JPS5828598A - Knocking detection method for internal combustion engine - Google Patents

Abstract

PURPOSE:To produce a correct background signal by comparing the signals from the vibration detecting element in the first and second crank angle ranges and deciding the knocking while varying the first range in accordance to the calculated firing timing. CONSTITUTION:MPU62 will calculate the optimal firing timing t then calculate the starting time t1 of the background detection interval while at the time t1 the integrating operation of the rectified signal from a knock sensor 12 will start to calculate such that the end of said detection interval will be immediately before the time t thus to complete the integration of the first integrating circuit 51. Then the knock detection interval t3-t4 is calculated. MPU62 will contain the A/D conversion level (b) from the first integrating circuit 51 in RAM64 during the background detection interval while contain the A/D conversion level (a) from the second integrating circuit 53 in RAM64 during the knock detection interval. Then (a) and K.b are compared to decide the existence of the knocking. Since the background detection interval range is calculated in accordance to the calculated firing timing, the inconvenient noise such as the firing noise can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting whether or not knocking occurs in an internal combustion engine.

In the knocking detection method, mechanical vibrations that occur due to abnormal combustion in an engine, that is, knocking, are detected as electrical amplitude fluctuations using a vibration detection element called a knock sensor. When compared with the comparison reference value, it is possible to determine whether the detected vibration is actually caused by knocking.In this case, without fixing the comparison base to a constant value, By changing this comparison reference value in accordance with an output signal (hereinafter referred to as a background signal) that is considered to be unrelated to knocking of the knock sensor, it becomes possible to compensate for variations in the knock sensor, changes over time, etc.

As a background signal detection power method, take out the output of the knock sensor in a crank angle range of /5 + constant,
According to the 0ζ method, which has a method of calculating the average value of the amplitude and using it as a background signal, the background signal is detected while avoiding the crank angle range St, where noise such as pulp hammering noise is likely to occur. Therefore, a background signal that is less affected by noise can be obtained, and as a result, the accuracy and reliability of knocking detection are improved.

It is an object of the present invention to further develop the above-mentioned technology to obtain a more accurate and reliable paraphrase 2nd signal, thereby further improving the accuracy and reliability of knocking detection.

The feature of the present invention that achieves this purpose is the mechanical fishing section 1I.
At least one vibration detection element that converts the amplitude fluctuation of the lvt electric signal into an amplitude fluctuation is attached to the engine body, and the ms detection element detects vibration in a predetermined range of crank angles before the top dead center of at least one cylinder. By storing the amplitude value of the electric signal and comparing the magnitude of the amplitude value of the electric signal in a predetermined 112 crank angle range after ignition of at least one cylinder with the stored value. There is a method for detecting the presence or absence of knocking, which comprises calculating the ignition timing of the predetermined critical cylinder, and changing the first crank fIIi degree range according to the calculated ignition timing. The original f
IAt - Explain in detail.

FIG. 1 schematically shows the overall structure of one embodiment of the present invention. In the figure, 1o is a cylinder block of the engine, and 12d is a knock sensor attached to the cylinder block 10. The knock sensor 12 is a well-known device that is composed of, for example, a piezoelectric element or an electric element, and converts mechanical vibrations into electrical amplitude fluctuations. In FIG. 1, 14 further indicates a distribution island, and this distribution island 14 has a crank angle sensor 1.
6 and 18 are provided. The crank angle sensor 16 is for cylinder discrimination. If this machine has 6 cylinders, the crank angle sensor 16 is used for cylinder discrimination, and if this machine has 6 cylinders, the crank angle sensor 16 generates a The crank angle sensor 18 generates 24 pulses and its generation position is set, for example, at the top dead center of the wL1 cylinder. Generates a pulse every °.

Electrical signals from knock sensor 12 and crank angle sensors 16 and 18 are fed into control @ approximately 20. The control circuit 20 is further fed with a signal representing the intake air flow rate from a nine air flow sensor 24 provided in the intake passage 12 of the engine. On the other hand, an ignition signal is output from the control path 20 to the igniter 26, and the spark current generated by the igniter 26 is distributed to the spark plugs 28 of each cylinder via the distributor 14. for,
Normally, various other sensors are provided to detect operating status parameters, and control @112G controls 29% of the conventional injection valve, but these are not directly related to the main engine. Rounding, in the following discussion, all of these will be omitted.
The voltage signal is sent to the analog multiplier t32 via the parallel handle 301, and is selected from the input microcombination system according to the O instruction and applied to the 4/D* converter 9134.
After being converted into a signal, it is input into the microcomputer via the input/output port 36 for one day.

Pulses at every 720° crank angle from the crank angle sensor 16 are applied to an interrupt request signal forming circuit 40 via a buffer 38. On the other hand, pulses from the crank angle sensor 18 every 30 degrees of crank angle are sent to the interrupt request signal forming circuit @40 and the speed signal forming circuit 44 via the buffer 42.
is applied to

The interrupt request signal forming circuit @40 forms various interrupt request signals from each pulse every 720Q and every 300 crank angles. These interrupt request signals are sent to the input/output port 46.
The 0-speed signal is applied to the microphone through the combi island-evening circuit 44, which is formed to form a 2-over signal representing the engine rotational speed N@ from the period of the crank angle 3 G' every O pulse. The rotational speed signal is sent to the four-microphone combination speaker via the input/output port 46.

The output signal of the knock sensor 12 has a buffer for impedance conversion and a frequency band (7 to 81
Gi, ) is sent to the rectifier R circuit 50 through a circuit wi4g consisting of a bandpass filter serving as a passband, and is subjected to full-wave rectification or hand-to-hand rectification. Rectified signal Fi
Integration times of @1 $151 and 11 with different time constants
In other words, the first integrating circuit 51 has a relatively large time constant, and its output is a voltage value obtained by averaging the amplitude of the output signal of the knock sensor 12. To have. The 112 integration times $353 have a relatively small time constant, and the output corresponds to the maximum amplitude of the output signal of the knock sensor 12, that is, the envelope, and has a voltage value of 9.

The integration circuit $i51 of this IIEI is configured to perform integration only at 9 o'clock by applying the integration instruction bias of the logic 111 from the microcomputer via the line 51st to the integration circuit 53 of stage 112 via $152. 01
The single power of the 11 integral circuit s1 and the @2 integral circuit 53 is converted into a 2-pass signal by the converter 54, and sent to the micro combinator via the input/output port 46.
Dangerous, the false conversion start of the scoop converter 54 is caused by the input/output port 4
This is performed by a +D conversion start signal applied from the microconbeater via 6 and 1lt56t-. -! Moreover, when the false conversion is completed, the scoop converter 54 converts 1M! 58 and the input/output port 46t, a fake conversion completion notification is sent to the micro combinator.

On the other hand, when an ignition signal is output from the microcombi to the drive circuit 60 via the input/output boat 46, this is converted into a drive signal to energize the igniter 26, and the duration and duration of the ignition signal are determined. Ignition control is performed according to the timing.

The micro combinator includes the aforementioned input/output boards 36 and 46, a microprocessor (MPU") 62, a random access memory (RAM) 64, a read-only memory (ROM) 66, a clock generation circuit (not shown), a memory control circuit, and It mainly consists of the paths 68 connecting these pipes, etc., and executes various processes according to the control program stored in the p%ROM 66P3. According to the processing routines shown in Figs. 3 to 6, the signal from the knock sensor 12 does not contain any mechanical vibration noise such as knocking sound or pulp knocking sound. , the integral operation of the *R* signal of the knock sensor output is performed during the 9th period C (background detection period), which includes only the basic vibration of the engine, and the integral value is taken as the 2-over signal. This pack ground detection period is determined between 90' and 800' during the compression stroke of each cylinder or a predetermined specific cylinder.
According to the routine from Figure 0116 to Wa@, which is variably controlled to start from Cmu BTDC and end immediately before the ignition timing, the OS-E from the knock sensor 12 will contain a knocking signal. Estimated period (
(knocking period) K Knock sensor output 0*mm is integrated, and its final value is warmed up as a 2 over signal. The excessive signal is compared with the two excessive signals inputted by IK in the current processing routine, and it is determined whether or not young has occurred. In addition, this knocking detection period, tt, < is 10 in the explosion stroke of each cylinder or a predetermined &51# cylinder.
'CA-ATDC ~ Selected near 50° CA@ATDC.

The contents of the processing routines shown in FIGS. 3 to 8 will be explained in detail below.

The interrupt request signal forming circuit 40 outputs a position a predetermined rank angle θoCA before the compression top dead center of each cylinder or a predetermined specific cylinder, for example, 90'CA-BTDC.
When a predetermined interrupt request signal is applied in , the MPU 6
2 executes the interrupt processing routine shown in FIG. The optimal ignition time 1IAt# (time on the soft timer) is calculated using the method, and the value is stored in iAMjBc. Next, in step 71, time t1 at which the pack ground detection period starts is calculated. At this time, the side control is the time of the timer on the 77 toeware, and the crank angle displacement 1 is the time when the pack ground detection period starts.
1 (for example, current +7 at 60°CA・BTDC') / 5
It is clear that it can be easily calculated if the current time t of the timer and the rotational speed Ne of the engine are known. When the processing in step 71 is completed, the program returns to the main routine.

When the time of soft tie i reaches tl, a time interrupt request is generated, and the MPU 6z executes the interrupt processing routine shown in FIG. Action tl - Start. This is accomplished by sending an integration instruction signal of %11 level to the tenth integration circuit 51 via the line 52.

Next, in step 73, the time t at which the pack ground detection period ends is calculated according to the optimum ignition timing t#. That is, the time t! This time is is calculated based on the interval left immediately before the optimum ignition timing t-, for example, t2←t@-0,1, (see).

When the soft timer shows time t2, a 25-hour interrupt request is generated, and the MPU 62 then executes the interrupt processing routine shown in FIG. II5. First, in step 74, the integration operation of the first integration circuit 51 is terminated. This is accomplished by inverting the integration indication signal t-%0# via line 52.

Next, in step 75, the time t at which the knocking detection period starts is calculated.The crank angle position (for example, 10° CA-ATDC) at which the knocking detection period starts is predetermined, so the calculation method in step 75 is Step #1 is similar to that of step 71. The program then returns to the main routine.
+B conversion start and start 0 instructions are given at predetermined time intervals via
When the conversion of the signals given from the I51 and 1120 integration circuits 53 is completed, the interrupt request signal becomes m! oMPU62 Hiro applied to the i-microcombi and -ta through the $8 meeting.
In response to this interrupt request, 1B executes the interrupt processing routine shown in FIG.

First, in step 76, it is determined whether the current integration operation (currently being performed is for the back ground detection period).If it is the background detection period, step 7
7--Proceed and store the false conversion value Dad as b in a predetermined position VC of the RAM 64. Also, if it is not the background detection period, that is, if it is the knocking detection period, proceed to step 78 and store the false conversion value Dad as the knowledge conversion value Dadt-a. RAM6
40 stored in a predetermined position. When the processing in step 77 or 78 is completed, the process returns to the main routine.

On the other hand, when the time of the soft timer reaches t, a time interrupt request is generated, and as a result, the kiPU 62 executes the interrupt processing routine shown in FIG. 187. First, in step 79, the integral instruction signal outputted via the helix 55 is
The second integrating circuit 53 starts the integrating operation by inverting the signal to #. Next, in step 80, the time t4t at which the knocking detection period ends - the calculated 0 crank angle displacement 11 at the end of the knocking detection period (for example, 500CA.'A
TDC) is determined in advance, so the calculation method in step 80 is almost the same as that in step 71. When the processing in step 80 is completed, the process returns to the main routine.

When the soft timer reaches time t4, a time interrupt request is generated - this causes the MPU 62 to interrupt the IK8 diagram
Execute I&ring routine. First, in step 81, the integration instruction signal via the line 5S is inverted to %0#,
112, complete the integration operation of the integration circuit 53. Next, the process advances to step 82 and B.

@b is the value obtained by multiplying the average value of the output amplitude of the knock sensor 12 during the knock detection period by btK (however, K is a constant), and the knock sensor 12 during the knock detection period is expressed as @b. 12
A comparison is made between the value a and the value a corresponding to the maximum value of the output amplitude. If a≧Kmb, knocking occurs;
If a<K@bO, it is determined that knockinda does not occur◎
If it is determined that knocking has occurred, the process proceeds to step 83 and sets knocking 7 lag Fk 1% 1#.

Further, it is determined that there is no knocking, and the process proceeds to critical event step 84, where the knocking 7 lag Fk is reset to 101. When the processing in step 83 or 84 is completed, 11
The routine shown in FIG. 8 is ended and the main routine is returned. When the knocking 7 lag Fk is 111, in step 70 of FIG. 3, the calculated optimum ignition timing telΔt
The mouth that is controlled in the unidirectional direction, that is, the ignition time t# is turned off←t
Knocking can be suppressed by controlling θ=tK.

Although it is not shown in the diagram, when the soft timer time reaches t#, ignition timing interrupt processing occurs, and this
By the way, Figure 1B9, where the ignition timing control is performed, is a detailed explanation of the present invention described above.
The figure shows the waveforms of the ignition signal, knock sensor output, and integral instruction signal when the ignition timing is relatively advanced.
(B) shows each waveform according to the conventional technique when the ignition timing is relatively delayed, and 0 represents the combined waveform according to the method of the present invention when the ignition timing is relatively delayed. Conventionally, when the ignition timing is relatively advanced (Fig. 1119)
In the case where K is also relatively delayed, the pack ground detection period Tl is always fixed within a constant crank angle range. However, according to the present invention, Figure 119 (Q
As shown in K, if the ignition timing is delayed, the pack ground detection period T! becomes longer, and a more accurate background signal can be obtained accordingly. Furthermore, when the ignition timing is advanced, the pack ground detection period T becomes shorter as shown in FIG. 9 (4), so that the knock sensor output Kt during this period is not affected by undesirable noise similar to ignition noise. In this sense, it is possible to obtain a stable and noise-resistant packed ground signal. Furthermore, according to Figure 119,
T indicates the knocking detection period, SL indicates the valve striking noise, S8 indicates the ignition noise, and a indicates the knocking.

As explained in detail above, according to the method of the present invention, it is possible to obtain a stable and accurate background signal that is resistant to noise, so that highly accurate and reliable knocking detection can be performed. Can do 0

[Brief explanation of drawings]

Figure 11 is an overall schematic configuration diagram of an embodiment of the present invention,
112Ii1 is a block diagram of the control circuit shown in FIG. 1111, FIGS. 3 to 118 are flowcharts of each side-in processing routine of the control circuit, and FIG. 11E9 is a diagram explaining the operation of the above embodiment. 10... Cylinder block, 12...
Knock Senna, 14...Distributor,
16.18...Crank angle senna, 20...
... Control circuit, 36°46 ... Input/output board, 48 ... Parameter and filter circuit, 50.
... Rectifier circuit, 51.53 Old... Integral circuit, 5
4......~b converter, 62......MPU,
64...RAM, 66...ROM Patent Applicant Toba Jidosha Kogyo Co., Ltd. Patent Application Agent Akira Saneki Patent Attorney Kazutoshi Nishidate / Patent Attorney Akiyuki Yamaguchi 62

Claims (1)

[Claims] 1@ At least one vibration detection element that converts mechanical vibration into amplitude fluctuation of an electrical signal is installed in the engine body, and the crank angle range before the top dead center of at least one cylinder is determined in advance. The amplitude value of the electric signal from the vibration detection element is stored, and the amplitude value of the electric signal in a predetermined 112 crank angle range after ignition of at least one cylinder is stored. Comparing the size with the 9th case, it is κ.9The ignition timing of the predetermined cylinder is calculated using the method of detecting the presence or absence of knocking (7b-), and the ignition timing of the above 1st case is Changing the crank angle range S1
A method for detecting knocking in a private engine characterized by: