JPS63263246A - Knocking control device for engine - Google Patents

Abstract

PURPOSE:To prevent lowering of engine output by changing engine control variable, the initial value of which is set at high octane number corresponding value, by octane number corresponding value changing means, when knocking is more than a designated value and when an engine is switched over to warming up. CONSTITUTION:A controller 37 is adapted to control a duty ratio signal value of a duty solenoid valve 26 from the initial set value (100%) to be reduced to 75%, 50%, 25% and 0% in order by octane number corresponding value changing means when the lag angle reaches a limit value due to an increase in knock pulse number of a knock sensor 35. According to the above control, the maximum supercharging pressure of an exhaust turbosupercharger 20 is lowered to restrain knocking. When the engine is cold, the maximum supercharging pressure is sometimes lowered to low octane number corresponding value by false detection of knocking even if high octane number fuel is used. When the engine is switched over to warming up, however, the duty ratio signal value is forcedly reset to the initial set value (100%) by reset means, so that the maximum supercharging pressure is returned to the high octane number corresponding value. Accordingly, knocking can be restrained effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improvement in an engine knock control device.
In particular, the present invention relates to measures to prevent knock control malfunction in engines that can use both high-octane fuel and low-octane fuel.

(Prior Art) Conventionally, as a knocking control device for this type of engine, a load range in which knocking occurs with high octane fuel is set in advance, as disclosed in, for example, Japanese Patent Laid-Open No. 60-75730. Initially, engine control variables such as compression ratio and ignition timing are initially set to values corresponding to high octane fuel, and if knocking occurs in a range other than the above set load range, low octane fuel is used. By determining that the engine is being used, the engine control amount is changed to a value corresponding to the low octane number corresponding to this low octane number fuel, and this is maintained until the engine stops. A known engine is one in which the control amount is optimally set to maintain good engine operating conditions.

(Problems to be Solved by the Invention) However, in the conventional system described above, although the engine control amount is made to correspond to the octane number of the fuel used to ensure good operating conditions, when the engine is cold,
If the above measures were not taken, the engine control amount would be incorrectly set to the value corresponding to the low octane fuel when using high octane fuel.
As a result, the output may be reduced even when the engine is warmed up, even though high octane fuel is used.

Therefore, the inventors of the present invention conducted intensive research to find out the cause of the above-mentioned output drop, and found that when the engine is cold, the gap between the piston and the cylinder is relatively large, so the piston hits the cylinder wall during the combustion stroke. It was learned that this hit was erroneously detected as knocking, and as a result, even when using high octane fuel, the engine control amount was erroneously set to the value corresponding to the low octane number, resulting in a reduction in output.

In view of the above, the present invention aims to prevent the engine from warming up after engine warm-up Ia, assuming that when noise occurs due to strong piston hitting, erroneous detection of knocking due to this noise is unavoidable. By forcibly resetting the control amount to a value corresponding to a high octane number, even if the value corresponding to a low octane number is accidentally set when the engine is cold, the engine control amount will be adjusted to the octane number of the fuel used after the engine warms up. Correspondingly, the objective is to effectively prevent a decrease in engine output when using high octane fuel.

(Means for Solving the Problems) In order to achieve the above object, the present invention is directed to a knocking control device for an engine in which low-octane fuel and high-octane fuel are used, as shown in FIG. . Initial setting means 50 initializes the control amount of the engine 1 to a high octane value corresponding to the high octane fuel.
and a knock detection means 35 for detecting knocking of the engine 1, and receiving the output of the knock detection means 35, when knocking of a predetermined value or more occurs, the engine control amount set by the initial setting means 50 corresponds to a high octane number. An octane number corresponding value changing means 51 is provided for changing the value to a low octane number corresponding value corresponding to low octane number fuel and maintaining the value. Based on this premise, the engine temperature detecting means 40 detects the engine temperature, and the output of the engine temperature detecting means 40 is received, and the engine temperature is shifted from the cold state to the warm state.
The configuration includes a reset means 52 for forcibly resetting the engine control amount to a value corresponding to a high octane number when the engine control amount is reached.

(Function) With the above configuration, in the present invention, the engine control amount is initially set to a value corresponding to a high octane number by the initial setting means 50,
If knocking of a predetermined value or higher is detected in this state, the octane number corresponding value changing means 51 changes the engine control amount to a low octane number corresponding value, and maintains this corresponding value.

Now, when using high octane fuel, when the engine is cold, the screws 1 to 1 hit the cylinder wall strongly and generate noise, and if knocking is falsely detected due to this, as described above. Octane value corresponding value changing means 51
The engine control wlli is changed to a value corresponding to a low octane number, but when the engine changes from cold to warm up, the reset means 52 forcibly resets the engine control amount to a value corresponding to a high octane number, so that the engine control amount is changed to a value corresponding to a low octane number. After warming up, the octane number of the fuel used and the setting of the engine control amount correspond well, and the engine output can be effectively improved as expected.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

FIG. 2 shows a schematic structure of the engine knocking control device according to the present invention, in which 1 is an engine, 2 is a combustion chamber formed by a piston 4 slidably inserted into a cylinder 3 of the engine, and 5 is a combustion chamber formed by a piston 4 slidably inserted into a cylinder 3 of the engine. An intake passage 7 has one end communicating with the atmosphere via the air cleaner 6 and the other end opening into the combustion chamber 2 to supply intake air to the combustion chamber 2; This is an exhaust passage that is open to the atmosphere and discharges exhaust gas. In the middle of the intake passage 5, there is a throttle valve 10 that controls the amount of intake air, and a fuel injection valve 11 that injects fuel toward the combustion chamber 2 downstream of the throttle valve 10.
A catalyst device 12 for purifying exhaust gas is interposed in the exhaust passage 7. Further, an ignition plug 13 for igniting the air-fuel mixture in the combustion chamber 2 is arranged at the top of the combustion chamber 2, and an intake valve 14 is arranged at the opening of the intake passage 5 to the combustion chamber 2. An exhaust valve 15 is arranged at each opening of the passage 7 into the combustion chamber 2 . Generally speaking, a fuel tank 19 is connected to the fuel injection valve 11 through a fuel supply passage 18 in which a fuel filter 17 is interposed, and the inside of the fuel tank 19 is filled with high octane fuel (high octane gasoline) and low octane fuel
(Regular gasoline) is supplied arbitrarily at different times.

Furthermore, a υ1-air turbocharger 20 is disposed across the intake passage 5 on the upstream side of the throttle valve 10 and the exhaust passage 7 on the upstream side of the catalyst device 12.

The exhaust turbo supercharging l
The throttle valve 10 of the intake passage 5 is drivingly connected via c.
The compressor 2ob is provided on the upstream side, and the compressor 120b is rotationally driven by the turbine 20a rotated by the exhaust gas flow to perform supercharging of intake air.

A bypass passage 22 that bypasses the exhaust turbo supercharging 620 is provided in the exhaust passage 7 near the exhaust turbo supercharging 120, and a waste gate that opens and closes the opening is provided at the upstream opening of the bypass passage 22. A valve 23 is arranged. A diaphragm device 25 for opening and closing the wastegate valve 23 is connected to the wastegate valve 23, and the diaphragm device 25 includes a pressure chamber 25b and a spring chamber 25C partitioned to the right in the figure by a diaphragm 25a. A spring 25d is compressed, and a duty solenoid valve 26 is connected to the pressure chamber 25b. The duty solenoid valve 26 receives the pressure of the intake passage 5 on the downstream side of the compressor 20b of the exhaust turbo supercharging fi 120, that is, the supercharging pressure, through the pressure passage 27, and also introduces the pressure on the intake passage 5 downstream of the compressor 20b through the open passage 28. When the side intake passage 5 is opened and the duty ratio is 0%, the open passage 28 is closed and the supercharging pressure itself is directly applied to the pressure chamber 25b of the diaphragm device 25. , when the boost pressure rises to a boost pressure value PL that is greater than the biasing force of the spring 25d, the diaphragm 25 is compressed while the spring 25d is compressed.
a to open the wastegate valve 23, while when the duty ratio is 100%, the pressure passage 27 is communicated with the open passage 28 with the maximum opening area to lower the pressure value acting on the pressure chamber 25b, Correspondingly, the wastegate valve 23 is made to listen to the supercharging pressure IP+-+ which is higher than the supercharging pressure value PL. In addition, 29 is exhaust tartar supercharging 1a20
An intercooler 30 cools the supercharged air, and an igniter 30 adjusts the ignition timing at the spark plug 13.

A knock sensor 35 serving as a knock detection means for detecting knocking is arranged around the cylinder 3 of the engine 1, and its detection signal is inputted via a knock adapter 36 to a controller 37 containing a CPLJ and the like. There is. ``Also, 38 is an air flow sensor that is placed directly downstream of the air cleaner 6 and measures the amount of intake air, 39 is an intake air temperature sensor that is upstream of the air flow sensor 38 and detects the temperature of the intake air, and 40 is an air flow sensor that measures the intake air amount by measuring the temperature of the engine cooling water. A cooling water temperature sensor as an engine temperature detection means for detecting temperature; 41 an opening sensor for detecting the opening of the throttle valve 10; 42 a distributor as an engine rotation speed sensor;
The detection is input to the controller 37. The controller 37 controls the operation of the fuel injection valve 11, the duty electromagnetic valve 26, and the igniter 30, respectively. In addition, in Fig. 2, 43 indicates O when the engine 1 is started.
This is a starter switch that is operated by N.

Next, control of the fuel injection amount, ignition timing, and maximum boost pressure by the controllers 1 to 37 is shown in FIGS. 3(a) and 3(b).
The explanation will be based on the flowchart diagram.

3(a), after turning on the power by turning on the ignition switch in step S+, assuming that the fuel used is high octane fuel, a control signal is sent to the duty solenoid valve 26 in step S2. The duty ratio signal value DRE c is set to 100%, the maximum supercharging pressure of the exhaust turbo supercharging 131t20 is initially set to the supercharging pressure value PH, and the retard amount of the ignition timing of the spark plug 13 is OK in step S3. Initialize to the reference value (0°cA). Further, in step S4, the engine coolant temperature from the coolant temperature sensor 40 is detected, and in step S5
Then, the intake air temperature from the intake air humidity sensor 39 is detected.

After that, in step S6, the starter switch 43 is turned on.
Determine the presence or absence of operation, and if YES at ON operation,
In step S7, it is determined that it is time to start the engine, and the system waits as it is.
After the engine is turned OFF and complete explosion, the engine rotation speed Ne from the distributor 42 is detected in step S8, and the intake air IQ per engine rotation is detected in step S3.
are calculated, and based on these values, the fuel injection ff1Tp from the fuel injection valve 11 is calculated in step 310.

Then, in step 3o, the engine speed NO is compared in size with an extremely low speed value (for example, 500 ppm), and Ne < 5
If oorpm is YES, it is determined in step S7 that the engine is starting or stalled, and the process returns to step S6.

On the other hand, after completion of starting, first, in step S12, the engine rotation speed No. is determined, and in step 313, fuel injection is performed. 1
) Jffl (injection pulse width) Tp, Ne < 1
In each case of 50Orpm and Tp <2m5ec, the control range is not reached, so the duty control value DWC of the duty solenoid valve 26 is set to "0" value in step S14, and the ignition is turned off in step 315 of the same figure (b). The above operations are repeated until the engine is stopped by turning the switch OFF.

On the other hand, in steps 312 and S13 above, Ne≧150O
If YES for rpm and Tp≧2m5ec, it is determined in step 316 that it is in the knock control and maximum boost pressure control region, and the duty ratio signal value DRE c to the duty solenoid valve 26 is initialized in step 317. Value (10
0%), knocking control is performed using the ignition timing and maximum boost pressure from step S+a onwards.

That is, first, in step S+a, the signal waveform from the knock sensor 35 is input, and since the number of pulses is proportional to the knock intensity, the number of knock pulses is counted, and if the number of knock pulses = O, the ignition timing is advanced. Step 3
In step 19, the duration T is measured, and if it is 1560 m5eC, in step 320, the ignition timing retard amount θK (i) is changed to the previous value θK (i-
1) and hold it, while in the case of T>60m5ec, in step 321, a minute value (for example, 0.234°) is subtracted from the previous value θK(i-1), and the angle is selected by that amount. After that, in step S22, the current retard amount θ
Knowing the value of K(i), if θK(i)<O,
In particular, in step 32, in order to prevent advance angle control beyond the reference value.
In step 3, θK (i) is corrected to 0 and the process proceeds to step 325.

In addition, if the number of knock pulses≠O in step Sea, this means that knocking has occurred, so the ignition timing is retarded, and in step 324, the retard amount θK(i-1) of the previous ignition timing is adjusted. On the other hand, the current torque rotation θK(1) is increased by adding the torque rotation θRET per knocking pulse which increases according to the increase in the number of knock pulses, and then the process proceeds to step 325.

Then, in step 325, the ignition timing retard amount OK is compared with a limit value (for example, 6°cA), and if θ is ≦6°CA, it is determined that knocking can be sufficiently suppressed by ignition timing control. , immediately proceed to step 3 in Figure 3 (b).
35, the duty ratio signal value DRE c of the duty solenoid valve 26 at that time is determined by the step S force (initially 1
00%) by the intake air temperature correction coefficient CAT, which has a characteristic that gradually decreases as the intake air temperature increases as shown in FIG.
After calculating WG and correcting the maximum boost pressure value to be lower at high intake air temperature to ensure engine reliability, step S
's, if it is determined that the engine is running, step S.
Return to step 4 and repeat the above steps.

On the other hand, if θK > 6°cA in step 325, it is determined that the maximum boost pressure control is 8 indigo to suppress knocking, and the ignition timing is adjusted to a θK in step 326.
After correcting to the limit value (6° cA), in step S27 of FIG. 3(b), the duty ratio signal value DRE G (initially 100%) to the duty solenoid valve 26 is reduced by 25%, The maximum boost pressure value will be lowered accordingly to effectively suppress knocking.

After that, since it was decided to lower the maximum boost pressure value, step 328
On the condition that the duty ratio times @value DREG is DREG≧0, the predetermined time t (for example, 10
After setting the timer of 0m5C), the timer value is sequentially counted down in step S30, and after waiting for the timer value to reach 0 in step 331, in step S32, the 7M value ("0 ” value).

After that, the ignition timing is retarded again, and when it reaches the limit value,
As mentioned above, lower the maximum boost pressure value and adjust the ignition timing.
Repeat the process of returning to the %t-value, and finally perform step 3 above.
When DREc<Q in step 28, the duty ratio signal value DRE a is corrected to the "011 value" in step 333, and the maximum boost pressure of the exhaust turbo supercharger 20 is maintained at the boost pressure value PL.

After that, in step 334, the engine coolant temperature from the coolant temperature sensor 40 is grasped, and the previous temperature value T
H Town l-1) and the current temperature value T11W(I) are Tl!
When W(1-1)<85°C, TH stomach (I)≧85°C,
In other words, this is the first time the temperature has exceeded 85 degrees Celsius. It is determined whether or not the engine is transitioning from a cold state to a warm-up state, and if it is not the time of transition, the duty ratio signal value DRE c (initially 100%) of the duty electromagnetic valve 26 is set to the duty ratio signal value DRE c (initially 100%) as shown in FIG. After calculating the duty control value Dwc by multiplying by the intake air temperature correction coefficient CAT shown in FIG. .

On the other hand, if the engine transitions from cold to ttat in step 334, the process advances to step S36, and in step 336, the duty ratio times the value DRE(1,
After resetting to 100% of the initial value, in order to reset it again after a predetermined period of time (for example, 5 minutes and 30 seconds), taking into account fluctuations in the cooling water temperature due to the operation of 1)-mostat in the engine cooling water passage, etc. The predetermined time is set in step 337, the timer 1 is counted down in step 53B, the timer value reaches the "011" value in step 339, and the duty ratio signal value DRE (
, to the initial value of 100% again, and step 33
Proceed to step 5.

Therefore, in the control flow of FIG. 3, in step S2, the duty ratio signal value DRE (, is initially set to 100
%, and the maximum supercharging pressure (engine control amount) by the exhaust turbo supercharging 120 is initially set to a supercharging pressure value PH corresponding to high octane fuel (tf1 corresponding to high octane fuel). 50.

In addition, by steps 312 to S18 and S24 to S in the figure, the ignition timing retard θK is set to the limit value (6°C^).
Reached: When knocking occurs above a predetermined value, the duty ratio signal value DRE of the duty solenoid valve 26 is
c, from 100% in 25% increments to obtain the supercharging pressure value P)- of the maximum supercharging pressure initially set by the initial setting means 50.
1 is gradually lowered in steps to obtain the duty ratio signal value DR.
At the time of 0% of E c, the maximum boost pressure is set to the boost pressure value PL (low octane corresponding value corresponding to low octane fuel, PL<
The octane number corresponding value changing means 51 is configured to gradually change and maintain the octane number (PH).

Roughly speaking, in steps S34 and 338 of the same figure, when the engine temperature rises to 85°C or higher based on the output of the cooling water temperature sensor 40 (at the time of transition from engine cold to warm-up), the duty solenoid valve is activated. 26 duty ratio times @ value D
r< E c is returned to 100%, the operation of the octane number corresponding value changing means 51 is stopped, and the maximum supercharging pressure value is forcibly reset to the supercharging pressure value P+1 (high octane number corresponding value). This constitutes the reset means 52.

Therefore, in the above embodiment, as shown in FIG. 5, when the number of knock pulses of the knock sensor 35 increases,
The ignition timing start value θK increases, the ignition timing is retarded, and knocking is suppressed. When knocking occurs again, the above-mentioned ignition timing retard control is repeated, and when the retard nθK reaches the limit value (6°cA), the duty ratio signal value DRE G of the duty solenoid valve 26 changes again. The octane number corresponding value changing means 51 slightly controls the initial setting value (ioo%) to 75%, and the maximum boost pressure due to the exhaust turbo supercharging m20 is reduced by that amount, and the supercharging pressure value P+ is reduced accordingly. The reduction in pressure effectively suppresses knocking. At this time, the ignition timing is set to the standard value (θ
= 0).

Therefore, when the fuel supplied to the fuel tank 19 is a high octane fuel, knocking occurs less frequently, the duty ratio signal value DREc remains at about 75%, and the maximum boost pressure value remains at about 75%. The supercharging pressure value PH (value corresponding to high octane number) is maintained near the above-mentioned boost pressure value, thereby ensuring an increase in engine output. On the other hand, when low octane fuel is used, the initial setting of the maximum boost pressure is the value corresponding to the high octane number (boost pressure value P1), so knocking occurs more frequently, and therefore the duty cycle is lower. The ratio signal value DREG changes from the initial setting value (100%) to 0% after passing through 75%, 50%, and 25%.
The maximum boost pressure gradually decreases to the boost pressure value PL (low octane corresponding value), and knocking is effectively suppressed.

Now, when the engine is cold and the engine coolant temperature is lower than the predetermined temperature (85 degrees Celsius), the gap between the piston 4 and the cylinder 3 is relatively large, and the noise caused by the strong contact between the two is falsely detected as knocking by the knock sensor 35. Therefore, even when using high octane fuel, the maximum boost pressure may drop to the boost pressure value PL (a value corresponding to a low octane number).

However, when the engine coolant temperature reaches a predetermined temperature (85° C.) or higher and the engine enters the warm-up state, the duty ratio signal value DREG is forcibly reset to the initial setting value (100%) by the reset means 52. As a result, the maximum boost pressure value is returned to boost pressure value P) - 1 (value corresponding to high octane number), so when the engine is warmed up, the setting of high octane fuel and engine control amount (maximum boost pressure value) corresponds well, and an increase in engine output is ensured. When using low octane fuel, the maximum boost pressure is returned to the value corresponding to the high octane number (supercharging pressure value P)4) when the engine warms up, but after that the maximum boost pressure is returned to the value corresponding to the low octane number (supercharging pressure value P)4). Since the pressure value PL) decreases to the pressure value PL), there is no problem in suppressing knocking.

In the above embodiment, the maximum boost pressure value was gradually lowered to a value corresponding to a low octane number (supercharge pressure value PL) only when retard control of ignition timing was not sufficient. Of course, the engine control amount for suppressing knocking may be performed by controlling the boost pressure only, and the engine control amount for suppressing knocking may be the ignition timing or the air-fuel ratio of the air-fuel mixture in addition to the boost control.

(Effects of the Invention) As explained above, according to the present invention, the engine control amount is initially set to a value corresponding to high octane fuel, and when knocking of a predetermined value or more is detected, the engine control amount is set to correspond to low octane fuel. When changing and maintaining the value, the engine control amount was forcibly reset to the value corresponding to high octane fuel #l when the engine transitioned from cold to warm, so the use of high octane fuel was Also in this case, it is possible to cancel out erroneous control caused by noise generated when the engine is cold, and effectively ensure an increase in engine output when the engine is warmed up.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention. Figures 2 to 5 show embodiments of the present invention, with Figure 2 being a general schematic diagram, Figures 3 (a) and (b) being a flowchart showing the operation of the controller, and Figure 4 being the intake air temperature. FIG. 5 is a characteristic diagram of the correction coefficient of the maximum boost pressure with respect to the maximum boost pressure. 1... Engine, 13... Spark plug, 19...
Fuel tank, 20... Exhaust turbo supercharger, 23...
Westgut valve, 26...Duty solenoid valve, 35
... Knock sensor, 37 ... Controller 1 to roller, 40
...Cooling water temperature sensor V, 50...Initial setting means, 5
1... Octane value corresponding value changing means, 52... Resetting means.

Claims (1)

[Claims] (1) A knocking control device for an engine in which low octane fuel and high octane fuel are used, which includes an initial setting means for initially setting an engine control amount to a high octane corresponding value corresponding to the high octane fuel, and a knock detection means for detecting knocking; and upon receiving the output of the knock detection means, when knocking of a predetermined value or more occurs, a value corresponding to the high octane value of the engine control amount set by the initial setting means is set to a low octane value corresponding to the low octane fuel. octane number corresponding value changing means for changing and maintaining the corresponding value, further comprising an engine temperature detecting means for detecting the engine temperature, and receiving an output of the engine temperature detecting means;
An engine knocking control device comprising a reset means for forcibly resetting an engine control amount to a value corresponding to high octane when the engine transitions from a cold state to a warm state.