JPS6360846B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a knocking detector that detects knocking in an internal combustion engine using vibration.

Conventionally, it is known that knocking in an internal combustion engine can be detected from engine vibration. This utilizes the fact that when knocking occurs, pressure vibrations in the combustion chamber cause mechanical vibrations in various parts of the engine. Pressure vibrations caused by knocking in ordinary automobile internal combustion engines fall within the range of 5 to 15 KHz, and exhibit a certain value for each model of internal combustion engine.
Therefore, knocking can be detected by detecting this vibration with a vibration detector. However, the internal combustion engine body has vibration elements due to combustion and movement of various parts, and to detect vibrations caused by knocking, a detector that resonates with the vibration frequency band of knocking, as shown in FIG. 1, has been used. This has a casing 1 attached to the internal combustion engine main body, an inertial mass body 2 and a spring 3 housed in the casing, and the resonance frequency determined by the spring constant and the mass of the inertial mass body is the internal combustion engine. The frequency was chosen to be approximately equal to the frequency of the vibrations caused by the knocking of the inertial mass body, and the configuration included a conversion element 4 that converts the vibrations of the inertial mass body into electrical signals and detects them. According to this method, frequency selectivity was poor, and vibrations other than knocking were detected in some cases, making it an incomplete knocking detector. In consideration of the above points, the present invention uses two or more resonators to detect vibrations, prevents malfunctions due to vibrations other than knocking, and aims to reliably detect knocking vibrations of an internal combustion engine. Here, the reason why vibrations are detected using two or more resonators, which is an object of the present invention, will be explained using FIG. 2.

FIG. 2 is a diagram in which the number of resonators is used as a parameter, the vertical axis represents the attenuation amount representing frequency selectivity, and the horizontal axis represents the normalized frequency. The normalized frequency on the horizontal axis is the frequency of the 3 dB attenuation point, which is approximately 71% of the maximum detection level of the detector, and the upper and lower cut-off frequencies _-c and _+c of the center frequency, and the passband width Δ( =
_+c − _-c ). This horizontal axis is set by the following formula using the frequency before standardization, the center frequency ₀ , and the passband width Δ.

- ₀ /Δ/2 Therefore, this horizontal axis represents how far away the point is from the half of the 3 dB bandwidth, which is standardized as 1. Therefore, if we look at Figure 2, the resonator x has a frequency ±6 points away from the center frequency (0 position on the horizontal axis).
Compared to the fact that only about 15 dB of attenuation can be obtained, the two-resonator y provides about 28 dB of attenuation, and the three-resonator z provides about 35 dB of attenuation. This fact is made clear in general filter theory literature. Therefore, with the above-mentioned conventional structure, only a knocking detector using one resonator could be obtained, and it was incomplete as a knocking detector. The present invention aims to reliably detect target knocking vibration using two or more resonators.

The present invention will be explained below with reference to embodiments shown in the drawings.

FIG. 3 is a perspective view of essential parts of an embodiment of the present invention, in which 5a and 5b are the leads of the tuning fork, and 5e is the base of the tuning fork, which are constructed by welding, silver brazing, etc. 5c, 5
d and 5f also have the same configuration as above. These form a U-shaped tuning fork, but a U-shaped tuning fork is also possible. These tuning forks include 6a, 6c, 6d (6b
(not shown in the figure) may be added by welding, etc. The tuning forks are connected by welding or the like using connecting members 7a and 7b, respectively. 8a and 8b are piezoelectric transducers, which are attached by adhesive or the like. FIG. 4 is a perspective view of a main part of another embodiment of the present invention, in which 9a and 9b are acoustic unit deflection resonators, which are connected by soldering or the like by connecting members 10a and 10b. 11a and 11b are supporting members. FIG. 5 is a perspective view of a main part of another embodiment of the present invention, in which 12a and 12b are disk deflection resonators;
3 is a connecting member. In both cases, only two resonators are shown, but it is obvious that three or more resonators can be constructed by simply connecting similar resonators. FIGS. 6, 7, and 8 are diagrams showing examples in which the tuning fork described in FIG. 3 is mounted.

FIGS. 6 and 7 are diagrams showing the case where a tuning fork using a piezoelectric transducer is installed perpendicularly and parallel to the vibration direction of 50, respectively. Fig. 6a is a sectional view of the front, Fig. 6b is a sectional view of the side, Fig. 7a is a sectional view of the front when the tuning fork is installed in a direction different from that shown in Fig. 6; FIG. 7b is a side sectional view as well. Lead wires 15a and 15b connect piezoelectric transducers 8a and 8b to 16a and 1.
It is electrically connected to a terminal 6b. FIG. 8 is a diagram showing electromagnetic detection using a tuning fork. FIG. 8a is a front sectional view, and FIG. 8b is a side sectional view. Near the tip of the tuning fork reed are a magnetic core numbered 18, a magnet numbered 17, and a coil numbered 19. As with the piezoelectric type, the direction of the tuning fork may be perpendicular. The tuning fork is fixed to the lid 14 in each of Figures 6 to 8 by welding or the like. Of the bases 5e and 5f of the tuning fork, 5e is supported and fixed to the lid 14, so it is large, and the others are small like 5f. Depending on the shape of the lid, it is possible to have a base of the same size, but this is omitted here because it is easy to consider. Further, in both cases, the resonator is installed and fixed on the lid, but a case where the resonator is installed and fixed on the housing 1 is also conceivable. Fig. 9 is a diagram constructed using the sound piece deflection resonator shown in Fig. 4, where a is a front sectional view and b is a side sectional view, showing the case where a piezoelectric transducer is used. . The sound piece deflection resonator is a support member 11
A and 11b are installed and fixed to the lid 14 by welding or the like, and lead wires 15 are connected from the transducers 8a and 8b.
A and 15b are connected to terminals 16a and 16b. FIG. 10 is a diagram showing an electromagnetic type using a sound piece deflection resonator similar to FIG. 9. The sound piece deflection resonators are support members 11a and 11b.
It is installed and fixed on the lid 14 at. This is for supporting and fixing the sound piece deflection resonator 9b in FIG. 4, and the sound piece deflection resonator 9a is further supported by a coupling member 10b for connecting vibrations. Assuming that the resonator closest to the side that is generally supported and fixed from Fig. 6 to Fig. 12 is the input side, and conversely the resonator farthest away is the output side, 9a is the sound piece deflection resonance on the output side. He is becoming a child. Therefore, a magnet 17 and a magnetic core 18 and a magnetic core 19 are placed near the center of the output side sound piece deflection resonator 9a in the length direction, as in the case of the tuning fork in FIG.
The coils are connected to the terminals 16a and 16b by lead wires 20a and 20b. 1st
Figure 1 shows an embodiment of the present invention showing the case of a piezoelectric disc flexural resonator.
A disc deflection resonator b is supported and fixed. 13
The output-side disk deflection resonator 12a is supported by the coupling member 12a.The input and output disk deflection resonators may have additional masses 21a and 21b. A piezoelectric transducer 22 is glued to the output-side disk deflection resonator, and 23
The configuration is such that a lead wire a is used to connect to a terminal 16, and the other end is connected from the housing 1 to a terminal 16b using a lead wire 23b. FIG. 12 shows the case of an electromagnetic type, which also uses a disk resonator. Like the others, it has magnets, magnetic cores, and coils installed. In the cases of FIGS. 11 and 12, the fixing portion of the disc resonator may also be a lid 14 on the opposite side of the housing 1.

Next, to describe the operation of the above configuration, as shown in FIG. 6, the housing 1 is attached to the engine body (not shown) by the threaded part 1b of the housing 1.
, and the lid 14 also vibrates as one.
The signal is transmitted to the tuning fork base 5e. By the way, since the resonant frequency of this tuning fork is selected to be approximately equal to the frequency of vibration caused by this notching, the entire tuning fork causes vibration,
A strain is applied to the piezoelectric transducers 8a and 8b. Therefore, a voltage is generated in the piezoelectric transducer, and this output voltage is obtained from the terminals 16a and 16b, so that knocking can be detected. The embodiment shown in FIG. 7 operates in the same way as the embodiment shown in FIG. 6, and its explanation will be omitted. The operation shown in FIG. 8 is similar, except that the mechanical-to-electrical conversion transducer is of an electromagnetic type. The operation is the same until the vibration is transmitted to the output tuning fork. This tuning fork resonator is selected to be approximately equal to the vibration frequency during knocking, and the tuning fork on the output side causes resonance at that frequency during knocking, changing the gap between the magnet and the tuning fork lead. Therefore, the flux of the magnetic circuit composed of the magnet and the magnetic core changes, and a voltage is generated in the coil according to the law of electromagnetic induction. This is led to the terminals 16a and 16b, and knocking can be detected. Here, in order to improve magnetic permeability in the flux loop, it is also possible to use a magnetic core or an inner case made of another magnetic material. Figure 9 shows the case of a vibrating unit resonator, and since the vibrating unit deflection resonator is similarly selected to be approximately equal to the vibration frequency of notching, the vibration is transmitted to the input side unit deflecting resonator 9b during notching, causing resonance. (Deflection resonance occurs). This is because vibrations are transmitted to the output-side sound piece deflection resonator 9a by torsional vibration at the coupling members 10a and 10b, causing deflection resonance. Therefore, distortion is applied to the piezoelectric transducers 8a and 8b, and a voltage is generated. This output voltage is obtained from the terminals 16a and 16b, and knocking can be detected. FIG. 10 operates similarly to the embodiment of FIG. 9, except that the mechanical-to-electrical conversion transducer is of the electromagnetic type. The operation is the same until the vibration is transmitted to the output sound piece deflection resonator 9a. This sound piece deflection resonator 9
a and 9b are selected to be substantially equal to the vibration frequency during knocking, and the output-side sound piece deflection resonator changes the gap between the magnet and the sound piece deflection resonator during knocking. For this reason, the flux of the magnetic circuit made up of the magnet and magnetic core changes, and a voltage is generated in the coil according to the law of electromagnetic induction. This is guided to terminals 16a and 16b, and knocking can be detected. Here again, as mentioned above, it is conceivable to use a magnetic core or an inner case made of a magnetic material in order to improve the magnetic permeability in the flux loop.
Figure 11 shows the case of a disc flexural resonator, and since the disc flexural resonator is similarly selected to be approximately equal to the knocking vibration frequency, the vibration is transmitted to the input side disc flexural resonator 12b during knocking, causing resonance. The longitudinal vibration is coupled by a coupling member 13, causing deflection resonance in the output side disc resonator 12a. On the other hand, a piezoelectric transducer 22 is soldered to the disc resonator 12a on the output side. For this reason, the piezoelectric transducer 22 causes deflection resonance together with the output-side disc deflection resonator 12a, which applies distortion to the transducer and generates a voltage, and this output voltage is passed through the lead wires 23a and 23b to the terminals. 16a and 16b, and knocking can be detected. FIG. 12 operates similarly to the embodiment of FIG. 11, except that the mechanical-to-electrical conversion transducer is of the electromagnetic type. As for the operation, the vibration is the 11th one up to the output side disc deflection resonator 12a.
This is the same as the case shown in the figure. This disk deflection resonator 1
2a and 12b are disk deflection resonators 12a on the output side whose vibration frequencies at the time of knocking are selected to be approximately equal.
changes the gap between the magnet and the disc flexural resonator during knocking. For this reason, the flux of the magnetic circuit made up of the magnet and magnetic core changes, and a voltage is generated in the coil according to the law of electromagnetic induction. This is terminal 16a, 1
6b, knocking can be detected. In this case, as described above, it is also conceivable to use a magnetic core or an inner case made of another magnetic material in order to improve the magnetic permeability in the flux loop. The above figure shows only an example of two resonators, but by connecting one or more resonators between the input side resonator and the output side resonator via a coupling member, three or more resonators can be connected. A configuration of the resonator is also conceivable.

Since the knocking detector according to the present invention uses two or more resonators to detect vibrations, it has the effect of preventing malfunctions due to vibrations other than knocking vibrations, and can reliably detect knocking vibrations.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional knocking detector. FIG. 2 is a diagram for explaining that two or more resonators of the present invention have excellent selection characteristics. FIG. 3 is a perspective view of essential parts of an embodiment of the present invention. FIG. 4 is a perspective view of essential parts of another embodiment of the present invention. FIG. 5 is a perspective view of essential parts of another embodiment of the present invention. FIG. 6a shows the first embodiment of the present invention.
FIG. 6b is a front view (sectional view) of the embodiment, and FIG. 6b is a side view (sectional view) of the second embodiment of the present invention. Figure 7a
are a front view (sectional view) of the second embodiment of the present invention;
Figure b is also a side view (sectional view). FIG. 8a is a front view (sectional view) of the third embodiment of the present invention, and FIG. 8b is a side view (sectional view) of the same. FIG. 9a is a front view (cross-sectional view) of the fourth embodiment of the present invention, and FIG. 9b is a side view (cross-sectional view) of the same. FIG. 10a is a front view (cross-sectional view) of the fifth embodiment of the present invention, and FIG. 10b is a side view (cross-sectional view) of the same. FIG. 11 is a sectional view of a sixth embodiment of the present invention. FIG. 12 is a sectional view of a seventh embodiment of the present invention. 1... Housing, 5a, 5b, 5c, 5d... Tuning fork lead, 5e, 5f... Tuning fork base, 6a, 6c, 6
d, 21a, 21b...additional mass, 7a, 7b, 1
0a, 10b, 13... coupling member, 8a, 8b, 2
2... Piezoelectric transducer, 9a, 9b... Sound bar resonator, 11a, 11b... Support member, 12a, 12
b... Disc resonator, 14... Housing lid, 15a, 15
b, 20a, 20b, 23a, 23b...Lead wire, 16a, 16b...Terminal, 17...Magnet, 18...
Magnetic core, 19...coil.

Claims (1)

[Claims] 1. A knocking detector for an internal combustion engine characterized by detecting vibration by coupling two or more resonators with a coupling member.