JPH0643833B2 - Signal measurement method for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION [Overview] The number of cylinders is automatically determined from the number of crank angle signals (NE signals) between ignition signals (IGT signals), and the top dead center signal (T
The top dead center timing of each cylinder is measured based on the DC signal).

[Industrial application field]

The present invention relates to a signal measuring method for measuring the top dead center of an internal combustion engine.

[Conventional technology]

Top dead center (TDC) of a multi-cylinder engine
r) can be detected based on the TDC signal generated once at 360 ° C (crank angle) and the NE signal generated at every 30 ° A. The ignition timing of each cylinder is generally set to be earlier than the top dead center, and its advance setting is an important control target for ignition control.

[Problems to be solved by the invention]

However, since the number of cylinders differs depending on the engine, it is not possible to directly apply the advance control of a certain model to an engine having a different number of cylinders.

The present invention provides a signal measuring method that can be directly applied to ignition control of an internal combustion engine having a different number of cylinders by automatically determining the number of cylinders.

[Means for solving problems]

The present invention is a first counter (CCRA) for determining the top dead center timing which is cleared every time the top dead center signal (TDC) is generated.
And a second counter (CLY) for discriminating the number of cylinders that is cleared each time an ignition signal (IGT) is generated. Both counters count the crank angle signal (NE) and the first counter ( The feature is that the timing at which the value of (CCRA) becomes a value (CTDC) that is an integer multiple of the value (CLYN) of the second counter (CLY) immediately before clearing is determined to be the top dead center.

[Action]

The counter (CLY) that is cleared each time the ignition signal (IGT) is generated has a count value (CLYN) immediately before clearing that corresponds to the number of cylinders. Moreover, the top dead center of each cylinder is cleared every time the top dead center signal (TDC) is generated.
It is the timing when the value of (CRA) becomes an integral multiple of CLYN. Therefore, the top dead center timing can be accurately detected even if the number of cylinders is not determined in advance.

〔Example〕

FIG. 1 is a system configuration diagram of the present invention.
Is its control device, 3 is a spark plug, 4 is a distributor, 5 is an igniter, 6 is an injector, 7 is a throttle, 8 is a vacuum sensor, 9 is a throttle position sensor, 10 is a water temperature sensor, 11 is an O ₂ sensor, 20
Is an ignition advance indicator.

The ignition advance display device 20 takes in three signals of IGT, G (TDC) and NE required for ignition control through an input / output circuit 21, processes them by the central processing unit 22 and displays the result (ignition advance). 23. FIG. 2 is a waveform diagram of the above three signals. The solid line TDC signal is for one cylinder and one of the other cylinder TDCs is at the dashed virtual position. The NE signal is generated every 30 ° C. A, for example, and the ignition advance can be obtained from the ratio of the time T _{2 of} one cycle and the time T ₁ between the NE and IGT signals.

However, the position of the virtual TDC cannot be determined from the TDC signal unless the number of cylinders is known.

FIG. 3 is an explanatory diagram of this cylinder number determination method. The number of cylinders can be determined based on the TDC signal generated once per engine revolution and how many times the IGT signal is generated during that period. From another point of view, it can be determined how many NE signals are generated between the IGT signals. In other words, NE between IGT signals
If the number of pulses CLYN is 6, it is 4 cylinders, if it is 4, it is 6 cylinders,
If it is 3, it means 8 cylinders.

CLY is the count value of the NE signal and is cleared for each IGT. Therefore, the value immediately before being cleared becomes CLYN corresponding to the number of cylinders. On the other hand, CCRA, which is also the count value of the NE signal, is cleared every TDC. This CCRA
Is an integer multiple of CLYN CTDCC = TDC + CLYN when TDC
It's timing. CTDC is 4 cylinders 0-6, 6 cylinders 0
-12 or 0-24, with a value of 0-24 for 8 cylinders.

The CPU 22 in FIG. 1 processes with two types of edge interrupts shown in FIG. CCRA and CLY by NE interrupt of (b)
Are counted up in step 21). And
In step S22, CCRA is compared with CTDC. If CCRA ≧ CTDC, the process branches to step S23, and when a TDC signal is detected, both CCRA and CTDC are cleared in step S24. If CCRA = CTDC is determined in step S25, it means that the TDC timing is detected. Therefore, in step S26, CTDC is set to CCRA.
Change to + CLYN (= CTDC + CLYN) and move to ignition control in step S27.

The IGT interrupt of (a) is a countermeasure against noise. That is, in step S11, the current CLY and the previous CLY, that is, CLY
0 is compared, and if they match, the match counter CCLY is incremented in step S12. Then, when CCLY exceeds a fixed value, for example, 4, CLY at that time is set to CLYN (steps S13 and S14). On the other hand, step S
If it is N (no) at 11, CCLY is cleared at step S15, and CLY0 is changed to CLY. In any case, CLY is cleared when passing through step S16.

〔The invention's effect〕

As described above, according to the present invention, since the top dead center can be obtained regardless of the number of cylinders of the engine, there is an advantage that ignition control of various engines can be performed by the same system.

[Brief description of drawings]

 FIG. 1 is a system configuration diagram of the present invention, FIG. 2 is an explanatory diagram of an ignition advance angle, FIG. 3 is an explanatory diagram of a cylinder number determination method, and FIG. 4 is a flowchart showing a process of the present invention.

Claims (1)

[Claims] 1. A first counter (CCR) for top dead center timing determination which is cleared every time a top dead center signal (TDC) is generated.
A) and a second counter (CLY) for determining the number of cylinders that is cleared every time the ignition signal (IGT) is generated. Both counters count the crank angle signal (NE),
An internal combustion engine characterized in that the timing at which the value of the first counter (CCRA) becomes a value (CTDC) that is an integer multiple of the value (CLYN) of the second counter (CLY) immediately before clearing is determined as top dead center. Signal measurement method.