JPS6356487B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] In order to prevent detection failures, the present invention uses a relatively low judgment standard, and once knocking is determined, the evaluation of the knocking signal is relaxed to prevent consecutive false detections. The present invention relates to a knocking detection device that improves the accuracy of engine control without any knocking.

[Conventional technology]

As a conventional knocking detection device, for example, there is one shown in FIG. 1, which includes a vibration detection section 2 that outputs a vibration signal corresponding to the vibration of an engine 1, and a vibration detection section 2 that outputs a vibration signal corresponding to the vibration of an engine 1, and a background noise level ( a noise detection unit 5 that outputs a signal (hereinafter referred to as BGL);
It has a determining section 6 that inputs a vibration signal and a BGL signal to determine engine knocking, and an advance angle control section 10 that delays the ignition timing of the engine by a predetermined angle when knocking is determined. The vibration detection unit 2 includes a vibration sensor 3 attached to the wall surface of the engine 1, and an amplifier 4 (a band that passes the knocking signal in the frequency band of 6 to 9 KHz) that amplifies the signal of the vibration sensor 3 to an appropriate level. The determination unit 6 compares the vibration signal with a determination reference (slice level) signal corresponding to the level of the BGL signal, and outputs a comparison signal when the vibration signal is large. an integrator 8 that outputs the integral value of the comparison signal (for example, the integral value is reset at each ignition timing), and an integrator 8 that outputs the integral value of the comparison signal (for example, the integral value is reset at each ignition timing). It is comprised of a second comparator 9 that determines knocking when the value exceeds the specified value.

With the above configuration, the comparison signal output when the vibration signal corresponding to the output of the vibration sensor 3 exceeds the judgment reference signal corresponding to the level of the BGL signal is integrated, and the integral value reaches a predetermined value. When it is determined that knocking is occurring, the ignition timing of the engine 1 is delayed to suppress the occurrence of knocking.

The level of the BGL signal is as shown in Figure 2.
It increases depending on the engine rotation speed (RPM). Furthermore, the knocking signals A ₁ , A ₂ , B ₁ , B ₂ and the noise signals A _x , _B It changes accordingly. For this reason, knocking is determined based on a comparison between the vibration signal and a determination reference signal predetermined according to the vehicle speed.

However, the cylinders where knocking is more likely to occur may differ depending on the engine, and as shown in Figure 4, even if the BGL signal level is the same,
There are two types of vibration sensors: high detection sensitivity and low detection sensitivity. Therefore, when making judgments using the judgment reference signal based on the BGL signal, if the judgment reference signal is set as B ₁ , knocking cannot be detected in B, and if the judgment reference signal is set as S ₂ , knocking will be detected as in A. was detected, making it difficult to set the judgment reference signal, and there was a risk that the control of the engine's ignition timing would lack accuracy.

In view of the above, the present invention eliminates the failure to detect knocking by using a low-level judgment reference signal in order to prevent failure in detection and improve the accuracy of engine control. Reduce the engine control amount based on knocking detected within the time period.

In other words, in knocking control, the torque is controlled to be close to trace knocks and light knocks, which have a small decrease in torque, low knock strength, and low knock frequency, and these trace knocks and light knocks rarely occur consecutively, and only occur after several tens of seconds. They occur at intervals on the order of seconds. When trying to control knocking to such a level, it is not necessary to detect knocking with high sensitivity for each ignition, but rather to compensate for variations in sensitivity caused by the engine and vibration sensor, it is necessary to lower the judgment reference signal somewhat to determine knocking. In order to minimize the influence of over-controlling advance angle control in the case of successive determinations, which are very rare, once a determination is made, the engine control amount based on this determination is maintained for a predetermined period of time. By making the size of the knocking detection device small, it is possible to prevent omissions in detection due to variations in sensitivity caused by the engine and vibration sensors, and to provide a knocking detection device that improves the accuracy of engine control.

The knocking detection device of the present invention will be explained in detail below.

FIGS. 5A and 5B show an embodiment of the present invention, and the same parts as in FIG. A control signal output section 14 for controlling is provided. For example, the output unit 14 is turned on for a predetermined time when the determination signal from the determination unit 6 is input,
The monostable multivibrator 11 shortens the above-mentioned time by the output of the monostable multivibrator 13, which will be described later, and the time predetermined by the output of the monostable multivibrator 11, e.g. The monostable multivibrator 13 is turned on for a slightly short period of time.
and an integrating circuit 12 which normally integrates in the negative direction and integrates in the positive direction when the monostable multivibrator 11 outputs. As shown in FIG.
3 and one terminal that outputs to the integrating circuit 12, and when the monostable multivibrator 13 outputs, the transistor T _B turns on, so the terminal voltage of the capacitor C ₃ becomes small, and the output pulse width becomes small. have.

With the above configuration, the operation will be explained using A to D in FIG. 6. For example, when the knocking signal _A1A is detected, a judgment signal is output, and when the monostable multivibrator 11 outputs the first time, the integration circuit 12 integrates the value. At the same time, since the monostable multivibrator 13 is turned on for a predetermined period of time, the transistor T _B of the monostable multivibrator 11 is turned on, so that the output pulse width of the monostable multivibrator 11 becomes shorter. Therefore, even if the noise signals B ₁ and B ₂ are detected and the judgment signal is input to the monostable multivibrator 11, the pulse width of the monostable multivibrator 11 becomes shorter, so its integral value becomes smaller. The characteristic curve becomes like Yc. Therefore, the average value does not differ much from the average value of the characteristic curve Nc when the signals B ₁ and B ₂ are not detected (however, if the monostable multivibrator 13 is omitted, the characteristic curve becomes as shown in B). An integral value indicated by X is obtained, and its average value gradually increases). engine 1
Since the ignition timing is controlled according to the integral value, the influence of noise can be minimized.

The above embodiments are effective when there is a high probability that a knocking signal is included in noise that is confusing as knocking.

As explained above, according to the knocking detection device according to the present invention, over-controlling the advance angle control is minimized and the evaluation of the knocking signal is relaxed, thereby eliminating detection failures due to variations in sensitivity caused by the vibration sensor. It is possible to increase the accuracy of engine control.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a conventional knocking detection device, and FIG. 2 is an explanatory diagram showing the relationship between engine speed and BGL signal. FIGS. 3A and 3B are explanatory diagrams showing vibration signals at low speed and high speed, respectively. FIGS. 4A and 4B are explanatory diagrams showing vibration signals from low-sensitivity and high-sensitivity vibration sensors, respectively. FIG. 5A is an explanatory diagram showing the first embodiment of the present invention, and FIG. 5B is an explanatory diagram showing the time limit circuit of A. FIGS. 6A to 6D are explanatory diagrams showing the operation of FIG. 5. Explanation of symbols, 1...Engine, 2...Vibration detection section, 3...Vibration sensor, 4...Amplifier, 5...Noise detection section, 6...Judgment section, 7, 9...Comparator, 8
... Integrating circuit, 11, 13... Monostable multivibrator, 12... Integrating circuit, 14... Control signal output section.

Claims (1)

[Scope of Claims] 1. A vibration detection section that outputs a vibration signal corresponding to engine vibration; a noise detection section that detects background noise vibration included in the vibration signal and outputs a background noise signal; and the background noise signal. a determination unit that determines knocking and outputs a determination signal when the vibration signal becomes large according to a determination reference signal determined based on the determination signal; an integrating circuit that integrates the output value within the time period; and a means for shortening the predetermined time period and suppressing the integral value, the method comprising: a means for turning on the output value within the predetermined time period; and a means for reducing the predetermined time period and suppressing the integral value; A knocking detection device comprising: a control signal output section that outputs a control signal that reduces the control amount of the engine based on another determination signal generated in the knocking detection device.