JPS63309737A - Prevention for knocking in internal combustion engine - Google Patents

Abstract

PURPOSE:To easily prevent the generation of knocking by deflecting the intake or exhaust timing set at the max. output generation timing on the basis of the engine parameters, from the max. output generation timing, when knocking is generated. CONSTITUTION:In engine operation, a control circuit 16 mapsearches the base exhaust angle thetaT1 corresponding to the max. output generation timing according to the throttle opening degree thetaTH detected by a throttle sensor 32 and the engine revolution speed Ne obtained from the output pulse of a synchronous pulse generating means 23. Then, the base exhaust angle thetaT1 is corrected by a prescribed correction value and changed to a standard exhaust angle thetaT, and an aimed exhaust angle thetaAT is obtained by dividing the standard exhaust angle thetaT by the correction coefficient obtained on the basis of the variation of the throttle opening degree. If the generation of knocking is detected by a vibration sensor 17 in this case, the exhaust angle correction value thetaTO is obtained in correspondence with the knocking level, and the exhaust timing is controlled so as to deflect from the max. output generating timing.

Description

[Detailed description of the invention] Technical field The present invention relates to a method for suppressing knocking in an internal combustion engine.

Background Art In order to improve the output performance of internal combustion engines such as 2-stroke engines, 4-stroke engines, and rotary engines,
Methods of controlling the intake or exhaust timing of internal combustion engines are known. For example, in Japanese Patent Application Laid-open No. 62-20622,
A 2-stroke engine is shown that is equipped with a control device that makes the position of the upper edge of the exhaust port of the 2-stroke engine variable and controls the position of the upper edge of the exhaust port according to engine parameters such as engine speed to control its output. has been done.

SUMMARY OF THE INVENTION An object of the present invention is to provide a knocking suppression method for an internal combustion engine that can suppress knocking by controlling the intake or exhaust timing of an internal combustion engine that is equipped with a control device that controls the intake or exhaust timing. There is.

In the knocking suppression method for an internal combustion engine according to the present invention, when knocking occurs, the intake or exhaust timing is set to the maximum output generation timing based on the engine parameters of the internal combustion engine equipped with a control device for controlling the intake or exhaust timing. It is characterized by making it deviate from the maximum output generation time.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of an apparatus in which the method for suppressing knocking of an internal combustion engine according to the present invention is applied to a two-stroke engine mounted on a motorcycle.

The two-stroke engine 1 has an exhaust port 4 that opens into the cylinder 2 and is opened and closed by a piston 3. An exhaust pipe 6 in which an expansion chamber 5 is formed is communicated with the exhaust port 4 to form an exhaust passage. The expansion chamber 5 is formed in such a shape that its central portion swells in the exhaust flow direction and its both ends are narrowed, so that the so-called effect of exhaust reflected waves (kabunashi effect) can be utilized.

A flap plate 8 is attached to the upper edge of the exhaust port 4 and is pivotably connected to a rotation shaft 9. The rotation shaft 9 is an output shaft of a reducer 12 that reduces the rotational output of the pulse motor 10, and the flap plate 8 is pivoted in accordance with the rotational output of the pulse motor 10 and positioned at a desired angular position. The free end of the flap plate 8 is located at the upper edge of the exhaust port 4 and forms the upper edge of the exhaust port 4 . Therefore, by pivoting the flap plate 8, the upper edge position of the exhaust port 4 moves up and down, making it possible to change the exhaust timing. That is, the flap plate 8, the speed reducer 12, and the pulse motor 10 constitute an exhaust timing adjustment mechanism. Note that the pulse motor 10 is equipped with an encoder 1 for detecting its operating state.
The output signal of the encoder 13 is input to the address detection circuit 14, and the address signal indicating the operating position of the pulse motor 10 that drives the flap plate 8 is input from the address detection circuit 14 to the control circuit 16. It looks like this.

Engine 1 detects engine 1 vibration on the side of engine 1's cylinder block or cylinder head.
A vibration sensor 17 is provided that emits a vibration signal corresponding to the vibration of. The vibration signal output by the vibration sensor 17 is supplied to a band pass filter (hereinafter abbreviated as BPF) 18 that passes only the vibration signal in a frequency band specific to knocking, and only the vibration signal specific to knocking is sent to the control circuit 16 as a knocking level signal. The knocking level signal is input to the control circuit 6 via the A/D converter 19 in response to a knocking level signal supply command signal output from the knocking level signal supply command signal.

On the other hand, the synchronous pulse generating means 23 generates a rotation angle position signal (hereinafter referred to as
(referred to as B pulse).

Specifically, there is a known means for obtaining such a B pulse as an output signal of the magnetic pickup 23b by combining a magnetic pickup 23b with a rotor that rotates in synchronization with the rotation of the crankshaft 24 and has a large number of pawls 23a. It is.

Further, the reference position pulse generating means 25 generates a reference rotation angle position signal (hereinafter referred to as A pulse) indicating that the crankshaft 24 has reached a predetermined rotation angle position before TDC (piston top dead center), that is, a reference rotation angle position. occurs. This A-pulse can be obtained by separately providing an A-pulse claw 25a on the rotor used in the synchronous pulse generating circuit 23 and providing an A-pulse generating magnetic pickup 25b.

The fixed period clock 27 generates clock pulses of a predetermined period by frequency-dividing a clock signal from a high frequency clock source (not shown), and the clock pulses are input to a clock counter 28 . After being cleared by the B pulse, the clock counter 28 counts periodic clock pulses. That is, the count value of the clock counter 28 indicates the elapsed time after the B pulse is generated.

The control circuit 16 is composed of, for example, a microcomputer including a CPU ROM and a RAM, and performs arithmetic operations according to a main routine or an interrupt subroutine, which will be described later. Further, a throttle signal corresponding to the rotational position of the throttle grip 31 is inputted to the control circuit 6 from a throttle sensor 32 that detects the rotational position of the throttle grip 31 as a parameter indicating the throttle valve opening of the engine 1.

The control circuit 16 controls the flap plate 8 corresponding to the desired ignition angle θIG on the crank angle and the target exhaust timing at which the exhaust port 4 should start opening, based on the engine speed Ne calculated based on the above-mentioned B pulse and the throttle signal.
Target rotation angle position (hereinafter referred to as target exhaust angle) θAT
is calculated, and based on the calculation result, the ignition system 33 is triggered to cause the spark plug 34 to discharge a spark, and the pulse motor 10 is driven to adjust the exhaust timing.

FIGS. 2 to 5 show the setting operation of the ignition angle θIG and target exhaust angle θAT of the control circuit 16, and the crank angle set to the ignition angle θI.
When G is reached, the ignition is commanded and the flap plate 8
2 is a flowchart showing a main routine and a subroutine that control command operations for making the rotational angular position (exhaust angle) of the engine coincide with the target exhaust angle θAT.

As shown in FIG. 2, when the power is turned on, the main routine is sequentially executed step by step within the control circuit 16 in accordance with periodic clock pulses. First, in the first step S1, an initialization operation is performed.

Next, the current exhaust angle θV calculated by the address signal output from the address detection circuit 14 is compared with the target exhaust angle θAT obtained by executing a subroutine to be described later (steps S2 and S3), and the current exhaust angle is determined. θ
When the difference between V and the target exhaust angle θAT is larger than the predetermined value ε1, the drive circuit 36 is activated by the amount corresponding to the difference between the pulse motor 10 and the target exhaust angle θAT.
(Step S4°Ss).

FIG. 3 shows a flowchart of a periodic interrupt subroutine that is executed by interrupting the main routine at regular intervals. In this subroutine, when the main routine is interrupted, the throttle opening θTH and the engine speed Ne are first read (step S6), and the engine speed Ne and the throttle opening θ are read based on the map I stored in advance.
The base exhaust angle θ corresponds to the maximum output generation time when the maximum output is achieved at the engine rotation speed Ne according to TH.
Search T1 (step S7). Next, a reference exhaust angle 0 is set from the base exhaust angle θT1 and a correction value θTO set by executing a B pulse interrupt subroutine to be described later (step Ss).

Next, the throttle opening change ΔθTl−1 per unit time is obtained by subtracting the previous throttle opening θT+(n, +) from the current throttle opening θ■H(n) (step S9), and correction is made based on this ΔθTH. Find the coefficient N (step 5IO). The reference exhaust angle 0 set in step S8 is divided by the correction coefficient N to perform correction according to acceleration/deceleration to obtain the target exhaust angle θAT (step Sn). Whether the target exhaust angle θAT is within the rotation range from the upper end position to the lower end position of the flap plate 8, that is, whether the target exhaust angle θAT is within the range from the maximum exhaust angle θvn+ax to the minimum exhaust angle θvmjn. If the target exhaust angle θAT is not within that range, the maximum exhaust angle θvmax or the minimum exhaust angle θvmin is set as a new target exhaust angle θAT (step 'SI2.
SI3,5I41 8I5). Then, based on the map H stored in advance, the ignition angle θI at which the maximum output is obtained corresponds to the engine speed Ne and the throttle opening θTl-1.
Search for G (step 5I6). Incidentally, during the operation in the fixed period interrupt routine, the engine rotational speed Ne used for calculation is obtained by executing the B pulse interrupt subroutine to be described later.

FIG. 4 shows a flowchart of the B pulse interrupt subroutine. This subroutine is executed by interrupting the above-mentioned main routine or periodic interrupt subroutine in response to the B pulse. This subroutine is interrupted by the generation of the B pulse, and first the count value Tam of the clock counter 28 at the rising edge of the B pulse is calculated.
(m=0 to 7) and the count value CF (m) (m=0 to 7) of the built-in free run counter of the control circuit 16 are taken in (step 517). Next, the difference ΔMe between the current CF (m) and the previous CF (m-1) is calculated (step 518
). Next, the latest eight data values ΔMe(m-7),
ΔMe (+n-6),...ΔMe (m-1
), ΔMe (m) are added and this is set as Me (m) (step 519). Next, the reciprocal of Me (m) is set as the engine rotation speed Ne (step 520), the count value FS of the stage counter is crossed over and incremented (step S2+), and the count value FS becomes 5 (step S22.823). .521), a knock level signal supply command is issued to the A/D converter 19 (step 525). Incidentally, the count value FS is set to -1 every time an A pulse is generated based on the A pulse interrupt subroutine as shown in the flowchart shown in FIG. The A-pulse interrupt subroutine is a subroutine that interrupts the main routine, periodic interrupt subroutine, or B-pulse interrupt subroutine in response to the A pulse generated every time the crankshaft 24 rotates once.

When the count value FS reaches 6 in step S23,
Take in the knock level signal Vp (step 528),
The ignition angle correction value θIGO and the exhaust correction value θTo are calculated according to the knock level, that is, the strength of knocking (step S27. The reference ignition angle θI
, and the ignition angle correction value θIGO set in step S27 is divided by the engine rotational speed Ne to obtain the ignition timing TIG, and the TIG is calculated using the programmable count register (not shown) built in the control circuit 16. (Step 529). The register begins counting down the TIG (Step 530), and when the count reaches or falls below zero, the register
3 (step 531).

That is, when knocking occurs, the ignition angle correction value θIGO and the exhaust correction value θTO are adjusted according to the knock level.
is set, and the ignition timing is retarded in accordance with the ignition angle correction value θrcO to deviate from the ignition timing at which maximum output is obtained, resulting in a decrease in engine output. At the same time, the exhaust correction value θ
Depending on the TO, the exhaust timing is shifted to the retard side or the advance side from the maximum output generation time, and the exhaust reflected wave acts at a time shifted from the timing when the exhaust port closes.
Charging efficiency decreases and engine output decreases.

From the above, it is possible to avoid a knocking situation.

In addition, although the above-mentioned embodiment is a case where the present invention is applied to a two-stroke engine, the present invention is also applicable to a four-stroke engine and a rotary engine. Incidentally, the exhaust timing adjustment of the four-stroke engine can be easily controlled by the control circuit 16 if the valve mechanism is a solenoid valve using an electromagnet.

As described in detail, in the knocking suppression method for an internal combustion engine according to the present invention, when knocking occurs, the intake or exhaust timing is set at the maximum output generation timing based on the engine parameters of the internal combustion engine. Since the engine is biased from the timing, when knocking occurs, the engine output of the air-fuel mixture decreases, making it possible to suppress knocking.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the device when the present invention is applied to a two-stroke engine, and FIGS. 2 to 5 are flowcharts showing the operation of the embodiment of FIG. 1. Explanation of symbols for main parts 1... 2-cycle engine 4... Exhaust port 5... Expansion chamber 6... Exhaust pipe 8... Flap plate 10... Pulse motor 13... Encoder 14... Address detection circuit 16... Control circuit 23... Synchronous pulse generating means 24 ......Crankshaft 25...Reference position pulse generating means 27...
... Fixed period clock 28 ... Clock counter 31 ... Throttle grip 32 ... Throttle sensor 33 ... Ignition system

Claims (1)

[Claims] A method for suppressing knocking in an internal combustion engine capable of controlling intake or exhaust timing, wherein the intake or exhaust timing is set to a maximum output generation timing at which maximum output is obtained based on engine parameters of the internal combustion engine, and knocking in the internal combustion engine is suppressed. 1. A method for suppressing knocking in an internal combustion engine, comprising: detecting a knocking occurrence signal to obtain a knocking occurrence signal; and depending on the knocking occurrence signal, deviating the intake or exhaust timing from the maximum output generation timing.