JPH0261625B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to a device that controls ignition timing based on the octane number of gasoline, which is the fuel thereof.

[Prior art]

It is known that the octane number of gasoline has a strong correlation with the knock resistance of an internal combustion engine. That is, the higher the octane number of gasoline used, the less likely the internal combustion engine will knock.

FIG. 1 shows the ignition timing versus output torque characteristics of an internal combustion engine using commercially available regular gasoline and premium gasoline (which has a higher octane number than regular gasoline). Point A is the knock limit point when regular gasoline is used, and point B is the knock limit point when premium gasoline is used.If the ignition timing is advanced beyond the knock limit point at each point, knock will occur, and as the timing is advanced, It starts to occur on a large scale. As is clear from this figure 1, when using premium gasoline, the ignition timing is set to B.
Since the angle can be advanced up to a point, it is possible to improve the output torque compared to when regular gasoline is used.

FIGS. 2 and 3 show ignition timing characteristics showing the ignition timing at these knock limit points A and B with respect to the rotational speed and load of the internal combustion engine, respectively. As shown in these figures, if the rotation speed or load is the same, the ignition timing can be advanced when using premium gasoline.

As described above, when the gasoline used in an internal combustion engine is converted to regular gasoline and premium gasoline or mixed, it is possible to improve the engine output by adjusting the ignition timing according to the type of gasoline.

By the way, the characteristics of the conventional ignition timing control devices used in the internal combustion engines of automobiles currently on sale are based on regular gasoline, so it is not possible to simply use premium gasoline in such engines. However, the output of the engine will not improve, and there will be no benefit from using premium gasoline unless you somehow change the ignition timing to the advanced side.

In addition, by using knock control technology that detects engine knock and controls the ignition timing to the knock occurrence limit point, the regulation is adjusted based on the basic ignition timing characteristics set for premium gasoline (for example, point B in Figure 1). When using gasoline, it is conceivable to perform knock control as appropriate and retard the ignition timing to point A in FIG. However, in this case, since the ignition timing retard control width (the angular width between points A and B in Figure 1) is large, when a knock occurs in the engine, the ignition timing is
There was a problem in that a large knock occurred during control from point B to point A in the figure.

[Summary of the invention]

The present invention has been made with attention to the above points,
A knock sensor is used to detect knocks occurring in the engine, and based on the knock occurrence situation, it is determined whether the gasoline used is regular gasoline or premium gasoline, and the advance characteristics of the ignition timing are switched and controlled. , the ignition timing characteristics are set in accordance with the gasoline used, and the control angle width of the knock control is reduced as appropriate to prevent the occurrence of knocks. When switching from the advance setting (when using premium gasoline) to the advance setting (when using premium gasoline), this control suppresses sudden changes in ignition timing to prevent excessive knock from occurring.

[Embodiments of the invention]

FIG. 4 shows an embodiment of the present invention. In FIG. 4, numeral 1 is a knock sensor that is attached to the engine and detects knock vibrations and noise vibrations of the engine; 2 is a knock discriminator that discriminates a knock signal from the detection signal of the knock sensor 1; a band pass filter 21; a noise level detector; 22 and a comparator 23. Here, the detection signal of the knock sensor 1 is input to the band pass filter 21, and the output of the band pass filter 21 is input to the first comparison input of the comparator 23 and the noise level detector 22. The output of the noise level detector 22 is input to the second comparison input of the comparator 23. Reference numeral 3 denotes a retard control voltage generator that generates a retard control voltage in response to the output of a comparator 23 or a pulse generator 20, which will be described later. Reference numeral 4 denotes a reference ignition timing switching determination unit that determines switching of the reference advance characteristic of the ignition timing, and this includes two comparators 41 and 4.
2, two AND gates 43 and 44, an operating range determiner 45, a flip-flop 46, and an initialization circuit 47. Comparators 41 and 42 compare the respective reference voltages V ₁ and V ₂ with the output of the retard control voltage generator 3, and these outputs are input to AND gates 43 and 44, respectively. An operating range determiner 45 determines the operating range of the engine from the outputs of a pressure sensor 5 and a phase shifter 8, which will be described later, and this output is input to AND gates 43 and 44. Flip-flop 46 has a set input, a reset input, and a preset input, to which the outputs of AND gates 43 and 44 and initialization circuit 47 are input, respectively. The initialization circuit 47 outputs a preset pulse when starting the engine, for example. The pressure sensor 5 detects the intake pipe pressure of the engine and converts it into an electrical signal. 6 is an adder that adds the retard control voltage from the retard control voltage generator 3 and the output of the flip-flop 46; 7 is a reference ignition timing signal generator that generates a reference ignition timing signal that provides a reference ignition timing, and a phase shifter; 8 is a phase shifter that shifts the phase of the reference ignition timing signal from the reference ignition timing signal generator 7 to the delayed side according to the signal voltage from the adder 6; The engine is ignited and operated using the high voltage generated in the ignition coil 10 by a switch circuit that turns the coil 10 on and off. Pulse generator 20 generates a pulse in response to the falling edge of the output of flip-flop 46.

5 and 6 show operating waveforms of each part in FIG. 4.

The operation will be explained below.

The knock sensor 1 is of a type that detects vibration acceleration, for example, and is attached to a cylinder block of an engine, etc., and converts mechanical vibrations (knocks and noise vibrations) of the engine into electrical signals. This detection signal is shown in FIG. 5a. The bandpass filter 21 selects a frequency component peculiar to a knock (a frequency component of a signal that appears with the occurrence of a knock) from the detection signal and suppresses noise components other than the knock signal.
Outputs the signal shown in Fig. b. The noise level detector 22 includes, for example, a half-wave rectifier circuit, an averaging circuit,
It is composed of an amplifier circuit, etc., and converts the output signal of the bandpass filter 21 shown in Fig. 5b-a into a DC voltage by half-wave rectification and averaging, and amplifies it with an amplifier. Outputs the DC voltage shown in b. In FIG. 5, the left side of the figure shows a case where no knock has occurred in the engine, and the right side shows a case where a knock has occurred. The output of the noise level detector 22 shown in FIG. The voltage is larger than the signal N, but smaller than the knock signal S of the output of the band pass filter 21 when a knock occurs in the engine shown in the right part of A in FIG. The comparator 23, which compares the voltage between the output of the noise level detector 22 (a in Fig. 5b) and the output of the noise level detector 22 (b in Fig. 5b), generates a pulse signal only for the knock signal when a knock occurs in the engine. Output a signal.
The output of this comparator 23 is shown in FIG. 5c. That is, the pulse signal from the comparator 23 corresponds to the knock signal generated in the engine.

Next, explanation will be given using FIG. 6. Here, the operating waveforms of the engine are shown in three types of operating conditions. The left side of the figure is when the engine starts, the middle part is when premium gasoline is used at the standard ignition timing setting for regular gasoline, and the right side is when the engine is started. Each section shows the case where regular gasoline is used in the standard ignition timing setting for premium gasoline.

The retard control voltage generator 3 is composed of, for example, an integrating circuit, and is shown in FIG. 6 d based on the pulse signal (FIG. 6 c, FIG. 6 n) from the comparator 23 or the pulse generator 20. Generates a retard control voltage such as This retard control voltage falls at a predetermined speed when no pulse signal is input from the comparator 23 or the pulse generator 20. Further, this retard control voltage is input to the comparators 41 and 42, and at the same time is input to the phase shifter 8 via the adder 6, and is used for ignition timing control.

The comparators 41 and 42 respectively compare the retard control voltage from the retard control voltage generator 3 with the reference voltage _V1 or _V2 , and the comparator 41 compares the retard control voltage (see FIG. If d) is higher than the reference voltage _V1 , its output is set to a high level as shown in _FIG . The output is set to a high level as shown in Fig. 6g. Here, the reference voltages V ₁ and V ₂ are
There is a relationship of V ₁ > V ₂ .

The operating range determiner 45 detects the engine's intake pipe pressure and converts it into an electrical signal, detects the engine load condition from the pressure signal from the pressure sensor 5, and detects the engine load condition from the ignition signal from the phase shifter 8. Detects the rotation speed. The operating state of the engine is determined from this operating information. For example, as shown in Figure 7, when setting the reference ignition timing for premium gasoline, when using premium gasoline, the retard control voltage (retard control voltage generator) required to retard the reference ignition timing to the knock limit point is used. Let α be an operating condition in which the output of engine 3) is less than V ₁ and the retard control voltage required to retard the reference ignition timing to the knock limit point is more than V ₁ when regular gasoline is used.
On the other hand, as shown in Figure 8, in the standard ignition timing setting compatible with regular gasoline, the operating conditions are set such that the retard control voltage is less than V ₂ when premium gasoline is used, and more than V ₂ when regular gasoline is used. Let it be β. The operating range determining unit 45 determines the operating range in which these operating conditions α and β are compatible, and when the engine operating state is in a state in which the above conditions α and β are compatible, the output of the operating range determining unit 45 is at a high level. becomes. Therefore, the output of the AND gate 43, which outputs the AND signal of the output of the comparator 41 and the output of the operating range determiner 45, will be at a high level only when regular gasoline is used at the standard ignition timing setting corresponding to premium gasoline. , while comparator 4
The output of the AND gate 44 which outputs the logical product signal of the output of 2 and the output of the driving range determiner 45 becomes a high level only when premium gasoline is used in the standard ignition timing setting compatible with regular gasoline. In other words, when premium gasoline is used in the standard ignition timing setting for regular gasoline, or when regular gasoline is used in the standard ignition timing setting for premium gasoline, the operating state of the engine meets the above operating condition α. β is compatible, and the output of the AND gate 44 or the AND gate 43 becomes a high level only as shown in the center part of FIG. 6k or the right part of FIG. 6j, respectively.

Flip-flop 46 is set when the output of AND gate 43 goes high, and is reset when the output of AND gate 44 goes high.
The initialization circuit 47 generates a presetting pulse (Fig. 6l) when the engine is started, for example.
With this preset pulse, the flip-flop 46
is preset to the set state (left part of Figure 6m). Here, when the flip-flop 46 is set, its output is at a high level, and when it is reset, its output is at a low level. As described above, the flip-flop 46 first receives the preset pulse (sixth pulse) from the initialization circuit 47 when starting the engine.
1), and the output is set to a high level (retard mode compatible with regular gasoline). When the engine is operated in this state, if premium gasoline is used, the knock that occurs in the engine will be below a predetermined level, and the output of the retard control voltage generator 3 will be below V ₂ (center part of Figure 6 d). , in the predetermined operating range (region where the above conditions α and β are compatible), the output of the AND gate 44 becomes a high level (center part of FIG. 6k), the flip-flop 46 is reset, and its output becomes a low level ( (advanced angle mode compatible with premium gasoline) (center part of Fig. 6 m). On the other hand, when regular gasoline is used in the ignition timing setting compatible with premium gasoline (advanced angle mode in which the flip-flop 46 is reset), the knock occurring in the engine exceeds a predetermined value, and the retard control voltage generator 3 The output of the AND gate 43 becomes higher than V ₁ (the right part of Fig. 6 d), and the output of the AND gate 43 becomes a high level in the above-mentioned predetermined operating range (the right part of Fig. 6 j), and the flip-flop 4
6 is set, and its output is set to a high level (retard mode compatible with regular gasoline) (right side of Fig. 6m). The output of flip-flop 46 is input to phase shifter 8 via adder 6, and at the same time is input to pulse generator 20.

The reference ignition timing signal generator 7 outputs a reference ignition timing signal having an advanced ignition timing characteristic corresponding to premium gasoline, which is set according to the engine operating state (rotation speed and load). This is, for example, a signal generated by an ignition signal generator built into the power distributor. The phase shifter 8 converts the reference ignition timing signal into the adder 6.
The phase is controlled to be delayed in time according to the voltage from the output. Therefore, when the output of the flip-flop 46 becomes a high level, the ignition timing characteristic is changed to a delayed side ignition timing characteristic delayed by an angle corresponding to that level. The switch circuit 9 turns on and off the energization of the ignition coil 10 in response to the output of the phase shifter 8, and generates a high voltage for ignition. Therefore, the high voltage generation timing (ignition timing) is controlled by the output of the adder 6 which is input to the phase shifter 8, that is, it is controlled to change in accordance with the high and low levels of the output of the flip-flop, and this changed The ignition timing according to the reference characteristics is further controlled in accordance with the output voltage of the retard control voltage generator 3.

By the way, in the above-described ignition timing switching control, premium gasoline is used when the standard ignition timing is set to a delay side characteristic compatible with regular gasoline, and the standard ignition timing is set to an advanced characteristic compatible with premium gasoline. When the flip-flop 46 is switched to the side, that is, when the flip-flop 46 is brought from the set state to the reset state, the flip-flop 46
When the amount of phase shift in the phase shifter 8 is instantaneously reduced by the output of There is a risk that the engine will enter the knock range and cause an excessive knock that may even damage the engine. Therefore, in the present invention, the output of the flip-flop 46 (Fig. 6 m) is input to the pulse generator 20, and this pulse generator 20 generates the pulse signal shown in Fig. 6 n when the characteristic is switched from the lagging side to the leading side. By applying this pulse signal (n in FIG. 6) as an input signal to the retard control voltage generator 3, the retard control voltage generating circuit 3 is forced to generate the retard control voltage at a predetermined level in the same manner as the knock signal. (center part of Fig. 6 d), and by increasing the amount of retardation in the phase shifter 8, the sudden ignition timing becomes large when switching from the retard side to the advance side of the standard ignition timing characteristic. This prevents the advance angle from fluctuating and changes gradually to prevent excessive knocks from occurring in the engine. Since this retard control voltage generator 3 has a characteristic that the output level attenuates by a predetermined number for normal knock control, it is possible to gradually change the ignition timing to the advance side by utilizing this characteristic. It can be easily configured without requiring any special circuit configuration.

〔Effect of the invention〕

As explained above, according to the present invention, by detecting a knock occurring in the engine and controlling the standard ignition timing to be delayed or advanced depending on the occurrence situation, regular gasoline or premium gasoline can be used. In the ignition system that is set to the corresponding ignition timing characteristics, the actual ignition timing is gradually changed to prevent sudden changes in the standard ignition timing when switching from the delayed side to the advanced side of the standard ignition timing. This prevents the ignition timing from suddenly entering the knock range when changing the characteristics.It not only allows you to set an appropriate standard ignition timing for the engine that corresponds to the gasoline used, but also prevents the engine from excessive knocking when changing the standard ignition timing characteristics. Furthermore, the retard control signal generation circuit for knock control is shared to prevent sudden fluctuations in ignition timing at the time of switching, so the configuration for this purpose is simple and does not require any special configuration. This provides an excellent effect in that it can be configured as follows.

[Brief explanation of drawings]

Figures 1, 2, 3, 7, and 8 are characteristic diagrams of the engine, Figure 4 is a block circuit diagram of an embodiment of the present invention, and Figures 5 and 6 are Figure 4 shows operating waveform diagrams of each part. In the figure, 1 is a knob sensor, 2 is a knob discriminator,
3 is a retard control voltage generator, 4 is a reference ignition timing switching determination section, 5 is a pressure sensor, 6 is an adder, 7 is a reference ignition timing signal generator, 8 is a phase shifter, 9 is a switch circuit, 10 is a Each represents an ignition coil.

Claims (1)

[Claims] 1. A knock sensor that is attached to an engine and generates an electrical signal corresponding to the knock vibration and noise vibration of the engine, a knock signal discrimination means that discriminates the knock signal component from the electric signal, and a reference based on the output of this knock signal discrimination means. Ignition timing switching determining means for determining switching of ignition timing characteristics, retard control signal generating means for generating a retard control signal based on the output of the knock signal determining means, the ignition timing switching determining means and retard control signal means. receiving the output of the ignition timing switching determination means, switching between two preset standard ignition timing characteristics of an advanced side and a delayed side according to the output of the ignition timing switching determination means;
ignition timing control means for controlling the ignition timing in accordance with the reference ignition timing characteristic selected by this switching according to the retard control signal; Ignition timing control for an internal combustion engine, comprising means for generating a retard control signal that gradually changes the actual ignition timing by applying a predetermined input signal to the retard control signal generating means when switching the reference ignition timing characteristic to Device.