JPS5939973A - Control of knocking of internal-combustion engine - Google Patents

Abstract

PURPOSE:To simplify the construction of a standard-value taking-in circuit by carrying-out sampling for the standard values when the max. value of knocking signal is detected, in an apparatus for detecting knocking by comparing the max. value signal of knocking output with the standard value. CONSTITUTION:The output signal of a knocking sensor 12 is transmitted into a peak-hold circuit 50 and a rectifying circuit 51 through a circuit 48 consisting of a buffer for impedance change and a band-path filter having the frequency band which is intrinsic to knocking as pass band. Said peak-hold circuit 50 takes-in the output of the knocking sensor 12 only when the signal in 1-level is applied from a microcomputer through a line 52 and an input and output port 46. The rectifying circuit 51 rectifies the signal of the knocking sensor 12 and inputs said signal into an integration circuit 55. The output of said integration circuit becomes the standard value for judging knocking. Sampling for the output of said integration circuit 55 is carried-out when the peak value is detected. Thus, the construction of the standard-value taking-in circuit can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting the occurrence of knocking in accordance with the output of a knock sensor and controlling knocking.

When knocking that occurs due to abnormal combustion in an engine is detected by a vibration detection element or an acoustic detection element called a knock sensor, the amplitude of the electric signal output from the knock sensor is compared with a comparison reference value. It is then determined whether the detected vibration is actually caused by knocking.

In this case, without fixing the comparison reference value to a constant value, by changing the comparison reference value according to the output signal (pack ground signal) that is considered to be unrelated to the knocking of the knock sensor, it is possible to reduce the variation in the knock sensor over time. It becomes possible to compensate for changes, etc. If the value of the pack ground signal is b, the comparison reference value is usually given by K-b.

However, K is a constant. The pack ground signal is normally a signal that represents the average value of the knock sensor output, but in order to stabilize this pack ground signal, it is necessary to detect the average value of the knock sensor output just before knocking occurs. It is most desirable to do so.

Therefore, in a knocking control system using a microcomputer, the average value of the output of the knock sensor is continuously detected by an integrating circuit, etc., and the output of the integrating circuit is calculated at a timing immediately before knocking occurs. The data is converted and input into a microcomputer.

In addition, in order to prevent noise such as pulp hitting noise from entering the knock sensor output and erroneously detecting that knocking has occurred, the maximum value of the knock sensor output within a predetermined period in which knocking may occur is detected. Normally, the knocking signal is compared with the above-mentioned comparison reference value.

The above-mentioned predetermined period, that is, the knocking signal acquisition period (
This period (hereinafter referred to as the period in which the knock gate is on) is usually selected from around TDC of each cylinder to around ATDC 60'CA.

As mentioned above, according to the conventional knocking control method,
Knocking signal acquisition period (knock dirt on period)
It is necessary to set various timings such as a timing for setting and a timing for taking in a ground signal, which causes the problem that the configuration of the timing circuit inevitably becomes complicated.

Therefore, the present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide a knocking control method that can reduce the number of timing signals for signal acquisition from a knock sensor. It's about doing.

A feature of the present invention that achieves the above-mentioned object is to detect the maximum value of the output of the knock sensor during a predetermined period after ignition, detect the average value of the output of the knock sensor, and compare the detected maximum value with the detected value. In the knocking control method, the knocking control method detects the occurrence of knocking by comparing the average value with a comparison reference value determined according to the average value, and controls the knocking so as to reduce the occurrence of knocking according to the detection result. The purpose of the present invention is to synchronize the timing of taking in the average value with the start timing of the maximum value detection period.

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 same figure, lO is a cylinder block of a 4-cycle 6-cylinder internal combustion engine, 12 is a cylinder pro, and lO
This is a knock sensor installed in the. Knock sensor 1
Reference numeral 2 is a well-known device that is composed of, for example, a piezoelectric element or an electromagnetic element, and converts mechanical vibrations into electrical amplitude fluctuations.

In FIG. 1, 14 further indicates a distributor, and this distributor 14 is provided with crank angle sensors 16 and 18. The crank angle sensor 16 is for cylinder discrimination, and if this engine has 6 cylinders, one no. occurs. The occurrence position is, for example, the first
It is set at a position slightly before the top dead center of the cylinder. The crank angle sensor 18 generates 24 pulses for each revolution of the distributor shaft, and therefore for every crank angle 306.

Electric signals from the knock sensor 12 and crank angle sensors 16 and 18 are sent to a control circuit 20. The control circuit 20 is further fed with a signal representing the intake air flow rate from an air flow sensor 24 provided in the intake passage 22 of the engine. On the other hand, from the control circuit 20, the igniter 2
An ignition signal is output to the igniter 26, and the spark current generated by the igniter 26 is distributed to the ignition pins 28 of each cylinder via the distributor 14.

The engine is usually provided with various other sensors that detect operating state parameters, and the control circuit 20 also controls the fuel injection valve 29, etc., but these are not directly related to the present invention. Therefore, all of these will be omitted in the following explanation.

FIG. 2 is a schematic diagram showing an example of the configuration of the control circuit 20 shown in FIG. The voltage signal from the airflow sensor 24 is converted into an analog multi-signal signal via the filter 30. 32
The signal is selected according to an instruction from the microcomputer and applied to the N-signal converter 34, where it is converted into a 2-pass signal and then input into the microcomputer via the input/output port 36.

Pulses for every 720' crank angle from the crank angle sensor 16 and pulses for every 306 crank angle from the crank angle sensor 18 are sent to the microcomputer via the input/output port 46 via the input/output port 46, respectively. It will be done.

The output signal of the knock sensor 12 is in a frequency band (7 to 8 KH) specific to impedance conversion and knocking.
z) is the passband/? The signal is sent to a peak hold circuit 50 and a rectifier circuit 51 via a circuit 48 consisting of a filter. The peak hold circuit 50
Only when a signal of level 11# is applied from the microcomputer through the input/output port 46, the output signal from the knock sensor 12 is received and the maximum amplitude is held. The output of the peak hold circuit 50 is sent to the analog multiplexer 53, selected according to instructions from the microcomputer, and applied to the N raw converter 54, where it is converted into two communication signals and then sent to the input/output port 46. is taken into the microcomputer via the The rectifier circuit 51 performs full-wave rectification or half-wave rectification of the output signal from the knock sensor 12. The rectified signal is sent to an integration circuit 55 and integrated with respect to time.

Therefore, the output of the integrating circuit 55 is a value obtained by averaging the amplitudes of the output signals of the knock sensor 12. The output of the integrating circuit 55 is sent to an analog multiplexer 53, selectively applied to a converter 54, converted into two signals, and then input into the microcomputer. However, the input/output port 46 and the line 56
This is performed by an N raw conversion activation signal applied from a microcomputer via a microcomputer. Further, when the N raw conversion is completed, the N raw converter 54 notifies the microcomputer of the completion of the raw conversion via the line 58 and the input/output port 46.

On the other hand, when an ignition signal is output from the microcomputer to the drive circuit 60 via the input/output port 46, this is converted into a drive signal and the igniter 26 is energized, depending on the duration and duration of the ignition signal. ignition control is performed.

The microcomputer includes the aforementioned input/output ports 36 and 46, a microprocessor (MPU) 62, a random access memory (RAM) 64, a read-on memory (ROM) 66, a clock generation circuit (not shown), a memory control circuit, and the like. It mainly consists of a connected bus 68 and the like, and executes various processes according to control programs stored in the ROM 66.

Next, the operation of the microcomputer will be explained using a flowchart.

FIG. 83 shows a part of the initial processing routine and the main processing routine. When the engine ignition switch is turned on, the MPU 624d performs step 101.
The initial processing steps 102 and 102 are first executed, and then the main processing steps 103 to 107, some of which are shown in steps 103 to 107, are repeatedly executed.

In step 101, the input/output ports 36 and 46 are set to the initial state, and in step 102, the RAM 64 is cleared and initial data is set.

In the next step, Step 103, the clock of the input/output counter is defined by, for example, setting the timing cycle of A/b conversion. In the next step 104, an address is specified where the secrets of the program counter and register are to be saved when an interrupt occurs. In step 105, interrupt reception processing is performed.

In the next step 106, the intake air flow rate data Q sent from the air flow sensor 24 via the N raw converter 34 and stored in the RAM 64 and calculated by the interrupt processing routine of FIG. 4 are stored in the RAM 64. The stored engine rotational speed data Ne is taken in and Q/Ne is calculated. Next, in step 107, the basic advance angle θIIA8aC is determined from Q/Na and No using the basic advance angle map. A basic advance angle map for Q/Ne and No is stored in advance in the ROM 66, and in step 107, θBAgle is determined using interpolation calculation or the like. When the processing in step 107 is completed, other processing in the main processing routine is executed, and then step 103 is executed again.
Similar processing is repeated from then on.

FIG. 4 shows an interrupt processing routine that is executed every 30" of crank angle. This interrupt processing routine is executed when a pulse is applied from the crank angle sensor 18 every 30 degrees of crank angle. , calculation of rotational speed Ne,
Discrimination of cylinder in which ignition occurred TDC, 60° CA-BTD
It detects the positions of C and 30° CA-BTDC and performs the arithmetic processing required at each position.

When an interrupt occurs, the engine rotational speed Ne is first calculated in step 201. This is calculated from the difference between the free run counter values at the time of the previous interrupt and the time of the current interrupt.

In the next step 202, in step 301 of FIG.
It is checked whether the flag FG set to 1'' is 11#.

``NO#'', that is, the flag FG is set to FG=
In the case of O, the program advances to step ff7”203, and
0' Increment the CA interrupt count ω by 1.

That is, the process ω←ω+1 is performed.

On the other hand, if the determination in step 202 is "YES"', that is, if FG=1, the flag FG is reset to FG←0 in step 204, and the next step, f205, is 30°.
The number of CA interrupts ω is cleared to ``O''.

In this manner, in Stella f202 to 205, the number of 30'' CA interruptions ω is calculated from the reference position of each CA at 720 degrees from the crank angle sensor 16 as the starting point.

In step 206, the number of 30° CA interruptions ω is divided by a constant “4”, and the integer part of the calculated value ω/4 is set as the cylinder discrimination number n. This cylinder discrimination number n is not used in the present invention. In the sterag 207 of Wataru*Zume', the decimal part of the divided value ω/4 is set as the indicated value n' of the crank angle position. Here, the indicated value n
If 'kan' is 20, TDCS is 60' CA-BTDC if n' = 0.5, and if n' = 0.75 (7), it is 30' CA.

Each represents the crank angle position of BTDC.

In step 208, it is determined whether the above-mentioned instruction value n' is 0''. If n'=0, that is, the current 30'
If the CA interrupt matches the TDC of the compression stroke, the process advances to step 209 and the knock r-t on time t1 is determined.
is calculated, and in the next step 210, a value corresponding to this time t1 is set and tossed into the conveyor register A for starting the time coincidence interrupt.

Furthermore, the MPU 62 is provided with this conveyor register A and a conveyor register B, which will be described later, and are used for starting a time coincidence interrupt.

As mentioned above, the knock gate is a dirt means that is opened to detect a knocking signal from the output of the knock sensor 12. In this embodiment, the hold operation period of the peak hold circuit 50 is The knock r-) on period and other periods are the knock r-) off periods.

Next, the program proceeds to step 211 and executes the ignition timing calculation process detailed in FIG. Proceeding to Step 212, it is determined whether the indicated value n' is "(), 5".If n' = 0.5, that is, the current 3
If the 0°C8 interrupt corresponds to the 60°CA-BTDC, proceed to step f213-.

In step 213, the off time of the igniter 26, that is, the time at which ignition is to be performed, calculated together with the igniter on time in step 710 in FIG. do.

After the determination in step 7'' 212 is ``NO'' or after the execution of step 213, the program proceeds to step 214. Step 214 determines whether the indicated value n' is "0.75#".If gn'=0.75, that is, 3
In the case of 0°CA-BTDC, the program is
Proceed to step 15 and turn off the knock gate.

Next, in step 216, the peak hold circuit 5
The start of ~0 conversion of the 0 channel is indicated.

As a result, the wheat exchanger 54 operates as the peak hold circuit 5.
Therefore, N raw conversion of the knocking component a of the output of the knock sensor 12 is started.

After the determination in step 214 is ``No'' or steps 215 and 216 are executed, the program returns to the main processing routine shown in FIG.

The time when the conveyor register A is turned on, that is, the on-time t1 of the knock gate calculated in step 209 of FIG.
When the time A arrives, the MPU 62 executes the coincidence interrupt processing at time A shown in FIG.

That is, in step 401, the knock gate is turned on and the peak hold operation is started. Turning on the knock gate means inverting the signal applied to the peak hold circuit 50 via the input/output port 46 and the line 52 to "L", and as described above, the signal at the "L" level Peak hold operation is performed during this period. Next, in step 402, the start of Y[F] conversion of the channel of the integrating circuit 55 is instructed. As a result, the N wheat converter 54 starts NΦ conversion of the background component of the output of the integrating circuit 55, and thus the output of the knock sensor 12.

Upon receiving the notification of conversion completion from the N raw converter 54, the MP
U62 executes the interrupt processing shown in Fig. 8, and obtains the knocking signal value a or the pack ground value bf1%/T).
The data is taken in from the converter 54 and stored in the M64. First, in step 601, it is determined whether the current interrupt is an interrupt caused by the completion of replacing wheat in the peak hold circuit. If δelectric S'', the process advances to step 602, and the wheat test value at that time is set as the peak bold signal value a.If "No", the process advances to step 603, and the current N raw conversion value is used as the knocking signal value l. ).

When the time set in conveyor register B arrives, M
The PU 62 executes the JIIB match interrupt processing as shown in FIG. First, in step 501, it is determined whether or not the interrupt is related to the igniter on time. ″
If the answer is "No", that is, if the interrupt is related to the off time of the igniter 26 calculated in step 213 of FIG. ,As I mentioned before,
It is sent to the drive circuit 60 via the input/output port 46, and when it is reversed from on to off, the current to the ignition coil (not shown) stops at that point, and ignition spark occurs from the ignition plug. It is composed of

On the other hand, if "YES" is determined in step 501, that is, step 71 of the processing routine of FIG. 9, which will be described later.
If the interrupt is related to the igniter 260 on time calculated in step 0, the process proceeds to step 503 where the ignition signal is reversed from off to on. This starts energizing the ignition coil.

FIG. 9 shows step 211 in the interrupt processing routine of FIG. 4 in detail.

First, in step 701, it is determined whether the knocking value a obtained in the gauze conversion interrupt processing routine of FIG. . If ``YES'', that is, if a≧-b, it is determined that knocking has occurred and the process proceeds to Step 702; if ``NO#'', it is determined that knocking has not occurred and the process proceeds to Step 705.

Step 702 sets the ignition timing correction value θ□ to "l'cA".
The process is performed so that the ignition timing is delayed by l'CA.In the next step 703, the content of the color/rec, which is used as an argument for how many times knocking has not been detected, is initialized to '10'. Set.

The nologram then proceeds to step 704.

On the other hand, when it is determined that no knocking has occurred and the process proceeds to Step 705, it is determined whether the content of the counter C has become 0#. 1NO”, the counter C is incremented by one in step 706. ηIS#
In this case, that is, when no knocking occurs ten times in a row, the nologram proceeds to step 707, where the ignition timing correction value θ□ is increased by l'cA. Next, in step 708, the contents of the counter C are initialized to '10', and then the process proceeds to step 709. In this way, if no king occurs, θ□ decreases by l'cA (1
) and no knocking continues 10 times, θ□ is increased by 1'CA. In step 709,
At step 107 of the main processing routine in FIG.
The final ignition advance angle θ is calculated from the basic advance angle θR8° and the ignition timing correction value θ obtained as described above.θ←θB11
Calculated by 1+θ□.

In the next step, f710, the igniter 26 is
Find the off time of the igniter, in other words, the time when the ignition signal turns off, that is, the time when ignition is performed, and then find the on time of the igniter, that is, the time when the ignition coil starts to be energized, from the off time of the igniter, and calculate the calculated value. is set in conveyor register B for time match interrupt activation. When the process of step 710 is completed,! The program proceeds to step 212 of FIG.

FIG. 1O is a diagram showing signal waveforms and timing for explaining the detection operation of the knocking signal and back ground signal in the above-described embodiment.

As shown in FIG. 3B, the amplitude of the output of the knock sensor 12 changes depending on whether knocking occurs or not.

The integrating circuit 55 constantly integrates the output of the knock sensor 12, and therefore its output is as shown in FIG. The knock gate for detecting knocking signals is shown in the same figure)
As shown in , it turns on at time t1 after TDC of each cylinder, and turns off at 30° CA-BTDC of the next cylinder. This period in which the knock gate is on is set during a period in which vibrations based on the occurrence of knocking appear in the output of the knock sensor 12. During the r-tr-on period, the peak hold circuit 50 performs a tr-hold operation on the output of the knock sensor 12. Therefore, the output of the peak hold circuit 50 represents the knocking signal a as shown in FIG. The channel of the peak hold circuit 50, that is, the switching start of the knocking signal is performed at step 216 in FIG.
As explained above, this is done at the same timing as the turning off of Kudart (see Figure 10 (G)). Further, in the present invention, as shown in FIG. 10C), H conversion of the channel of the integrating circuit 55, that is, the pack ground signal, is started at the same timing as the ON of the signals F and F-).

Therefore, a timing circuit for starting the conversion of the background signal can be omitted. Furthermore, as is clear from Fig. 1θ (C), the knock gate ON timing is the time when the output of the integrating circuit 55 is most stable regardless of whether knocking occurs or not. If the pack ground signal is removed from the ground, a stable value can be obtained and the accuracy of knocking control can be improved.

As described in detail above, according to the present invention, the timing circuit for taking in the knock sensor output can be simplified, and a stable pack ground signal can be obtained, thereby improving knock control accuracy. You can get the special effect of being able to do this.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing an example of an internal combustion engine to which the present invention is applied, FIG. 2 is a diagram showing a detailed diagram of the control circuit shown in FIG. Flowchart of the processing routine, FIG. 1O is a time chart illustrating the operation of the processing routine. DESCRIPTION OF SYMBOLS 10... Cylinder block, 12... Knock sensor, 14... Distributor, 16, 18... Crank angle sensor, 20... Control circuit, 26... Igniter, 28... Ignition glove, 34, 54... ψ converter, 36.46... Input/output capo-1-148... Buffer and filter circuit, 50... Peak hold circuit, 51... Rectifier circuit, 55... Integrator circuit, 62・
・・MPU、64...～Akira、66...ROM
0 Patent Applicant Toyota Motor Corporation Patent Application Representative Patent Attorney w Hon Patent Attorney Kazuyuki Nishidate Patent Attorney Akira Yamaguchi Go to Step 212 (Figure 4) in Figure 9 Start in Figure 10

Claims (1)

[Claims] 1. Detecting the maximum value of the output of the knock sensor during a predetermined period after ignition, and detecting the average value of the output of the knock sensor, and a comparison standard determined according to the detected maximum value and the detected average value. In the knocking control method, the knocking control method detects whether or not knocking has occurred by comparing the knocking sensor output with the knocking sensor output value, and controls the knocking so as to reduce the knocking occurrence according to the detection result. 7. A method for controlling an internal combustion engine, characterized by synchronizing the start timing of the engine.