showing an outline of the engine and ignition timing control device. In the figure, 1 is an engine, 2 is a crankshaft, 3 is a slit plate fixed to the crankshaft 2, and 4 is a rotation angle signal for each fixed angle by the rotation of the slit plate 3, for a certain cylinder (for example, the first cylinder ) is a photo sensor that outputs a TDC signal representing the top dead center and a signal every time the cylinder volume changes by a certain amount (special volume change), and the rotation angle sensor 4
A, TDC sensor 4B and equal volume sensor 4C, 4
D (for example, 4C is for the 1st, 4th cylinder, 4D is for the 2nd,
(represents a 3-cylinder engine).

5 is an igniter 6, a distributor that distributes the high-pressure ignition signal outputted via the ignition coil 7 to the spark plugs of each cylinder; 8 is a combustion pressure sensor integrated into the spark plug attached to each cylinder; 9 indicates a control circuit. The control circuit 9 includes a microcomputer 10 and each sensor 4 including the photo sensor 4, as shown in FIG.
The combustion pressure P of each cylinder is sampled based on the equal volume signals of equal volume sensors 4C and 4D outputted via an amplifier 11 which amplifies the signals outputted from A, 4B, 4C, and 4D and shapes the waveform. It is composed of a computing unit 12 that computes the indicated mean effective pressure Pi for each cylinder. and microcomputer 10
has two input ports 13, 14 and output port 1
5. CPU 16 that performs calculation control of input/output data;
Temporarily stores input/output data, calculation results, etc.
RAM17, ROM where control programs are stored
18. It is composed of a clock generator (not shown) and the like.

As shown in FIG. 4, slits 3A, 3B, 3C, and 3D are formed in the slit plate 3 for each sensor 4A, 4B, 4C, and 4D, respectively. sensor 4
When the light emitted from the light emitting elements A, 4B, 4C and 4D is received through the slit plate, each sensor 4
The slit intervals and slit axes are appropriately determined so that predetermined signals are output from each of A, 4B, 4C, and 4D. In addition, since the slit plate 3 is provided directly on the crankshaft 2, the rotation of the crankshaft 2 is eliminated, and there is no possibility of gear backlash, etc., compared to, for example, a case where each sensor is provided inside the distributor 5, where rotation is transmitted through gears. It has the advantage of providing accurate signals that are completely synchronized with the

Next, the operation of this embodiment with the above configuration will be explained.

First, when the engine 1 is started, the control circuit 9 is also started, and a combustion pressure signal is sent to the computing unit 12 from the combustion pressure sensor 8 of each cylinder. In the arithmetic unit 12, the equal volume sensors 4C and 4D are connected via the amplifier 11.
Combustion pressure is accumulated every cycle by using the equal volume signal sent from (D: cylinder diameter, r: crank radius, λ:
Conrod, crank radius ratio) It is output every time the volume changes as expressed by the above equation (2) (for example, the stroke volume for one cycle of 720° is divided into 100).

As a result, the indicated mean effective pressure Pi shown in equation (1) above is
As is clear from the acupressure diagram in Figure 1, Pi=ΔV/Vh{180° 〓 θ=0°Pθ −360° 〓 θ=180°Pθ+540° 〓 θ=360°Pθ−720° 〓 θ= 540°Pθ} ...(3) As shown in equation (3) above, it can be calculated by adjusting and subtracting each of the four processes in one cylinder cycle, that is, the explosion process, exhaust process, intake process, and compression process. Therefore, the time required to calculate the indicated mean effective pressure Pi can be much reduced compared to the case where calculation is mainly performed by multiplication based on equation (1).

The indicated mean effective pressure Pi calculated by the calculator 12 in this way is converted into a digital signal by the A/D converter in the calculator 12 and then sent to the microcomputer 10.
is sent to the input port 14 of the CPU 16 and taken into the CPU 16. In the microcomputer 10, the ROM as shown in the flowchart of FIG.
Arithmetic processing is performed according to a control program stored in 18.

That is, in step 20, the indicated mean effective pressure Pi calculated by the calculator 12 via the input port 14 is
is read, and the process moves to the next step 21.

In step 21, the indicated mean effective pressure Pi' calculated in the previous cycle and stored in a predetermined area in the RAM 17, and the indicated mean effective pressure Pi' calculated in the previous cycle and stored in the RAM 17 in the same way are calculated. The calculated indicated mean effective pressure Pi is compared and judged, and if Pi > Pi′, the judgment result is “YES”.
Then, the process moves to step 22. On the other hand, if Pi≦Pi', the determination result is "NO" and the process moves to step 23.

In step 22, the current indicated mean effective pressure Pi
is higher than the previous indicated mean effective pressure Pi', processing is performed to further advance the ignition timing θi at the time of the previous ignition by an angle indicated by α, for example, 0.5°.

On the other hand, in step 23, contrary to the case of step 22, since the current indicated mean effective pressure Pi is less than the previous indicated mean effective pressure Pi', the basic ignition timing θi is changed to the angle indicated by α', for example 0.6°. Processing is performed such as retarding the angle by a certain amount. Note that the retard angle amount α' may be the same size as the advance angle amount α.

After determining the ignition timing θi in this manner, the processing of this control program ends.

Then, in the next cycle, the ignition signal corresponding to the above-mentioned ignition timing θi is transmitted to the rotation angle sensor 4A and
Based on the basic ignition timing θb determined from the signal from the TDC sensor 4B, it is output from the output port 15 to the primary side of the ignition coil 7 via the igniter 6 at a timing advanced or retarded from θb, and further to the ignition coil 7. The high voltage current generated on the secondary side of the cylinder 7 is supplied via the distributor 5 to the spark plug of the cylinder at the ignition timing.

As described above, the ignition timing θi for each cylinder is calculated at high speed, and the ignition plug is ignited based on this, so that the indicated mean effective pressure Pi is the highest at each load, as shown by the solid line in Figure 6. Control is performed by ignition timing that approximately corresponds to the high points (points X, Y, and Z). As a result, as shown by the broken line in the figure, the engine is controlled with fuel efficiency that approximately corresponds to the lowest point (point a, point b, point c) on the fuel efficiency curve at each load.

As detailed above, the ignition timing control device of the present invention generates a signal for every equal volume change of the cylinder based on the combustion pressure detected by the combustion pressure sensor attached to each cylinder of the engine (internal combustion engine). It has a control circuit that performs sampling in accordance with the signal of the equal volume sensor, calculates the indicated mean effective pressure Pi from the sampled value, and calculates and controls the ignition timing so that the indicated mean effective pressure Pi becomes the highest.

Therefore, according to the present invention, it is possible to calculate the indicated mean effective pressure Pi by only adding and subtracting, and there is no need to use a high-speed calculator unlike in the past, and it is also possible to calculate the indicated mean effective pressure Pi by adding and subtracting. This has the effect of improving followability and accuracy, which in turn improves fuel efficiency and improves drivability.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the correlation between the combustion pressure in each cylinder and the cylinder volume of the cylinder, Fig. 2 is a schematic system diagram showing an engine and ignition timing control device according to an embodiment of the present invention, and Fig. 3 is a control circuit as well. A block diagram showing
Figure 4 is a plan view showing the slit plate, and Figure 5 is a plan view showing the slit plate.
The figure is a flowchart showing the ignition timing control program of this embodiment, and FIG. 6 is an explanatory diagram showing the effects of this embodiment. DESCRIPTION OF SYMBOLS 1... Engine, 2... Crankshaft, 3... Slit plate, 4... Photo sensor, 8... Combustion pressure sensor, 9... Control circuit, 10... Microcomputer, 12... Arithmetic unit, 16... CPU.

Claims (1)

[Claims] 1. In an ignition timing control device that outputs an ignition signal to each cylinder of the engine in synchronization with the rotation of the crankshaft according to the operating state of the engine, a combustion pressure sensor is provided to detect combustion pressure for each cylinder, and An equal volume sensor is provided that emits a signal every time the cylinder volume changes by a certain amount in synchronization with the rotation, and the combustion pressure detected by the combustion pressure sensor is sampled according to the signal from the equal volume sensor to determine the combustion pressure. An ignition timing control device comprising: a control circuit that calculates an indicated average effective pressure of the engine and outputs an ignition timing control signal so that the indicated average effective pressure of each cylinder is maximized based on the calculation result.