JPS6329059A - Ignition timing controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To make knock occurrence frequency maintainable in spite of a variation in engine speed, by operating plural types of knocking occurrence rates with the operation factor varied according to the engine speed and thereby setting a timing advance correction value. CONSTITUTION:The table value stored in a memory 36c from the engine speed detected via a crank angle sensor 20 is retrieved by a central processing unit 36b at a control unit 36 whereby a reference knock occurring ignition number, a timing advance judging ignition number and a timing advance stand-by ignition number are selected. And, whether there is knocking or not is confirmed from output of a knock sensor 32, and when no knocking occurs there, the knock occurrence factor subtracting the reference knock occurring ignition number by the timing advance judging ignition number is operated. When this knock occurrence factor exceeds the specified value, timing advance correction is stopped, but when it is less than the specified value, the elapse of the timing advance stand-by ignition number is judged and this timing advance correction takes place. With this constitution, even if the engine speed is varied to some extent, knock occurrence frequency is equalizable.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an ignition timing control device for an internal combustion engine, and more specifically, it detects and avoids knocking, and performs advance angle correction after knocking based on the engine operating state. The present invention relates to an ignition timing control device for an internal combustion engine configured to take into consideration the ignition timing control.

(Prior art) Conventional ignition timing control devices for internal combustion engines also detect knocking and correct the ignition timing. The number is fixed uniformly throughout all operating conditions of the engine,
Waiting for the number of ignitions to elapse before starting to advance the angle. One example of this is the technique described in Japanese Patent Application Laid-open No. 55-91765.

(Problem to be solved by the invention) When an internal combustion engine is running at low speeds, it is desirable to ignite near trace knock in order to obtain optimal output, but when running at high speeds, frequent knocks can damage the engine and reduce its durability. It is necessary to take this into consideration and limit it to below. Therefore, the second
As shown in the figure, it is desirable to suppress the knock occurrence frequency level during steady running to below the knock occurrence reference frequency (solid line a), which corresponds to the trace knock described above and is determined by engine characteristics and inversely proportional to engine speed ( Dashed line b). On the other hand,
During transient operation, especially during sudden acceleration, the knock frequency must increase slightly due to the increase in output, but it is necessary to suppress this to below a predetermined limit to protect the engine.
- Dot-dashed line C). Therefore, when determining the advance angle correction after knocking is avoided, the knock occurrence frequency is changed in consideration of the engine rotation speed, and multiple types of knock occurrence frequency levels are set according to changes in steady operation and transient operation. By doing so, it is possible to control the knock occurrence frequency to be uniform even if the engine speed increases or decreases, it is possible to obtain the optimum output and drivability, and it is possible to have a positive effect on the engine itself.

However, since the prior art uses a uniform advance method, the knocking frequency varies as the engine speed changes, making it difficult to perform optimal control as described above.

Therefore, an object of the present invention is to eliminate such drawbacks of the prior art, and to maintain an optimum knock occurrence frequency despite changes in engine speed, and to perform advance angle correction that quickly responds to changes in engine operating conditions. An object of the present invention is to provide an ignition timing control device for an internal combustion engine that makes it possible to control the ignition timing of an internal combustion engine.

(Means and operations for solving the problems) In order to achieve the above object, the present invention includes an operating state detecting means 10 for detecting the operating state of the engine, as shown in FIG. A basic ignition timing calculation means 12 that inputs the output and calculates the basic ignition timing of the engine, a knocking detection means 14 that detects knocking occurring in the engine combustion chamber, and inputs the outputs of the knocking detection means and the basic ignition timing calculation means. an internal combustion engine comprising a knocking correction amount calculating means 16 for correcting the basic ignition timing by a predetermined amount at the time of knocking, and an ignition means 18 for inputting the output of the knocking correction amount calculating means and igniting the air-fuel mixture in the engine combustion chamber. In the ignition timing control device, a plurality of knocking occurrence rates corresponding to engine operating conditions are calculated to determine an advance angle correction value after knocking is avoided, and a calculation coefficient for the knocking occurrence rate is varied depending on the engine speed. It was configured as follows.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a block diagram of a device according to the invention. In the figure, reference numeral 20 indicates a crank angle sensor disposed near a rotating part of the internal combustion engine 22, which detects the rotation angle of the crankshaft accompanying the vertical movement of the piston 24. A negative pressure sensor 28 is disposed downstream of the throttle valve 26 in the air introduction path of the internal combustion engine 22 to detect the load state of the engine. These crank angle sensor 20 and negative pressure sensor 28 constitute the aforementioned operating state detection means 10.

The internal combustion engine 22 is further provided with a knock sensor 32 in the cylinder head 30 to detect the combustion pressure in the combustion chamber 34 . The output of the knock sensor 32 is inputted to a control unit 36, where only the knocking frequency is extracted by a bandpass filter 38, and then inputted to a knocking detection circuit 40 consisting of a comparator, etc., where it is compared with a predetermined level. The presence or absence of knocking is detected. The knocking detection circuit 40, knock sensor 32, and band pass filter 38 constitute the knocking detection means 14 described above.

The control unit 36 has an input/output interface 36aSC
It is mainly composed of a microcomputer consisting of a PU 36b and a memory 36c, and functions as the basic ignition timing calculation means 12 and the knocking correction amount calculation means 16 described above. The output of the aforementioned knocking detection circuit 40 is input to the CPU 36b of the control unit 36, and the output of the crank angle sensor 20 is also input after being waveform-shaped by a waveform shaping circuit 42. The outputs of 28 are also digitally converted by the A/D conversion circuit 44 and input, and the control unit 36 calculates the basic ignition timing and knocking correction amount according to these outputs.

The ignition device 18, which is the above-mentioned ignition means, is provided at the next stage of the control unit 36, and ignites the air-fuel mixture in the combustion chamber 34 via the spark plug 46 in accordance with the output of the control unit 36.

Next, the operation of the apparatus according to the present invention will be explained with reference to the flow chart of FIG.

First, in step 50, a basic ignition timing θb is calculated. This includes the crank angle sensor 20 and the negative pressure sensor 28.
Based on the output of , the basic ignition timing control value table stored in the memory 36c of the control unit 36 is searched and calculated. Note that corrections other than the knocking correction may be added as appropriate based on the output of a water temperature sensor (not shown) or the like.

Next, in step 52, from the value of the engine rotation speed N detected through the crank angle sensor 20, the reference knock occurrence ignition number 1kr, the advance angle determination ignition number In, and the advance angle standby ignition number I are determined.
Select i1. This is for calculating the frequency of knock occurrence, which will be described later. FIG. 5 shows these values which are varied depending on the engine speed, and these values are stored in the memory 36c of the control unit 36 and are appropriately selected from the engine speed. The characteristic curve of this value shown in FIG. 5 was determined based on the above-mentioned knock frequency level shown in FIG. , 1/1w corresponds to the steady-state knock occurrence frequency level (FIG. 3b). In this way, the advance standby ignition number 1 type also means that one knock occurrence is allowed per the ignition number, and can be understood as the reciprocal value of the knock occurrence rate.

Next, in step 54, it is determined whether or not knocking is occurring this time, and if knocking is occurring, in step 56, the knock correction amount θkc is retarded by one degree (in addition, in this flow chart, subtraction means retardation, Addition means advance angle. Also, the knock correction amount θkc is set to the initial value ゛O゛)
.

If knocking has not occurred, then in step 58 the knocking occurrence rate Ikr/In is determined. As mentioned above, this knock occurrence rate is during transient driving,
The reference number of knock occurrence ignitions selected in step 52 is 1 kr/
Compare the value calculated by the number of ignitions for advance judgment In with the value calculated by the actual number of ignitions for knock occurrence 1ka/number of ignitions for advance judgment In, and if Ika/In exceeds Ikr/In, advance the number of ignitions In. Correction is canceled (step 60).

If the knock occurrence rate is less than a predetermined value in step 58, then in step 62, it is determined whether the advance angle standby ignition number 1-, which is the reciprocal of the knock occurrence rate during steady running, has elapsed, and if it has not elapsed, advance angle correction is performed. It is stopped, and if it has elapsed, the advance angle is corrected by 1 degree (step 60.64). Finally, step 6
6, the basic ignition timing θb is changed to the corrected ignition timing θkc (
(positive or negative value) to determine the ignition timing θig.

Fig. 6 shows an example of control based on this flow chart. In the same figure, if time A'° is the present moment and the standard number of knock occurrence ignitions 1kr is 2, then the period (ignition Since the actual number of knocks that occurred in (number) In is one, the transient knock occurrence rate (Ika/In = L/Iri) in step 58 is less than the predetermined value (Ikr/ln = 2/In), If it is assumed that the predetermined advance standby ignition number Iw has passed in the subsequent steady-state knock occurrence rate determination step 62, the advance angle will be corrected by 1 degree. That is, in the figure, before the start of section In, knocking occurs frequently and it can be assumed that the engine is running in a transient state, but by inserting the transitional knock occurrence rate judgment step 58, the knocking frequency is temporarily lowered and the engine is restarted. It can be protected. In the conventional technology, such a judgment step is not involved, and the number of advance standby ignitions is uniform, so the wait time is short at high rotation speeds, so the advance is immediately performed, so that knocking, retardation, and advance timing are prevented. However, there was an inconvenience in that the knocking occurred repeatedly and had a negative impact on the engine. The present invention eliminates this disadvantage by inserting the transient judgment step 58, and increases or decreases the advance standby ignition number in the subsequent steady state judgment step 62 in proportion to the change in engine speed.
The frequency of knock occurrence can be made uniform both in the high rotational speed region and in the low rotational speed region, and optimal control can be performed.

(Effects of the Invention) The present invention is configured to determine an advance angle correction value by calculating multiple types of knocking occurrence rates corresponding to engine operating conditions, and to vary the calculation coefficient of the knocking occurrence rate depending on the engine speed. As a result, the frequency of knocking occurrence is uniform even when the engine speed changes, and even when the frequency of knocking increases, such as during transient driving, the frequency of knocking can be reduced, resulting in optimal output and improved drivability. At the same time, the engine ignition timing can be controlled optimally, with the advantage that there is no risk of damage to the engine and its durability is improved.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to the claims of the present invention, Fig. 72 is an explanatory diagram of the control method of the present invention, Fig. 3 is a block diagram showing the configuration of the device according to the present invention, and Fig. 4 is a flowchart showing its operation.・Chart: FIG. 5 is an explanatory diagram showing calculation coefficients of the knock occurrence rate, and FIG. 6 is an explanatory diagram showing an example of control based on the flow chart of FIG. 4. 10... Operating state detection means (crank angle sensor 20,
Negative pressure sensor 28), 12... basic ignition timing calculation means,
14...Knocking detection means (knock sensor 32, bandpass filter 38, knocking detection circuit 40), 1
6... Knocking correction amount calculation means, 18... Ignition means (ignition device), 36... Control unit

Claims (1)

[Scope of Claims] a. Operating state detection means for detecting the operating state of the engine; b. Basic ignition timing calculation means for calculating the basic ignition timing of the engine by inputting the output of the operating state detection means; c. Engine combustion. knocking detection means for detecting knocking occurring in the chamber; d; knocking correction amount calculation means for inputting the outputs of the knocking detection means and the basic ignition timing calculation means to correct the basic ignition timing by a predetermined amount at the time of knocking; e. In an ignition timing control device for an internal combustion engine equipped with an ignition means for inputting the output of the knocking correction amount calculation means to ignite the air-fuel mixture in the engine combustion chamber, a plurality of types of knocking occurrence rates corresponding to engine operating conditions are calculated. An ignition timing control device for an internal combustion engine, characterized in that an ignition timing control device for an internal combustion engine is configured to calculate and determine an advance angle correction value after knocking avoidance, and to vary a calculation coefficient for the knocking occurrence rate depending on the engine speed.