JPS5880539A - Detection for knocking of internal combustion engine - Google Patents

Abstract

PURPOSE:To detect generation of knocking correctly and accurately and to control knocking with high accuracy by mounting an oscillation detecting element which converts mechanical oscillations to amplitude fluctuations of electric signals to a machine body. CONSTITUTION:A knocking sensor 12 is constituted of, for example, a piezoelectric element or an electromagnetic element and is designed to convert mechanical oscillations to electrical amplitude fluctuations. Crank angle sensors 16 and 18 are provided to a distributor 14. The electric signals from the sensor 12, and the sensors 16 and 18 are fed to a control circuit 20. The magnitude between the differentiated value of the DC voltage changing according to the amplitude of the output of the knocking sensor in a prescribed crank angle range and the 1st comparing reference value is compared and the magnitude of the knocking is compared. Thus not only the presence or absence of the generation of the knocking but also the degree thereof are detected accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting whether knocking occurs in an internal combustion engine and the magnitude of the knocking that occurs.

The knocking detection force method detects mechanical vibrations caused by abnormal engine combustion, that is, knocking, as electrical amplitude fluctuations using a vibration detection element called a knock sensor. The present applicant has already proposed a method for detecting the occurrence of knocking depending on whether the differential value of envelope deflection exceeds a predetermined value.

Bao +) In! It is possible to determine whether the vibration detected by the knock sensor is due to knocking or mere noise such as pulp hammering sound by knowing the echo value of . However, since the differential value of the envelope edge does not change depending on the degree of knocking, it is impossible to detect the magnitude of knocking based on this. If the degree of knocking cannot be grasped, the value of 1'l1IJ when performing knock suppression'+ttlJ control cannot be determined, leading to excessive or insufficient control.

Therefore, the present invention solves the above-mentioned problem.
An object of the present invention is to provide a knocking detection method that can accurately detect not only whether knocking has occurred but also the degree of knocking that has occurred.

The features of the present invention that achieve the above-mentioned objects are as follows:
- At least one vibration detection element is mounted on the machine body to convert the amplitude fluctuation of the electric signal into an amplitude fluctuation of the electric signal, and the vibration detecting element changes according to the amplitude of the electric signal in a predetermined crank angle range after the ignition of at least one predetermined cylinder. The presence or absence of knocking is detected by comparing the differential value of the DC voltage with a first comparison reference value, and the maximum amplitude of the electric signal in the crank angle range is compared with a second comparison reference voltage. The purpose is to detect the magnitude of knocking by comparing the magnitude of.

The present invention will be described in detail below using the drawings.

FIG. 1 schematically shows the overall configuration of an embodiment of the present invention. In the figure, reference numeral 10 denotes a knock sensor attached to the cylinder block of the engine, 12Fi cylinder block lOK. The knock sensor 12 is a well-known device that is composed of, for example, a piezoelectric element or an electric aperture, and converts mechanical vibrations into electrical amplitude fluctuations. In FIG. 1, 14 further indicates a distributor, and slots 16 and 18 are provided. The crank angle sensor 16G''i is for cylinder discrimination, and if this engine has 6 cylinders, it will generate 1 rotation every time the distributor shaft rotates once, that is, every 21g rotation of the crankshaft (every 72°UA).
Generates two pulses. The location of its occurrence is nine examples:
It is set like the top dead center of a cylinder. Crank angle sensor 18
generates 24 pulses each time the ristriviator shaft rotates once, and thus generates pulses with a crank angle of 3σ.

The air pressure signals from the knock sensor 12 and the crank angle sensors 16 and 18 are sent to the control circuit 20. 1ti
The lJ-circuit 20 is further supplied with a signal representing 1r for the intake air flow from an air flow sensor 24 provided in the intake passage 22 of the engine. On the other hand, the control circuit 20 is unable to output the ignition signal to the igniter 26, and the igniter 2
6 is distributed to the ignition knock 28 of the valley cylinder via the distributor 14.

The engine is provided with various other sensors for detecting abuse and operating condition parameters, and the control circuit 20 includes:
The fIIIJ control of the fuel injection valve 29 and the like is also performed, and since these are not directly related to the present invention, all of these will be omitted in the following explanation.

FIG. 2 is a block diagram showing an example of the structure of the control circuit 20 shown in FIG. The voltage signal from the airflow sensor 24 is sent to the analog multiplexer 3 via a buffer 30i.
The signal is sent to the microcomputer 2, selected according to instructions from the A/L) converter 34, and converted into a binary signal. It is captured.

/ for every 720° crank angle from the crank angle sensor 16
The four pulses are applied to the interrupt request signal forming circuit 40 via the buffer 38. On the other hand, i'? pulses for every 30'' crank angle from the crank angle sensor 18 are applied to the interrupt** signal forming circuit 40 and the speed signal forming circuit 44 via the buffer 42.The interrupt request signal forming circuit 40 teeth,
From each Norms for every 720" crank angle and every 3σ, -
A pre-loaded Hosui signal is formed. These interrupt request signals are applied to the microcomputer via the input/output port 46. The speed 1 formation cycle 1Nr44 is the engine rotational speed N6 from the period of 7 russ per 30" crank angle.
A binary signal representing 1 is formed.

The formed NFC rotation speed signal is fed into the microcomputer via the input/output port 46.

Output 11 of knock sensor 12! The number is a buffer for impedance conversion and a frequency band specific to knocking (7 to 7).
8KHz) through a circuit 47 consisting of a bandpass filter whose passband is ! & flow circuit 48 and peak hold circuit 49. The rectifier circuit 48 performs full wave or hand rectification of the output signal from the knock sensor 12 that blocks the circuit 47.

The rectified signal is sent to the loaf nine filter 50, and the output of the loaf nine filter 50 is the result of envelope detection of the output signal of the knock sensor 12. This envelope signal is differentiated in a differentiating circuit 51, and the 11
It becomes a signal representing a meeting. The output of the differentiating circuit 51 is sent to a peak hold circuit 52.

Beak hold circuits 49 and 52Fi, fusing 53 and 5
4 Furthermore, each peak hold operation is performed only when a hold instruction signal is applied from the micro combinator via the input/output port 46.

That is, during this period, the peak hold circuit 49 takes in the output signal from the knock sensor 12 and holds the maximum pitch. Also, during this period, the peak hold circuit 52Fi receives the output signal of the differentiating circuit 51 and holds its maximum value. These peak hold circuits 49
The outputs of and 52 are converted into binary signals by A/D converters 55 and 56, respectively, and sent to the microcombi rotor via the input/output port 46. However, A/
l) The start of A/Di conversion of the converters 55 and 56 is performed by the A/f)&M activation signal applied from the microcombination device via the input/output ports 46 and @57 and 58, respectively. Also, when the A/D conversion is completed, the A/D
The converters 55 and 56 connect the AID to the microcomputer via the fuses 59 and 60t and the input/output port 46t.
Notify conversion completion.

On the other hand, when the microcomputer outputs an ignition signal to the drive circuit 61 through the input/output port 46, the stiffness is converted into a drive signal and the igniter 26 is energized. As a result, ignition tBIJ control is performed according to the duration and duration of the ignition signal.

The micro combinator includes the aforementioned input/output ports 36 and 46, a microprocessor (MPU) 62, a random access memory (ftAM) 64, a read-only memory (ROM) 66, a clock generation circuit (not shown), a memory control circuit, and The W4 line is mainly connected to a path 68 etc. which connects these and transfers data. The microcomputer executes the regular process according to the control zologram stored in the ROM 66.

The microcomputer detects a period during which only a knocking signal is mainly included in the signal from the knock sensor 12 (knocking detection period, for example, 10Fi, AT, in the explosion stroke of each cylinder or a predetermined specific cylinder).
A peak hold instruction signal is sent to the peak hold circuits 49 and 52 during the period from DC to 50° C. ATDC. Further, at the end of the knocking detection period, an A/D conversion start signal is given to the A/D converters 55 and 56 to cause the outputs of the peak hold circuits 49 and 52 to be A/D converted. When the A/D conversion completion notifications are applied from the A/D converters 55 and 56, the microcombination controller stores the converted binary signals in respective predetermined positions in the RAM 640. Therefore, data Vmax corresponding to the maximum width value of the output of the knock sensor 12 during the knocking detection period and data dv/ corresponding to the maximum value of the differentiated value of the envelope Mtjl of the output of the knock sensor 12 during the knocking detection period.
dtm□ will be stored in the RAM 64, respectively.

FIG. 3 is a flowchart showing the part related to the present invention in the control program of the microcombi-combi. When a predetermined interrupt request signal is applied at a position before a predetermined crank angle, for example, 90Fi, BTDC, the MPU 62 executes the interrupt processing routine shown in FIG. First, in step 70, input data relating to the rotational speed Ne and the intake air flow Q, which were taken in during other processing routines, are read from the RAM 64. Next, in Stella 7''71, the basic ignition advance angle oBAsICt according to ee and Q
Calculated using TIJ knowledge method. In the next step 72, the maximum value of the differential value of the envelope edge dv/dtmaX WrR
Read from AM64, next nos f ff 73 kc
j, ·Vh, it is determined whether this IIfdv/dtmax is equal to or greater than a smoothly determined l-th comparison reference value A. "No = f), that is, if dv/dtrnax is A, it is determined that no knocking has occurred, and the process proceeds to step f74.
Processes 77 to 77 are executed. For Sten f74 to 77, the past 101! ! If no knocking occurs during consecutive ignition cycles, the ignition timing correction amount θkt-
The purpose is to increase only α. That is, in step 74, it is determined whether or not n is 10 or more, and if it is 10 or less, n is increased by 1 at Stella f75 and then the process proceeds to Stella f7B. On the other hand, if n is 10 or more, then n is increased by 1 at Stella f75. goes to Stella "j' 76, resets it to nt-zero, and then goes to step 77. In step 77, processing is performed to increase the ignition timing advance angle correction amount Ok by α. For example, α is α
=lUl1m is selected. Next, the program is Stella f7
Proceed to step B, and add the advance angle correction sound θkK-to the basic ignition advance angle θBmsm obtained at step 71 to determine the final ignition advance angle θ.
get. That is, in Stella f7B, θ←θBA81C+#
calculation is performed, and the basic ignition advance angle θBA8]C is changed to θ by 7.
12II'f is corrected.

When the processing of Stella f7B is completed, the process returns to the main routine.

On the other hand, if it is determined in step 73 that dv/dtmax≧A, that is, if it is determined that knocking has occurred, the process proceeds to step 79 and n is reset to zero.

Next, in Stella f80, the maximum value Vmax of the amplitude of the knock sensor output is read from the RAM 64, and in the next Stella 7'81, it is determined whether this value Vmax is equal to or greater than a predetermined second comparison reference value B. Determine. @NO", that is, when Vmax<B, it is determined that the knocking is small, and in the next step 82,
The advance angle correction amount θk is decreased by β. For example, β=
In the primary stellar f7H selected at 1°C A, the basic ignition advance angle θBAEIK is corrected in the same manner as described above.

On the other hand, if -YNS'', that is, if Vmax≧B, it is determined that the knocking is strong, and the next Stella f8
In step 3, the advance angle correction amount θk is decreased by γ. ri
69 with dγ>β, for example, γ=2°C is selected. Next, in step 78, the basic ignition advance angle θBA81! Correction of i is performed. It is well known that correcting the ignition timing in an advanced direction can improve engine output, and correcting it in a retarded direction is effective in suppressing knocking.
FIG. 4 is a diagram for explaining the operation of the above-mentioned embodiment, and (4) shows the output wave of the knock sensor 12 when vibration different from knocking occurs (when noise occurs). , jL1 and its envelope waveform bt, (BJ is the output waveform J of the knock sensor 12 when relatively small knocking occurs and its envelope m waveform bs, (Q is the knock sensor when relatively large knocking occurs) 12 output waveform a
s and its envelope waveform bs t- are shown respectively. As is clear from the same figure, Noksen? The slope of the envelope line of the output of No. 12 is significantly different between vibrations caused by knocking and vibrations other than knocking. Therefore, by comparing the envelope line output t-differentiated value with a predetermined comparison reference value, it is possible to correctly determine whether or not the tracking has occurred. Then, when it is determined that knocking has occurred, what l! is the maximum value of the amplitude of the knock sensor output? ! ! If you know the degree of tsukking, you can accurately judge the degree of tsukking.

In addition, in the above-mentioned embodiment, the envelope f of the knock sensor output
However, in the present invention, it is only necessary to differentiate the DC voltage that changes depending on the amplitude of the knock sensor output.
This is, for example, the effective value of the knock sensor output, the average value after rectification, etc.

As explained in detail above, according to the present invention, knocking is detected by comparing the magnitude of the differential value of the DC voltage that changes depending on the amplitude of the knock sensor output in the Qr foot crank angle range with the comparison reference value of $1. On the other hand, since the magnitude of knocking is compared by comparing the maximum amplitude of the knock sensor output in the above crank angle range with the second comparison reference value, the presence or absence of knocking is detected. It is possible to accurately detect not only the presence or absence of knocking but also the degree of knocking that has occurred. The detection method of the present invention can be used to accurately detect knocking occurrence.
Control can be performed based on knowledge of the actual VC, and knocking suppression control can be performed in accordance with the degree of non-king. In other words, the aJ ability is achieved by controlling Kozue's extremely high knocking.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the overall configuration of the Honbatsucho Ichisho Example, Fig. 2 is a block diagram of the control circuit as shown on page 1, Fig. 3 is a 70-chart of the interrupt processing routine of the control circuit, and Fig. FIG. 4 is a waveform diagram for the effect of the present invention f: congratulations. lO... Cylinder block, 12... Knock sensor, 14... 1 Knives rivet regulator, 16.18... Crank angle sensor, 20... Control circuit, 36.46...
・Input/output/-), 47... Buffer and filter (b) path, 48... Rectifier circuit, 49.52... Peak hold circuit, 50... Low pass filter, 51...
Differential circuit, 34.55, 56...A/D conversion gain, 62
...MPU. 64...RAM, 66...ROM. Patent Applicant Toyota Motor Corporation Patent Application Agent Patent Attorney Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Akira Yamaguchi

Claims (1)

[Claims] 1. At least one vibration detection element for converting mechanical vibration into an amplitude fluctuation of an electric signal is attached to the tube machine body, and the vibration detection element converts the mechanical vibration into an amplitude fluctuation of an electric signal in a predetermined crank angle range after ignition of at least one cylinder. The presence or absence of knocking is detected by comparing the magnitude of the differential value of the DC voltage that changes accordingly with a first comparison reference value. A method for detecting knocking in an internal combustion engine characterized by detecting the magnitude of knocking by comparing the magnitude with a comparison reference value.