JPS63212768A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To perform the correct knocking control by providing multiple filters having different center frequencies and selecting the knocking signal component from the output of an acceleration sensor and controlling the ignition timing in response to the output. CONSTITUTION:Only the frequency component with high sensitivity to knocking among the engine vibration acceleration signal from an acceleration pickup 11 passes through a frequency filter 13. That is, the center frequency of the frequency filter 13 is switched in response to the engine rotating speed. Various noises in the output signal are cut off by an analog gate 15. The mechanical vibration noise of an engine is detected by a noise detector 16 and compared with the output voltage of the analog gate 15 by a comparator 17 to generate knocking detecting pulses. The output is integrated by an integrator 18, the ignition signal for an ignition system 20 is outputted by an ECU 19 in response to the output voltage corresponding to the knocking strength, and the knocking preventing control is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) This invention relates to an ignition timing control device for an internal combustion engine.

(Prior Art) The ignition timing of an internal combustion engine is set in such a way as to provide the best efficiency for the operating condition of the engine. In general, M B T (Mln
lmus advance for Be5t Tor
It is desirable to set the ignition timing so that it approaches que).

(Problems to be Solved by the Invention) However, many conventional ignition timing control devices are mechanical, and the ignition advance characteristics are not stable due to product variations or changes over time. Therefore, the actual ignition timing is set much later than the desired ignition advance characteristic to prevent knocking.

This worsens the efficiency of the institution. In addition, even if an ignition timing control device that does not have variations or changes over time is used, the knocking phenomenon is affected by the engine's intake air temperature, humidity, air-fuel ratio, etc., so under certain conditions there will be an ignition timing control device that does not cause knocking. Even if it is set to , knob king may occur under different operating conditions.

Therefore, if knocking is detected and control is performed to delay the ignition timing if knocking occurs, knocking will almost never occur even if there is an error in the ignition advance characteristics due to mechanical variations or differences in operating conditions as described above. You can adjust the ignition timing to avoid this. There are several methods to detect knocking, such as measuring the pressure in the combustion chamber, measuring the vibration acceleration of the engine, and measuring the sound generated by the engine. Considering this, the most practical method is to measure the vibration acceleration of the engine. However, in this method, mechanical vibration noise generated by the engine is simultaneously received along with the knock signal, so it is necessary to select the knock signal from the mechanical vibration noise.

Conventional knock controllers eliminate noise and increase knock sensitivity by passing the output of an acceleration sensor (knock sensor) through a band-pass filter tuned to a frequency unique to knocks. However, depending on the specifications of the engine, there are rotation speeds and loads where the frequency at which it is easy to detect mechanical vibrations other than knock and the frequency unique to knock match, making it impossible to distinguish between noise and knock.

The purpose of this invention is to detect a knock signal from the output of an engine's vibration acceleration sensor without being interfered with by various noise components, and to obtain the optimal ignition timing by controlling the ignition timing according to the knock signal. That is.

[Structure of the invention] (Means and effects for solving the problem) One acceleration sensor that detects vibration acceleration of an internal combustion engine, and noise signal components of the output of this acceleration sensor are removed and knocking signal components are selected. An internal combustion engine comprising a plurality of filter means having different center frequencies, a switching means for switching the center frequency according to the engine speed, and a means for controlling the ignition timing of the engine according to the output of the filter means. The ignition timing control device is out.

In this way, by switching the center frequency of the filter means in accordance with the engine speed, mechanical vibrations other than knocking are no longer detected as knocking frequencies, and accurate knocking control can be performed.

(Embodiment) An ignition timing control device for an internal combustion engine according to a first embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 11 is an acceleration pickup (knock sensor) that is attached to the engine and detects vibration acceleration of the engine; 12 is an amplifier that amplifies the output signal of the acceleration pickup 11;
3 is a frequency filter that passes frequency components that are highly sensitive to knocking in the output signal of the amplifier 12, and has two center frequencies f01 and f0 as shown in FIG.
2 frequency signal is passed. Further, 14 is a filter frequency changeover switch for changing over the center frequency f01 of the frequency filter 13, and this changeover is performed by an FCU (electronic control unit) to be described later. This switching of the center frequency is performed by changing the resistance value forming a part of the frequency filter 13. Further, 15 is an analog gate that blocks various noises that interfere with knock detection from the output signal of the frequency filter 13, 16 is a noise level detector that detects the mechanical vibration noise level of the engine, and 17 is an analog gate 15. 18 is an integrator that integrates the output pulse of the comparator 17 and generates an integrated voltage according to the knocking intensity. , 19 is an electronic control unit (ECU) that changes the ignition signal to the ignition system 20 according to the output voltage of the integrator 1B.

Next, the operation of the first embodiment configured as described above will be explained. After the engine vibration acceleration signal detected by the acceleration pickup 11 is amplified by the amplifier 12, the frequency filter 13 passes only the frequency components that are highly sensitive to knocking. This is done by switching the center frequencies f01 and f02 of the frequency filter 13 in accordance with the engine rotational speed, as shown in FIG. By switching the center frequency in this way, the third
As shown by diagonal lines A and B in the figure, frequencies where noise is easily detected are avoided. The analog gate 15 blocks out various types of noise that may interfere with knock detection in the output signal of the frequency filter 13 . Then, the mechanical vibration noise level of the engine is detected by the noise level detector 16, and this noise level and the analog gate 15
The output voltages of the two are compared in a comparator 17, and a knock detection pulse is generated. Then, the knock detection pulse is integrated by an integrator 18, and an integrated voltage corresponding to the knocking intensity is generated. Then, the ignition signal to the ignition system 20 is transmitted to the electronic control unit (ECU) according to the output voltage of the integrator 18.
) and is controlled to prevent knocking.

In this way, in the first embodiment, the frequency filter 23
The center frequency of the knocking signal is changed in accordance with the engine rotation speed to prevent the knocking signal from being captured as a signal other than knocking, and to accurately grasp the knocking signal.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 2, the same parts as in FIG. 1 are given the same numbers. In this second embodiment, frequency filters 13a and 13b having different center frequencies (fol and f02) are provided as frequency filters, and first and second amplifiers 12a and 13a are provided at the front stage thereof,
The switching is performed by the output signal switching device 21 of the first or second frequency filter 13a, 13b.

In this embodiment as well, the ECU 19 switches according to the engine speed as shown in FIG. This embodiment is used when the range of change in filter frequency is larger than that of the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIG. This third embodiment is similar to the first embodiment or the second embodiment.
In the embodiment, this is used when the output of the noise level detector 16 changes significantly.

In FIG. 7, the same parts as in FIG. 1 or 2 are given the same numbers. In this third embodiment, two systems from the amplifier 12 to the integrator 1 of the first embodiment are provided, and the first
The output of the first integrator 18a or the second integrator 18b is switched by a switch 31. Further, this switching is performed by the ECU 19, and as in the first embodiment, signals other than knocking are prevented from being captured as a knocking signal, so that the knocking signal can be accurately grasped.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In this fourth embodiment, the third embodiment (seventh embodiment)
The difference is that the processing of the switch 31 shown in FIG.

Next, a fifth embodiment of the present invention will be described with reference to FIG. 9. In this fifth embodiment, the third embodiment (seventh embodiment)
The difference is that an analog OR circuit 32 performs the processing of the switch 31 in FIG.

Since the fourth to sixth embodiments described below are modifications of the third embodiment, only the different points will be described, and since the operations are the same, the explanation will be omitted.

Next, a sixth embodiment of the present invention will be described with reference to FIG. The sixth embodiment differs from the third embodiment (FIG. 7) in that the processing of the switch 31 is performed by a logical OR in the ECU 19.

In addition, in the first to sixth embodiments described above, the center frequency f01. f02, but as shown in FIG. 6, the center frequencies f01. f02
．． Knocking may be detected as three or more f03.

[Effects of the Invention] As detailed above, according to the present invention, by utilizing the fact that there are a plurality of frequencies specific to knocking caused by one knock sensor (acceleration increase), the output of one knock sensor can be adjusted to a plurality of frequencies. Since knocking is detected by switching to the ignition timing control device, it is possible to provide an ignition timing control device for an internal combustion engine that is inexpensive and can accurately control knocking.

[Brief explanation of the drawing]

1 and 2, and FIGS. 7 to 10 are block diagrams showing ignition timing control devices for internal combustion engines according to first to sixth embodiments of the present invention, respectively, and FIGS. 3 to 5 show frequency - Diagram showing engine rotational speed characteristics, Figure 6 is frequency -
FIG. 3 is a diagram showing knock sensor signal characteristics. 11... Acceleration pickup, 13... Frequency filter, 14... Filter frequency changeover switch, 15
...Analog gate, 16...Noise level detector, 17...Comparator, 18...Integrator, 19...E
C.U. 20...Ignition system. Applicant's representative Patent attorney Takehiko Suzue Frequency (kHz) Figure 3 Frequency (kHz) Figure 4

Claims (1)

[Claims] One acceleration sensor that detects vibration acceleration of an internal combustion engine, and removes noise signal components from the output of this acceleration sensor,
a plurality of filter means having different center frequencies for sorting out knocking signal components; a switching means for switching the center frequency according to the engine speed; and a means for controlling the ignition timing of the engine according to the output of the filter means. An ignition timing control device for an internal combustion engine.