JPS63139220A - Knocking detector - Google Patents

Abstract

PURPOSE:To eliminate detection leakage due to the irregularity of sensitivity caused by a vibration sensor and to enhance the control accuracy of an engine, by relaxing the evaluation of a knocking signal by minimizing the excessive control of spark advance control. CONSTITUTION:A vibration detection part 2 outputs the vibration signal corresponding to the vibration of an engine 1 and a noise detection part 5 detects the background noise vibration contained in the vibration signal to output a background noise signal. A judge part 6 judges knocking when the vibration signal becomes large on the basis of the judge reference signal determined based on the background noise signal to output a judge signal. A control signal output part 14 is constituted of a monostable multivibrator 11 turned ON over a predetermined time when the judge signal is inputted, an integration circuit 12 integrating the output value within a time and a monostable multivibrator 13 shortening the previously predetermined time to suppress the integral value. A signal output part 14 outputs a control signal reducing the control quantity of the engine due to the other judge signal generated within the predetermined time from the point of time when the judge signal is outputted.

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 when knocking is immediately determined, the evaluation of the knocking signal is relaxed, thereby preventing consecutive false detections. The present invention relates to a knocking detection device that improves the accuracy of engine control without eliminating 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 the engine 1, and a vibration detection section 2 that outputs a vibration signal according to the vibration of the engine 1, and a background noise level ( A noise detection unit 5 outputs a signal (hereinafter referred to as BGL), a determination unit 6 inputs the vibration signal and the BGL signal to determine engine knocking, and predetermines the engine ignition timing when knocking is determined. and an advance angle control section 10 that delays the angle by an angle.

The vibration detection section 2 includes a vibration sensor 3 attached to the wall surface of the engine 1, and an amplifier 4 that amplifies the signal of the vibration sensor 3 to an appropriate level (a band that passes knocking signals in a frequency band of 6 to 9 kHz). The determining 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. comparator 7, and an integrator (
For example, the integral value is reset at each ignition timing) 8,
The second comparator 9 determines that knocking occurs when the integrated value exceeds a predetermined value due to continuous output of the comparison signal for a certain period.

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 the engine 1 determines that knocking is occurring, the ignition timing of the engine 1 is delayed to suppress the occurrence of knocking.

As shown in FIG. 2, the level of the BGL signal increases depending on the engine rotation speed (RPM).

Also, knocking signals A, , A2 . Bl, Bz.

and noise signals A, , B, at high speed (Figure 3 (b))
and at low speed (FIG. 3(a)), it changes depending on the vehicle speed. 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 cylinder where knocking occurs may differ depending on the engine, and as shown in Figure 4, the cylinder where knocking occurs may vary depending on the engine.
Even if the signal level is the same, vibration sensors have high detection sensitivity (A) and low detection sensitivity (0). Therefore, B
Judging by the judgment reference signal based on the GL signal, if the judgment reference signal is set as B+ ([+), knocking cannot be detected, and S! If the judgment reference signal was set as shown in (a), noise would be detected as shown in (a), 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 to detect knocking and improve the accuracy of engine control. Reduce the engine control amount based on the knocking detected in the engine.

In other words, in knocking control, the torque is controlled to be around trace knock and light knock, which has a small decrease in torque and a low knock strength and knock consistency, and these trace knocks and light knocks rarely occur consecutively, and only a few They occur at intervals on the order of 10 seconds to seconds. When attempting to control such knock levels, it is not necessary to sensitively and sensitively detect each ignition, but rather the engine,
In order to compensate for sensitivity variations caused by the vibration sensor, knocking is determined by lowering the determination reference signal to minimize the effect of over-controlling the advance angle in the case of successive determinations, which are very rare. In order to keep the engine control level to a minimum, once a judgment is made, the engine control amount based on this judgment is reduced for a predetermined period of time, thereby preventing detection failures due to variations in sensitivity caused by the engine and vibration sensor, and improving the accuracy of engine control. The present invention provides an improved knocking detection device.

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

FIG. 5 (<) and (0) show an embodiment of the present invention, and the same parts as in FIG. A control signal output section 14 for controlling the engine is provided.

For example, the output section 14 has a monostable multivibrator 11 that is turned on for a predetermined time when the judgment signal from the judgment section 6 is input, and that is shortened by the output of a monostable multivibrator 13, which will be described later. The monostable multivibrator 13 is turned on by the output of the break 11 for a predetermined period of time, for example, slightly shorter than the above-mentioned interval of occurrence of the breaking, and the monostable multivibrator 11 normally integrates in the negative direction. It has an integrating circuit 12 that integrates in the positive direction when outputted.

As shown in (D), the monostable multivibrator 11 has two input terminals that receive the outputs of the determination unit 6 and the monostable multivibrator 13, and one terminal that outputs the output to the monostable multivibrator 13 and the integrating circuit 12. Then, when the monostable multivibrator 13 outputs, the transistor T
, is turned on, the terminal voltage of the capacitor C3 becomes smaller, so that the output pulse width becomes smaller.

With the above configuration, the operation will be explained with reference to (a) to (d) in FIG. Integrating circuit 1 outputs the time of
2 integrates the value (II). At the same time, since the monostable multivibrator 13 is turned on for a predetermined time (d), the transistor T of the monostable multivibrator 11 is turned on, so that the output pulse width of the monostable multivibrator 11 becomes shorter. Therefore, the noise signal B1゜B2
Even if (<) is 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 and becomes like the characteristic curve Y (c). become. Therefore, the average value M is not much different from the average value N of the characteristic curve N0T) when the signals B, B2 are not detected. However, if the monostable multivibrator 13 is omitted, it becomes as shown in (0). (the integral value shown by the characteristic curve X is obtained, which is much larger than its average value or value). Since the ignition timing of the engine 1 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 can be mistaken for knocking.

As explained above, according to the knocking detection device according to the present invention, by minimizing excessive control of the 7-advanced angle control and relaxing the evaluation of the knocking signal, it is possible to eliminate detection failures due to variations in sensitivity caused by vibration sensors. , it is possible to increase the appropriate pressure for engine control.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing a conventional knocking detection device, Figure 2 is an explanatory diagram showing a conventional knocking detection device.
The figure is an explanatory diagram showing the relationship between engine speed and BGL signal. Figures 3 (a) and (1) are explanatory diagrams showing vibration signals at low speed and high speed, respectively. Figure 4 (a) and ([1] are explanatory diagrams showing vibration signals from low-sensitivity and high-sensitivity vibration sensors, respectively. FIG. 5(A) is an explanatory diagram showing the first embodiment of the present invention, and FIG. 5(D) is an explanatory diagram showing the time limit circuit of (A). ) is an explanatory diagram showing the operation of Fig. 5. Explanation of symbols...Engine 2...Vibration detection section 3...
・Vibration sensor 4...Amplifier 5...Noise detection section 6...Judgment section 7.9...Comparator
...Integrator circuit 11, 13...Monostable multi-bi break 12...Integrator circuit 14...Control l signal output section Fig. 1 Fig. 2 PM C Ino No. (Inno 3 Fig. C port) 4 Fig. C Lono Figure 6 C Lono cl ~ No C Nino Procedural Amendment (Method) % Formula % 1, Indication of the case 1986 Patent Application No. 296162 2, Title of the invention Knocking Detection Device 3, Person making the amendment Case Relationship with Patent Applicant Name: Nissan Motor Co., Ltd. 4, Agent (102) 7. Amend the title of the invention column in the statement of contents of the amendment to 1. Knocking detection device.

Claims (1)

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