JPH0633758B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ignition timing control device for an internal combustion engine.

Background Art A cylinder pressure change is obtained as a so-called finger pressure signal by forming a through hole communicating with a combustion chamber in a member forming a combustion chamber such as a cylinder head of an internal combustion engine and inserting a pressure sensor using a piezoelectric element or the like into the through hole. You can Further, a method of obtaining a finger pressure signal by interposing a pressure gauge at the connecting portion between the cylinder head and the cylinder block is also conceivable.

It can be seen that the change in the engine cylinder internal pressure in the operating state of the internal combustion engine is as shown by the curve A in FIG. If the ignition system is triggered at the ignition angle θ _IG , the ignition delay θ
The mixture gas is ignited with d, and the cylinder pressure rises sharply thereafter and reaches the maximum pressure peak P (hereinafter referred to as the acupressure peak).
Follow the process of descending via.

By the way, it is known that the crank angle position of the acupressure peak is related to the state where the engine exerts the maximum output, and the crank angle position of the acupressure peak that can give the maximum output is the top dead center as shown in the figure. Later (hereinafter ATD
It was experimentally confirmed that the temperature was in the range of 12 ° to 13 ° (referred to as C). Therefore, the ideal crank angle position of this ATDC is 12 ° to 13 °. Therefore, the acupressure peak is A
It is desirable to set the ignition timing θ _IG such that the ideal crank angle position of TDC 12 ° to 13 ° is obtained.

However, even if the ignition timing θ _IG is kept constant, the acupressure peak changes every moment depending on the engine operating state, and an ignition timing control device that holds the acupressure peak at the optimum position is desired.

Therefore, a feedback control system that obtains a finger pressure signal representing the cylinder pressure, detects the position of this peak value on the crank angle as finger pressure peak position data for each engine cycle, and advances or retards the ignition angle is constructed. Can be considered.

In this case, the peak position of the finger pressure fluctuates in each engine cycle, and if the ignition angle greatly differs in each engine cycle, it is not so preferable from the viewpoint of the operational stability of the engine.

In addition, it is also necessary to distinguish the control state from when the engine is in a transient state due to a sudden change in load or the like and change the control characteristic.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ignition timing control device that distinguishes a normal state and a transient state of an internal combustion engine to maintain operational stability and controls an ignition angle by a finger pressure peak position data signal. is there.

In the ignition timing control device according to the present invention, the acupressure peak position data obtained for each engine cycle is sequentially stored, and a plurality of stored peak position data are combined to obtain new peak position data, and When the engine is in a transient state, the ignition timing is controlled so as to reduce the number of data to be combined.

Embodiment FIG. 2 shows an ignition timing control device according to the present invention. In this device, a through hole is formed in a member such as a cylinder head forming a combustion chamber of an internal combustion engine (not shown), and a piezoelectric element is formed in the through hole. A finger pressure signal generation circuit 1 obtained by inserting a pressure sensor such as an element into close contact so that the detection head is exposed in the combustion chamber is included. The clock generation circuit 2 generates a clock pulse having a predetermined cycle or synchronized with engine rotation. As a means to obtain a clock pulse synchronized with the engine rotation, it is a disk that rotates in response to the rotation of the crankshaft.By combining a photocoupler with a slit disk having many slits at equal intervals, the output signal of the photocoupler is used. Means for obtaining clock pulses are known. The reference position generation circuit 3 receives a reference position signal indicating that the crank angle position, that is, the engine rotation angle position has reached the reference position, for example, TDC (Top Dea).
d Center) pulse is generated. This TDC pulse is applied to the slit disk used for the clock generation circuit 2 by the TDC.
It can be obtained by separately providing a pulse slit and a TDC pulse generating photocoupler. The peak hold circuit 4 holds the maximum value in the acupressure signal after being cleared by the reference position signal, and the comparison circuit 5 emits the acupressure signal when the acupressure signal confidence falls below the maximum value. The counter 6 for measuring the crank angle position counts clock pulses and is cleared by the reference position signal, and the count value of the counter 6 is, for example, 8-bit data and indicates the present value of the crank angle. The latch circuit 10 latches the count value of the counter 6 each time the peak detection signal from the comparison circuit 5 is supplied to its gate terminal g, while the decoder 11 causes the count value of the counter 6 to be 63, for example. When, the read command signal is supplied to the ignition angle setting circuit 8. The count value 63 corresponds to a crank angle that is larger than the crank angle at which the acupressure peak value is predicted to occur, and obtains a reading timing that is not affected even if the valve seating noise of the exhaust valve is mixed in the acupressure signal. ing. In response to this, the ignition angle setting circuit 8 reads the content of the latch circuit 10 and determines the content of this latch as the peak position information θpx on the crank angle. It is also conceivable that the latch contents are supplied to the ignition angle setting circuit 8 via a gate circuit that opens the gate in response to a read command signal from the decoder 11. The ignition angle setting circuit 8 is composed of a microprocessor or the like, and supplies desired ignition angle θ _IG data to the ignition command circuit 9 according to a program described later based on the supplied peak position information (data) θpx. The ignition command circuit 9 counts clock pulses with the reference position signal as a reference and calculates the crank angle present value θig.
The know, is ignited by the this current value θig and the input theta _IG forms the opening of the ignition switch SW if they match, an ignition plug (not shown) thereby ignition current flows through the primary coil of the ignition transformer T Done. The ignition switch SW
Various ignition circuits including an ignition transformer T and an ignition transformer T are known, and the illustrated circuit is merely an example. Also,
The ignition angle setting circuit 8 and the ignition command circuit 9 form ignition command means. The ignition angle setting circuit 8 may also have a mode of operating based on various engine parameters from the engine parameter sensor 12, that is, the engine speed Ne, the suction negative pressure P _B throttle opening θth, and the like.

FIGS. 3A to 3F are signal waveform diagrams for explaining the operation of the circuit of the above embodiment. That is, the reference position signal and the clock pulse are as shown in FIGS. 3 (A) and 3 (B), respectively. The acupressure signal changes as shown by the solid line in FIG. 3C, and therefore the output of the peak hold circuit 4 is as shown by the dotted line in FIG. 4C. The comparison circuit 5 issues a peak detection pulse signal as shown in FIG. 3D for each maximum point of the acupressure signal. FIG. 3 (E) shows the state of change of the count value of the counter by numbers.

FIG. 3 (F) shows the states of changes in the latch contents of the latch circuit 10 by numbers. FIG. 4 (G) shows a decoder 11
Of the read command signal. In this case, the high level is the read command signal.

FIG. 4 shows an example of a program relating to ignition control of the ignition angle setting circuit 8 of the device shown in FIG. That is, when performing the ignition control operation, the ignition angle setting circuit 8 first sets the ignition angle θ _IG to the initial value θ _IG0 , waits for a read command signal from the decoder 11, and receives the read command signal. And the latch contents of the latch circuit 10 are fetched as peak position information θ _PX (step S ₁ ,
S ₂ ). Next, this peak position information θpx is the top dead center angle θ.
_It is judged whether it is larger or smaller than the sum of _TDC and the angle α of 12 °, for example (step S ₃ ), and if larger, the ignition angle θ _IG
Is advanced by Δθ (step S ₄ ), and if it is smaller, the ignition angle θ _IG is retarded by Δθ (step S ₅ ). Step S ₁ from start to end
1 to S ₅ are sequentially executed in response to the clock pulse, and the cycle operation is repeated. The following programs are similar in this respect.

FIG. 5 shows an example of an operation program when the ignition command circuit 9 is formed by a microprocessor. That is, when the ignition command circuit 9 detects the reference device signal (step S _11), the crank angle current value θig of the internal register is set to theta _{TDC (or} a predetermined value) (step S
₁₂ ). Next, the ignition angle data θ from the ignition angle setting circuit 8
_{The IG} is taken in (step ₁₂ ), and this is compared with the crank angle present value θig. When the condition of θig = θ _IG is satisfied, an ignition command is immediately issued (steps S ₁₄ and S ₁₅ ), and the ignition switch SW is opened. On the other hand, in the case of? Ig ≠ theta _IG adding unit crank angle δθ to? Ig to prepare for the next program cycle (step S _16). In step S _14, instead of the? Ig = theta _IG determined whether, also conceivable that the difference between? Ig and theta _IG is small becomes determined whether from .delta..theta.

In the above example, the peak position data θ _PX is obtained for each engine cycle, and the ignition angle for the next cycle is determined by θ _PX in each cycle.

FIG. 6 shows an operation program example of the ignition angle setting circuit 8 in the ignition timing control device according to the present invention. In this program, when the read command signal from the decoder 11 is present, the acupressure peak data θ _PX is read (steps S ₁ and S _{2 a} ), and the advance angle or the advance angle is determined by knowing the magnitude of θ _PX and (θ _TDC + α). allowed to retard (step S ₃ a,
S ₄ a, S ₅ a) The basic flow is the same as the program shown in the flowchart of FIG.

However, in this example, θ _PX is grasped as a data group that occurs in time series, and the finger pressure peak position data obtained in the Nth engine cycle is represented as θ _PX (N) (step S2a).

By the way, in the case of engine misfire, combustion in the cylinder does not occur, and the acupressure peak position occurs near θ _TDC .
Further, since the finger pressure peak position data in the cycle in which the engine misfire occurs is not based on normal combustion, it is not appropriate to use it as the basis of the finger pressure peak position control in the next cycle. Therefore, first, θ _PX (N) is compared with θ _TDC, and only when the difference exceeds Δθ, the calculation of θ _PX (N) is performed (steps S ₂₀ , ₂₁ ). In this operation step S ₂₁ is By the following formula, the past engine cycle (N-1),
The (N−2), ... (N−n) data value of the finger pressure peak position in the engine cycle is corrected this time to increase the stability of the feedback system.

As a specific example of ω _{n in} the above formula, ω ₀ = ω ₁ = ω ₂ = ω
₃ = ω ₄ = 1/5, ω ₅ = ω ₆ = ... = ω _n = 0,
It is also possible to use the average value of the data of the past four times and the data of this time as the data of this time. The averaging method is not limited to this, and the data is averaged a suitable number of times. Also,
It may be considered that ω _n = (1 / L) ⁿ (L> 1, n> 0).

The advance angle and the retard angle are controlled by the magnitude of θ _PX (N) and (θ _TDC + α) thus obtained (steps S ₄ a, S ₅ a), but the advance amount Δθ ₁ and the retard amount Δθ ₂ is not necessarily the same value, and Δθ ₁ > Δθ ₂ or Δθ ₁ <Δθ ₂ can be set according to the characteristics of the feedback system. Further, Δθ ₁ and Δθ ₂ can be functions of the difference between θ _PX (N) and (θ _TDC + α).

On the other hand, the difference is a K ₁ unless the following situations Δθ is K ₁ <K ₁ m as K ₁ +1 (step S _22, S ₂₃₎ retard control of the theta _PX (N) and theta _TDC (Step S ₅ If a misfire occurs continuously and K ₁ ≧ K ₁ m is satisfied, initialization is performed to reset the ignition timing (step S ₂₄ ).
_{When PX-} θ _TDC |> Δθ, K _{1 is set} to 0 and the next step is entered (step S ₂₅ ). Note that, as indicated by a broken line l ₁ , it is possible to directly enter the next program cycle without performing the retard control at the time of engine misfire. It is also possible to ignore the exhaust stroke data when the ignition timing control device is used for a four-cycle engine. This eliminates the need for the exhaust stroke determination sensor.

FIG. 7 shows another operation program example of the ignition angle setting circuit 8. That is, in this program, the control target value θ _PX i of θ _PX (N) is (θ _TDC + α)
Instead of a single angle, the control target area is set as θ _PX i ± β (X) (step S ₃₀ ). By doing so, the stability of the feedback system as a whole is improved. Incidentally, X of beta (X) is engine rotational speed N _e, the throttle opening theta _TH, can be either the first engine intake negative pressure P _B. It is also conceivable to change the value of β using the combination of these engine parameters as a variable. The other points are the same as the program of FIG. Note that β (x) may be a constant β.

In the flow charts of FIGS. 6 and 7 described above, the peak position data θ _{PX is set} to the Nth sample value θ.
Instead of determining only by _PX (N), (N-
1), (N−2), ... (N−n) The configuration is such that the finger pressure peak position data value in the (N−n) th engine cycle is combined to obtain the Nth sample value, that is, the current sample value θ _PX (N). Is set to 4, for example, and a total of 5 sample values of the current sample value and the past 4 sample values are combined by averaging.

However, rather than always adopting the method of constant sample value synthesis regardless of the engine operating state, there are different modes in the case of the transient motion state of the engine such as a sudden change of load and the case of the normal operating state. It has been found preferable to synthesize sample values.

Further, as shown in the flow chart of FIG. 7, proper control is performed by changing the size of the control target range width ± β (x) between the transient state of the engine and the normal operating state. It has been found.

Therefore, it is conceivable to give the ignition angle setting circuit 8 the function shown by the subroutine program of FIG. According to this additional function, the ignition angle setting circuit 8 sets ΔNe (N) as the difference between the current value Ne (N) and the previous value Ne (N-1) of the engine speed data obtained from the engine parameter sensor 12. (Step S ₃₀ ), ΔNe (N)
Is compared with a predetermined threshold value ΔNer, and if it exceeds this, it is determined that the engine is in a transient state (step S ₃₁ ). On the other hand, △
When Ne (N) does not exceed ΔNer, the intake pipe negative pressure P _B
Of the sample data of the current value P _B (N) and the previous value P _B
The difference between the (N-1) and △ _P as B (N) (step _{S 32), △ P B (} N) is determined exceeds a predetermined threshold value △ _{P B} r and the transient state of the engine (step S ₃₃ ).
Also, △ P _{if B} (N) does not exceed the △ P _B r is the current value of the sample data of the throttle opening theta _TH theta
The difference between _TH (N) and the previous value θ _TH (N-1) is θ
_{As TH} (N) (step S ₃₄ ), when θ _TH (N) exceeds a predetermined threshold value Δθ _TH r, it is determined that the engine is in a transient state (step S ₃₅ ). On the other hand, θ _TH (N) is Δθ
_{If TH} r is not exceeded, it is determined that the engine is in a normal state, β (x) is set to β ₀ (x) (step S ₃₆ ), and the composite data number n of θ _PX (N) is m _0. Is set (step S ₃₇ ).

On the other hand, at the time of the above transient state determination, ββ (x)
Is set to β ₁ (x) (step S ₃₈ ), and the number n of combined data is set to m ₁ (step S ₃₉ ). Where β
₀ (x)> β ₁ (x)> m ₀ m ₁ .

In the above flow chart, Ne, P _B and θ
The order of each transient state determination step depending on _TH is not limited to the illustrated order, and the transient state determination may be performed in the order of P _B , Ne, and θ _TH , for example.

Further, both β (x) and the number of synthesized data n are changed between the normal state and the transient state, but either one may be changed.

The functions shown in the flowchart of FIG. 8 may be performed as part of the functions shown in the flowchart of FIG. In other words, the engine transient state detection and constant setting steps S ₃₀ to S ₃₉ may be performed immediately before step S ₁ .

EFFECTS OF THE INVENTION As is apparent from the above, in the ignition timing control device according to the present invention, the finger pressure peak position data is obtained for each engine cycle from the finger pressure signal indicating the change in the cylinder internal pressure of the internal combustion engine, and is sequentially stored and then synthesized. Since the ignition angle is controlled based on the combined data value that reflects the past history,
The fluctuation of the ignition angle becomes gentle in normal times, the engine operation stability is obtained, and the number of data to be combined is reduced compared to normal times in the transient state of the engine so that the fluctuation of the finger pressure peak position can be quickly responded. ing.

[Brief description of drawings]

FIG. 1 is a graph illustrating changes in internal pressure of an engine cylinder, FIG. 2 is a circuit diagram showing an embodiment of the present invention, FIG. 3 is a signal waveform diagram showing the operation of the apparatus of FIG. 2, FIG. FIG. 5 is a flow chart showing an operation program of a portion constituted by the microprocessor of the apparatus of FIG. 2, FIGS. 6 to 7 are flow charts showing an operation mode program of the ignition angle setting circuit of FIG. 2, and FIG. The figure is a flow chart showing a subroutine incorporated in the ignition angle setting circuit for detecting a transient state of the engine and performing control different from the normal state during the transient state of the engine. Explanation of symbols of main parts 8 …… Ignition setting circuit 9 …… Ignition command circuit 10 …… Latch circuit 11 …… Decoder SW …… Ignition switch T …… Ignition transformer

Claims (1)

[Claims] 1. A reference position signal generating means for generating a reference position signal each time the engine rotation angular position of the internal combustion engine reaches the reference angular position, and a finger pressure signal generating means for generating a finger pressure signal representing an engine cylinder internal pressure. Peak position detecting means for sequentially generating a finger pressure peak position data signal representing the maximum peak position of the finger pressure signal from the generation of the reference position pulse to the next reference position pulse, and the ignition angle is sequentially set based on the finger pressure peak position data signal. An ignition timing control device for an internal combustion engine, comprising an ignition angle setting means and an ignition command means for instructing engine ignition at an ignition angle set by the ignition angle setting means, wherein the ignition angle setting means comprises the finger pressure peak position data. Storage means for sequentially storing the data values of the signals and a synthetic data obtained by synthesizing a plurality of data values stored in the storage means. The internal combustion engine is in a transient state, including a synthesizing means for obtaining a data value and an ignition angle adjusting means for advancing or retarding the ignition angle based on the synthesized data value as a new acupressure peak position data signal. In this case, the ignition timing control device for an internal combustion engine is characterized in that the number of data values to be combined is reduced.