JPH0368225B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition timing control device for an internal combustion engine that controls knocking in the internal combustion engine.

[Conventional technology]

It is desirable to set the ignition timing of an internal combustion engine to be the most efficient for the operating conditions of the engine.
Minimum advance for Best
It is desirable to set the ignition timing to be advanced so that it approaches the torque.

However, excessive advance of the ignition timing causes excessive knocking, which not only reduces operating efficiency but also causes damage to the engine.

Therefore, it is necessary to have an ignition timing control device that controls the ignition timing to the optimum by setting the standard ignition advance characteristic in advance to the advance side in order to bring it closer to MBT, and then performing timely retard control in response to the occurrence of knocking. Become.

FIG. 2 is a block diagram showing a conventional ignition timing control device. In the figure, 1 is an acceleration sensor that is attached to the engine and detects the vibration acceleration of the engine, 2 is a frequency filter that passes a signal component with a high frequency that is sensitive to knocking out of the output signal of the acceleration sensor 1, and 3 is a frequency filter. Among the output signals of 2, an analog gate blocks noise that becomes a disturbance wave when detecting a knock, 4 is a gate timing controller that instructs the analog gate 3 to open or close according to the timing of occurrence of disturbance noise, and 5 is a gate timing controller for other than knocking. A noise level detector that detects the level of mechanical vibration noise of the engine; 6 a comparator that compares the output voltage of the analog gate 3 with the output voltage of the noise level detector 5 and generates a knock detection pulse; 7 a comparator 6 is an integrator that integrates the output pulse and generates an integrated voltage according to the knocking intensity; 8 is a phase shifter that shifts the position of the reference ignition signal according to the output voltage of integrator 7; 9 is a preset ignition signal. A rotation signal generator that generates an ignition signal according to the advance angle characteristic; 10 a waveform shaping circuit that shapes the output of the rotation signal generator 9; and 11 a waveform shaping circuit that simultaneously controls the closing angle of energization of the ignition coil 12; 11 a phase shifter; This is a switching circuit that cuts off and on the power supply to the ignition coil 12 based on the output signal of the device 8. Here, the output of the comparator 6 is fed back to the noise level detector 5 to prevent the noise level from increasing due to the knock signal.

FIG. 3 shows the frequency characteristics of the output signal of the acceleration sensor 1. In FIG. 3, A shows the case where there is no knocking, and B shows the case where knocking occurs.

The output signal of the acceleration sensor 1 includes a knock signal (a signal generated due to knocking), mechanical noise from other engines, and various noise components on the signal transmission path, such as ignition noise. Comparing A and B in FIG. 3, it can be seen that the knock signal has unique frequency characteristics.

Although this distribution differs depending on the engine or the mounting position of the acceleration sensor 1, there is a clear difference in the distribution depending on the presence or absence of knocking in each case. Therefore, by passing the frequency component of this knock signal, the noise of other frequency components can be suppressed, and the knock signal can be detected efficiently.

4 and 5 show the operating waveforms of each part in FIG. 2, and the same symbols indicate the waveforms of the same parts.
The figure shows a mode in which engine knocking does not occur, and FIG. 5 shows a mode in which engine knocking occurs.

Next, the operation of the ignition timing control device for an internal combustion engine shown in FIG. 2 will be explained. The ignition signal generated by the rotation signal generator 9 in accordance with the ignition timing characteristics set in advance by the rotation of the engine is waveform-shaped by the waveform shaping circuit 10 into an opening/closing pulse having a desired closing angle.
The switching circuit 11 is driven via the phase shifter 8 to cut off and cut off the power supply to the ignition coil 12, and the engine is ignited and operated by the ignition voltage of the ignition coil 12 generated when the energizing current is cut off. Engine vibrations occurring during operation of the engine are detected by an acceleration sensor 1.

If knocking is not occurring in the engine, engine vibration due to knocking will not occur, but due to other mechanical vibrations, the output signal of the acceleration sensor 1 may be affected by mechanical noise or ignition timing as shown in Figure 4a. Ignition noise that rides on the signal transmission path occurs in F.

By passing this signal through the frequency filter 2, the mechanical noise component is considerably suppressed as shown in Figure 4b, but the ignition noise component is strong and is output at a high level even after passing through the frequency filter 2. may be done. If this continues, the ignition noise will be mistakenly recognized as a knock signal, so the analog gate 3 adjusts the ignition timing based on the output of the gate timing controller 4 (FIG. 4c), which is triggered by the output of the phase shifter 8. The gate is closed for a period of time to block ignition noise. Therefore, only low-level mechanical noise remains in the output of the analog gate 3, as shown in FIG. 4(d).

On the other hand, the noise level detector 5 responds to changes in the peak value of the output signal of the analog gate 3, and in this case, has the characteristic of being able to respond to relatively gentle changes due to the peak value of normal mechanical noise. A DC voltage slightly higher than the peak value of the noise is generated (FIG. 4d, b). This DC voltage is generated using a time constant circuit.

Therefore, as shown in FIG. 4d, the output of the noise level detector 5 is larger than the average peak value of the output signal of the analog gate 3, so the output of the comparator 6 for comparing these is as shown in FIG. Nothing is output as shown in e, and all noise signals are eventually removed.

Therefore, the output voltage of the integrator 7 remains zero as shown in FIG. 4f, and the phase shift angle by the phase shifter 8 (the phase difference between input and output (FIG. 4g and h)) also becomes zero.

Therefore, the opening/closing phase of the switching circuit 11 driven by this output, that is, the intermittent phase of energization of the ignition coil 12, is in phase with the reference ignition signal output from the waveform shaping circuit 10, and the ignition timing is the same as the reference ignition timing. Become.

Furthermore, when knocking occurs, the output of the acceleration sensor 1 includes a knocking signal around a certain time delay from the ignition timing as shown in FIG. 5a, and the signal after passing through the frequency filter 2 and analog gate 3 As shown in Fig. 5d, the knock signal is largely superimposed on the mechanical noise.

Among the signals that have passed through the analog gate 3, the rise of the knock signal is steeper than that of the noise signal, so the response of the output voltage level of the noise level detector 5 to the knock signal is delayed. As a result, the inputs of the comparator 6 become A and B as shown in FIG. 5D, respectively, and a pulse is generated at the output of the comparator 6 as shown in FIG. 5E. This pulse is then fed back to the noise level detector 5, and the output of the noise level detector 5 is controlled so as not to become large due to the knock signal even if the knock signal is subsequently inputted.

An integrator 7 integrates the pulses and generates an integrated voltage as shown in FIG. 5f. Since the phase shifter 8 shifts the phase of the output signal of the waveform shaping circuit 10 (Fig. 5g (reference ignition signal)) to the delayed side in accordance with the output voltage of the integrator 7, the phase shifter 8 The phase of the output of the switching circuit 11 lags behind the phase of the reference ignition signal of the waveform shaping circuit 10, and the phase is shown in FIG. 5h.
to drive. As a result, the ignition timing is delayed and knocking is suppressed. In the end, these fourth
Even if the states shown in Figs. and 5 are repeated and the knock signal is continuously input, optimal ignition timing control is performed.

As described above, since the ignition timing control device for an internal combustion engine shown in FIG. 2 calculates the retard angle of the ignition signal using an electronic circuit, precise angle control is possible.

[Problem that the invention seeks to solve]

However, according to such an ignition timing control device, the transmission installed in the engine is automatically controlled (so-called automatic system, hereinafter referred to as AT).
method), the output of the noise level detector 5 (see Figs. 4 and 5) is used during the gear ratio switching control.
Due to the response delay shown in d-b of the figure, the knock detection is not performed properly as described above, resulting in a problem that insufficient control may occur.

This problem will be explained with reference to FIG. The vertical axis of FIG. 6a shows the engine rotation speed, the horizontal axis shows time, and the vertical axis of FIG. The axis shows time. Here, before time t ₁ , the characteristics are during acceleration, and from time t ₁ to time t ₂ are the characteristics during gear ratio switching control, which is the so-called shift-up time (when the gear ratio is changed to the first
From time t2 onwards, the characteristics are shown during acceleration after the shift _- up.

The characteristics of the output of the noise level detector 5 are set so that the voltage corresponds to the rotation of the engine. In addition, the output of the noise level detector 5 is obtained by obtaining a DC voltage from the output of the analog gate 3, and is composed of a rectifier circuit, a smoothing circuit, or an amplifier circuit, and is inevitably delayed. It has the same output characteristics. In order to obtain a more stable DC voltage, the time constant of the smoothing circuit is preferably set to a large value. Therefore, for example, when the rotation of the engine suddenly changes, the output of the noise level detector 5 does not become a voltage corresponding to the rotation speed of the engine due to the delay.

In FIG. 6, during acceleration before time _t1 , the engine speed increases relatively slowly, and the output voltage of the noise level detector 5 is a predetermined voltage value corresponding to the engine speed. Next, at time _t1 , gear ratio switching control is started to shift up, and the control ends at time _t2 . In other words, when the engine speed reaches the upper limit of N ₂ (usually 5000 to 6000 rpm) during acceleration, a shift up starts, and at time t ₂ when the gear ratio switching control ends, the engine speed suddenly drops to N ₁ (usually
around 4000rpm). Therefore, the output voltage of _the noise level detector ₅ is
It needs to be set so that V ₁ and V ₂ ,
When the engine speed suddenly changes as described above, the output of the noise level detector 5 becomes a voltage larger than V ₁ corresponding to the engine speed N ₁ at time t ₂ (Fig. 6b) due to the response delay. V ₃ ). in the end,
Due to this delay, the output of the noise level detector 5 is
The desired characteristic corresponding to the engine speed (see Fig. 6b)
Vr ₁ ) has a gentler characteristic (Vr ₂ in FIG. 6b), and knock detection will not be performed properly. If knock detection is not performed, the knock pulse from the comparator 6 is transmitted to the noise level detector 5.
Therefore, the output of the noise level detector 5 is also increased by the knock signal of the output of the analog gate 3, and at this time, the noise level becomes increasingly abnormally high voltage after time _t2 . In this way, knock detection becomes even more difficult.

As described above, in the conventional ignition timing control device shown in FIG. 2, the desired knock detection is not performed due to the delay in response of the output of the noise level detector 5 when controlling the gear ratio switching of the transmission installed in the engine. There was a problem that the knock control was not performed properly.

The present invention has been made to solve these problems, and its purpose is to provide an internal combustion engine that can perform appropriate knock control even during gear ratio switching control of the transmission. An object of the present invention is to provide an ignition timing control device.

[Means for solving problems]

In order to achieve such an object, the present invention determines the response characteristics of the time constant circuit of the knock signal discriminating means based on the speed ratio switching control characteristics of the transmission installed in the internal combustion engine. .

[Effect]

Therefore, according to the device according to the present invention, if the discrimination response characteristics of the knock signal, such as the response speed of the noise level voltage, are determined so that the speed is sufficiently high with respect to the speed ratio switching control speed of the transmission, the engine A noise level voltage corresponding to the rotational speed is always obtained, and knock detection can be performed reliably even after the speed ratio switching control is completed.

〔Example〕

Hereinafter, the ignition timing control device for an internal combustion engine according to the present invention will be explained in detail. FIG. 1 shows an example of a circuit for setting the responsiveness of the noise level voltage in this ignition timing control device, and is a smoothing circuit that constitutes the noise level detector 5 in FIG.
In the figure, 13 is an input terminal to which a rectified signal is input, 14 is an output terminal to which a smoothed signal is output, and 1
5 and 16 are resistors, and 17 is a capacitor.

As mentioned above, the noise level voltage is obtained as a DC voltage by rectifying, smoothing, or amplifying the output of the analog gate 3. A rectified signal is input to the input terminal 13, and the capacitor 17 is charged via the resistor 15. The charge of this capacitor 17 is discharged via the resistor 16. In this way, a smoothed voltage is obtained and output from the output terminal 14.

By the way, since the knock signal in a normal internal combustion engine has a frequency component of 5 to 10 kHz, the frequency filter 2 is set to select and output this 5 to 10 kHz component. Therefore, a smoothing circuit with a large time constant is not required to rectify and smooth the output of the analog gate 3 to obtain a DC voltage (that is, a smoothing circuit with a slow response is not required). On the other hand, the speed ratio switching response of an AT type transmission is
Since it is on the order of 100 ms, the time constant of the smoothing circuit shown in FIG. 1 may be set between several ms and several 100 ms. In the inventor's confirmation using an actual vehicle, if the smoothing circuit is set to have a fast response that is approximately one-third or less of the speed ratio switching response of the transmission, noise will be eliminated even when detecting a knock after the speed ratio switching is completed. It was confirmed that the level voltage had sufficient responsiveness compared to the engine speed. Therefore, it is possible to reduce the capacitance of the capacitor 17 to provide a noise level voltage that has a sufficiently fast response to the speed ratio switching control speed of the transmission, and at the same time, by reducing the capacitance of the capacitor 17, it is possible to downsize and reduce the cost of the control circuit. I can do it.

〔Effect of the invention〕

As explained above, according to the ignition timing control device for an internal combustion engine according to the present invention, the response characteristics of the time constant circuit of the knock signal discriminating means are determined based on the speed ratio switching control characteristics of the transmission installed in the internal combustion engine. Therefore, if the discrimination response characteristics of the knock signal are determined so that the speed is sufficiently faster than the speed ratio switching control speed, knock detection can be performed reliably even at the end of the speed ratio switching control. I can,
Appropriate knock control becomes possible.

Further, in conjunction with this, it is possible to reduce the capacity of the constituent electronic parts, and the excellent effect of reducing the size and cost of the control circuit can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a circuit for setting the responsiveness of a noise level voltage in an ignition timing control device for an internal combustion engine according to the present invention, and FIG. 2 is a block diagram showing a conventional ignition timing control device. Figure 3 is a diagram showing the frequency characteristics of the output signal of the acceleration sensor, Figures 4 a to h are diagrams showing the waveforms of each part in Figure 2 when engine knocking has not occurred, and Figures 5 a to
h is the second value when engine knocking occurs.
FIG. 6 is a graph showing changes in engine speed and noise level voltage during gear ratio switching control. 1... Acceleration sensor, 2... Frequency filter,
3... Analog gate, 4... Gate timing controller, 5... Noise level detector, 6... Comparator, 7... Integrator, 8... Phase shifter, 9... Rotation signal generator, 10...Waveform shaping circuit, 11...Switching circuit, 12...Ignition coil, 15,1
6...Resistor, 17...Capacitor.

Claims (1)

[Scope of Claims] 1. A reference voltage is generated using an acceleration sensor that detects vibration acceleration of an internal combustion engine and a time constant circuit from the output of this acceleration sensor, and a knocking signal is generated by comparing this reference voltage with the acceleration sensor output. knock signal discriminating means for selecting components; reference ignition timing signal generating means for generating a reference ignition timing signal; and phase shifting means for shifting the phase of the reference ignition timing signal in accordance with the output of the knock signal discriminating means; In the ignition timing control device for an internal combustion engine, the ignition timing control device includes a switch means for intermittent power supply to the ignition coil in accordance with the output of the phase shift means, and the above-mentioned switch is configured to control the timing based on the gear ratio switching control characteristics of the transmission installed in the internal combustion engine. An ignition timing control device for an internal combustion engine, characterized in that the response characteristic of a time constant circuit of a signal discriminator is determined. 2. The knock signal discrimination means includes a comparator, and the responsiveness of the comparison reference voltage of the comparator is determined based on the transmission ratio switching transient characteristic. Ignition timing control device for internal combustion engines. 3. Claim 2, characterized in that the response of the comparison reference voltage of the comparator is made to have a fast transient characteristic of one-third or less of the speed ratio switching response speed of the transmission.
An ignition timing control device for an internal combustion engine as described in 2.