JPH03121238A - Cylinder discriminating method for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent wrong detection in a device for comparing the generated pulse separation between first position signals and second position signals, generated among the first position signals, for discriminating a specific cylinder so as to discriminate the operating position of each cylinder by forbidding discriminating action for the specified period after engine start-up. CONSTITUTION:A rotary disc 2 on an axis of rotation 1 rotated synchronously with an internal combustion engine is provided with plural slit-like windows 3a, 3b' in the positions corresponding to the reference positions of each cylinder and a specific cylinder. In each window 3a among these windows 3a, 3b', one end on the front side in the rotating direction corresponds to the first reference position of each cylinder, and the other end corresponds to the second reference position, as well as the window 3b' is disposed on the same circumference as the window 3a, next to the window 3a of the specific cylinder. On the basis of the comparison of the generated pulse separation of the first and second position signals, the operating position of each cylinder is discriminated, but in this case, the cylinder discriminating action is forbidden for the specified period after the start up of an engine.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a cylinder identification method for an internal combustion engine that identifies the operating position of each cylinder based on a single system of position signals, and in particular, relates to a cylinder identification method for an internal combustion engine that realizes cost reduction and cylinder identification. The present invention relates to a cylinder identification device for an internal combustion engine that prevents false detection.

[Prior Art] Conventionally, internal combustion engines such as automobiles are driven to rotate at several 1100 rpm to several 1100 rpm using a plurality of cylinders (for example, four cylinders). In the case of a 4-cylinder, each cylinder is connected to the drive shaft (crankshaft) with a phase difference of 1/2 period, but for two rotations of the crankshaft, intake, compression, explosion, Since exhaust is performed, the operating position of the camshaft that controls the drive cycle of each cylinder is out of phase by 1/4 cycle.

In such an internal combustion engine, in order to electronically control the ignition timing by the igniter, the fuel injection timing by the injector, etc. for each cylinder, a position signal is generated for each cylinder in synchronization with the rotation of the internal combustion engine. It is necessary to identify the operating position of each cylinder based on this position signal. Usually, a rotation signal generator that detects rotation of a camshaft or crankshaft of an internal combustion engine is used as a means for generating a position signal corresponding to a reference position of each cylinder.

Figure 2 is a block diagram showing a general cylinder identification device for internal combustion engines. In the figure, (8) is a rotation signal generator that generates a position signal corresponding to each cylinder, and The interface circuit (10) for importing is a microcomputer that processes the position signal input via the interface circuit (9) to identify the operating position of the cylinder.

FIG. 3 is a perspective view showing a specific configuration example of the rotation signal generator (8) in FIG. 2, and FIG. 4 is a perspective view of the rotation signal generator (8) in FIG.
FIG.

In Fig. 3, (1) is a rotating shaft that rotates in synchronization with the internal combustion engine.
It is connected to a camshaft that rotates once in synchronization with the cycle.

(2) is a rotating disk attached to the rotating shaft (1), and there are a plurality of rotary discs at positions corresponding to the reference position (predetermined rotation angle) for each cylinder, as well as at positions corresponding to the reference position of a specific cylinder. Slit-shaped windows (3&) and (3b) are provided. Here, the case where the internal combustion engine is a four-cylinder engine is shown, and regarding the windows (3a) provided at four locations along the outer periphery, one end on the front side with respect to the rotation direction (arrow) is the first end of each cylinder.
corresponds to the reference position, and one end on the rear side corresponds to the second reference position.

Further, the window (3b) provided at one location on the inner circumference is arranged to correspond to the window (3a) of only one specific cylinder (first cylinder), and has a phase difference with respect to the window (3a). have.

(4a) and (4b) are a pair of light emitting diodes arranged to face the good intentions (3a) and (3b), respectively, and (5a) and (5b) are light emitting diodes from each light emitting diode (4a) and (4b). A pair of photodiodes arranged to receive output light through windows (3a) and (3b).

These light emitting diodes (4a) and (4b) and photodiodes (5a) and (5b) constitute two sets of photocouplers.

In FIG. 4, light emitting diodes (4a) and (4b)
The photodiodes (5a) and (5b) are typically shown as (4) and (5), and only one photocoupler is shown. (6) is an amplifier circuit that amplifies the output signal from the photodiode (5); (7)
is an oven collector (grounded emitter) output transistor whose base is connected to the output terminal of the amplifier circuit (6). The collector terminal of the output transistor (7>) is connected to an interface circuit (9) (see FIG. 2).

Next, the operation of the conventional internal combustion engine cylinder identification device shown in FIGS. 2 to 4 will be described with reference to the waveform diagram in FIG. 5.

When the rotating shaft (1) rotates and the rotating disk (2) rotates as the internal combustion engine rotates, the rotation signal generator (8) outputs the following:
Each photodiode (5a) and (5b) of two sets of photocouplers are arranged facing each other with windows (3a) and (3b) in between.
), two types of position signals are output, which rise at the front end and fall at the rear end of the slits forming the windows (3a) and (3b), and L2 (see FIG. 5).

In FIG. 5, the first position signal L1 obtained based on the window (3a) is a crank angle reference signal called SGT, and is inverted at a predetermined crank angle for each cylinder #1 to #4. Here, each crank angle reference signal rises at a crank angle of 0°, which is called B75° for each cylinder.
The trailing edge indicates a first reference position 75° before TDC (TDC = upper dead center), and the falling edge indicates a second reference position 5° before TDC, called B5''. The reference position B75° corresponds to the control reference angle,
The second reference position I B 5° corresponds to the initial ignition angle.

Further, the second position signal L2 obtained based on the window (3b) E
is a cylinder identification signal called SGC, and a specific #1
It is output when a cylinder signal is generated and is used to identify the #1 cylinder.

The operating position of each cylinder is shifted by 1/4 period with respect to one period of the camshaft (corresponding to two periods of the crankshaft, or 720 degrees), and is deviated by 1/2 period with respect to one period of the crankshaft. They are shifted by a period (180°). Further, as is well known, each cylinder operates in the order of #1 cylinder, #3 cylinder, #4 cylinder, and #2 cylinder.

On the other hand, the cylinder identification signal L2 is set to rise before the rise of the crank angle reference signal L2 corresponding to the specific #1 cylinder, and to fall after the fall of the position signal L2.

The two types of position signals obtained in this way and L2 are input to the microcomputer (10) via the interface circuit (9). and a second position signal,
In addition to identifying the specific #1 cylinder based on the first position signal L1, the operating position of each cylinder #2 to #4 is identified based on the first position signal L1, and the ignition timing and fuel injection (sequence and group injection) are determined.
Used for control calculations such as

However, in the cylinder identification device as described above, since two systems of position signals Ll and L2 are used, the configuration of the rotation signal generator (8) becomes complicated, and there is a problem that cost reduction cannot be achieved.

Therefore, a device can be considered that uses a rotation signal generator (8) as shown in FIG. 6 to transmit one system of position signals L1 and L2'. In this case, the light emitting diode (4) and the photodiode (5) constitute a set of photocouplers. Further, (3b') is a window for identifying a specific cylinder corresponding to the window (3b), and a window (3a) for detecting a reference crank angle.
is located on the same circumference as

The window (3b') for identifying the specific cylinder is placed next to the window (3a) that indicates the first and second reference positions of the specific cylinder. Two position signals L+ and L2' are obtained.

In FIG. 6, the other configurations are the same as in FIG. 3, and
The configuration of the entire device and the configuration of the position signal generator are as shown in FIGS. 2 and 4, respectively.

Next, a cylinder identification method using the rotation signal generator (8) of FIG. 6 will be described with reference to the waveform diagram of FIG. 7 and the flowchart of FIG. 8.

Similarly to the above, when the rotating disk (2) rotates in the direction of the arrow, the rotation signal generator (8) is From there, continuous first and second position signals L1 and L2' are generated as shown in FIG. here,
The fall of the second position signal L2' corresponds to, for example, a reference position 5 degrees after TDC called A5 degree for a particular cylinder.

Next, the microcomputer (10) (see Figure 2)
In order to identify each position signal L (L, and L2') sent from the rotation signal generator (8) via the interface circuit (9) as one system of signals as shown in FIG. Step S calculates the high level period (pulse width) and rise period (pulse interval) T of each position signal, and further, based on the values obtained in step S1,
The duty (t/T) of each pulse is calculated (step S2). Then, based on the calculation result in step S2, take the absolute value of the difference between the previous data (t/T)n-1 and the current data (t/T)n, and check whether this value is larger than a predetermined value α. is determined (step S3).

If 1 in Figure 7. When the duty (t/T) changes greatly, such as from T1 to t2 and T2, it is determined that the absolute value of the ratio data difference is larger than the predetermined value α,
The specific #1 cylinder is identified.

Therefore, after the flag representing the specific cylinder (#1 cylinder) is set in the register in the microcomputer (10) (step S4), the process returns to end the cylinder identification operation (step S5).

On the other hand, if it is determined in step S3 that the absolute value of the duty difference is less than or equal to the predetermined value α, the process returns immediately (step S5), and # is determined based on the first position signal with reference to the specific cylinder. Cylinder 3, cylinder #4, and cylinder #2 are sequentially identified.

In this way, by recognizing the position signal L1 corresponding to each cylinder, it is possible to cut off current to the ignition coil of each cylinder at a predetermined optimum timing, for example. At this time, the second position signal L2' for identifying the specific cylinder is
occurs after the fall of the position signal L1, and is set after the initial ignition position f (B5°), so when cranking the internal combustion engine (when starting the crank by motor drive), the position shown in FIG. Even if the signal L is used as it is to cut off the ignition coil's current (ignition at the falling edge) and the ignition coil's current is cut off using the second position signal L2' for identifying a specific cylinder, the first position signal Since this is after the normal initial ignition by L1, there will be no starting failure of the internal combustion engine. Although the pulse duty (t/T) of each position signal was calculated in step S2 above, the low level period (T-
The ratio of high level period t to t) [t/(T-t)
] may be calculated. In this case, the period difference due to the pulse interval variation becomes large, and the detection sensitivity of a specific cylinder is further improved.

However, one system of position signals L1 and L2 as described above
In the cylinder identification method using
The generation cycle of the first position signal (crank angle reference signal 5GT) L varies greatly, and abnormal cylinder identification results due to erroneous detection are reflected in control.

[Problems to be Solved by the Invention] As described above, the conventional internal combustion engine cylinder identification method uses two types of position signals, and L2, that is, the crank angle reference signal SGT.
When using the cylinder identification signal SGC, it is necessary to generate two systems of signals using two sets of photocouplers, resulting in a complicated configuration and an increase in cost.

In addition, in the internal combustion engine cylinder identification method using one system of position signals L2' and L2', if the generation cycle of the first position signal L1 fluctuates at the initial stage of startup, abnormal cylinder identification results due to erroneous detection may occur. There was a problem that it was reflected in the image and caused problems.

This invention was made to solve the above-mentioned problems, and provides a cylinder identification method for an internal combustion engine that uses a single system of position signals to reduce costs and prevent false detection of cylinder identification. The purpose is to

[Means for Solving the Problems] A cylinder identification method for an internal combustion engine according to the present invention generates a second position signal for identifying a specific cylinder between first position signals, and adjusts the generation pulse interval of each position signal. The operating position of each cylinder is identified based on the comparison of , and the cylinder identification operation is not performed for a predetermined period after starting the internal combustion engine.

[Operation] In the present invention, it is determined whether or not it is in the early stage of startup, and if it is not in the early stage of startup, the operating position of a specific cylinder is identified based on the pulse interval of each position signal of one system, and if it is in the early stage of startup, the operating position of the specific cylinder is identified. Skip the identification operation.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a flowchart showing one embodiment of the present invention, and steps 31 to S5 are the same steps as described above. The apparatus to which this invention is applied is as shown in FIGS. 2, 4, and 6, and one system of position signals generated is
It is similar to the figure. Therefore, as described above, the rising edge (B75°) of the first position signal T-1 shown in FIG. 7 is used as the control reference angle, and the falling edge (B5°) is used as the initial ignition angle.

In FIG. 1, first, it is determined whether or not the internal combustion engine is in the initial stage of startup (step SO), and if it is not in the early stage of startup, the above-mentioned steps S1 to S4 (not explained here) are executed, If it is the initial stage of startup, the process immediately proceeds to step S5 and returns. This prevents abnormal cylinder identification results due to erroneous detection from being used for control.

The criterion in step SO can be set, for example, by detecting a starter key switch signal and determining whether a predetermined period of time has elapsed since the start of the engine. If the predetermined time has not elapsed, it is determined that the engine is in the early stages of startup, and if the predetermined time has elapsed, it is determined that the engine is not in the early stages of startup.

Further, as another determination method, for example, a method based on the number of ignitions, the number of revolutions, or the switch-off signal of the starter key of the internal combustion engine can be considered, and it goes without saying that any of these methods will have the same effect.

[Effects of the Invention] As described above, according to the present invention, the second position signal for identifying a specific cylinder is generated between the first position signals, and each position signal is determined based on a comparison of the generated pulse intervals of each position signal. In addition to identifying the operating position of the cylinder, the cylinder identification operation is not performed during a predetermined period after starting when the rotation period has large fluctuations.
This has the effect of providing an internal combustion engine cylinder identification method that reduces costs and prevents erroneous detection.

[Brief explanation of drawings]

FIG. 1 is a flow chart diagram showing an embodiment of the present invention;
Fig. 2 is a block diagram showing a general cylinder identification device for internal combustion engines, Fig. 3 is a perspective view showing the rotation signal generator in Fig. 2, and Fig. 4 is a position signal generating section in the rotation signal generator. FIG. 5 is a waveform diagram showing the position signals generated by the rotational signal generator of FIGS. 3 and 4, FIG. 6 is a perspective view of the improved rotational signal generator, and FIG. 6 is a waveform diagram showing a position signal generated by the rotation signal generator of FIG. 6, and FIG. 8 is a flowchart for explaining a method for identifying cylinders for an internal combustion engine using the rotation signal generator of FIG. 6. be. (8)...Rotation signal generator Ll...First position signal L2...Second position signal SO...Step S3 to determine the initial stage of startup...Step to determine the specific cylinder In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A second position signal for identifying a specific cylinder is generated between first position signals corresponding to each cylinder for rotational driving of the internal combustion engine, and based on a comparison of generation pulse intervals of the first and second position signals. 1. A cylinder identification method for an internal combustion engine in which the cylinder identification operation is not performed for a predetermined period after the start of the internal combustion engine.