JPH0337034B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an engine control device.

(Prior Art) Engines may use high-octane fuel or regular fuel.
In a supercharged engine, since the occurrence of knocking is suppressed by using the former fuel, it is possible to set a high supercharging pressure and obtain high output.
However, if regular fuel is used in such settings, knocking is likely to occur due to the high supercharging pressure.

As means for preventing knocking, there are two methods: detecting engine knocking and retarding the ignition timing, and reducing boost pressure (for example, see Japanese Patent Laid-Open No. 167814/1983).
In the case of a method that retards the ignition timing, this retard is immediately reflected in the elimination of knocking, which means that the response is good, but the retard causes a decrease in output and increases the proportion of afterburning, which increases the exhaust temperature. . Additionally, although the continuation of knocking can be prevented, using a knock control system to always optimize the ignition timing means that knocking can always occur, which is not desirable from the standpoint of engine reliability. do not have. On the other hand, the boost pressure reduction method does not have the problem of an increase in exhaust temperature, but has the problem of a delayed response in that knocking is not immediately resolved even if knocking is detected and the boost pressure is lowered.

(Problems to be Solved by the Invention) The present invention attempts to employ both an ignition timing retard method and a supercharging pressure reduction method to prevent the above-mentioned knocking, and solves the following problems that occur in this case. It is something to do.

In other words, when detecting knocking and controlling the ignition timing and boost pressure at the same time, the ignition timing and boost pressure will return to their original values when the knocking is eliminated due to the retard and decrease. In addition, the above-mentioned retardation and reduction due to knocking are repeated, which tends to cause hunting. In addition, if knocking occurs and the boost pressure decreases with the retard of the ignition timing, if knocking occurs again during the response delay until this boost pressure drop is reflected in the elimination of the knocking, the previous boost pressure will decrease. Although knocking would normally be resolved by lowering the engine speed, the delayed response results in further retardation of the ignition timing and lowering of the boost pressure. Therefore, with such simultaneous control, it is difficult to set the ignition timing and boost pressure to the optimum settings at the same time, which tends to cause hunting in the control system, and also causes a large reduction in output due to excessive ignition timing retardation and a drop in boost pressure. will be invited. Furthermore, in any case, it is not desirable for the stability or reliability of the engine that the boost pressure fluctuates during transient times (during acceleration) when the engine is likely to knock.

Another possibility is to look at the amount of retard in the ignition timing and reduce the boost pressure accordingly.
There is a limit to the amount of retard from the perspective of preventing an excessive rise in exhaust temperature, and if a large knocking that exceeds a certain intensity occurs, the amount of retard at that time is constant regardless of its size, and therefore the boost pressure The amount of decrease is also constant. In other words, it is not possible to control the boost pressure according to the knocking strength, and conversely, it is only possible to roughly control the boost pressure without knowing the knocking strength. It is difficult to set the boost pressure to a critical point where knocking does not occur.

In short, ignition timing control and boost pressure control as countermeasures against knocking each have excellent characteristics, but in the past, these characteristics have not been effectively utilized.The present invention has been developed in view of these points. Therefore, the present invention aims to provide an engine control device that effectively utilizes the characteristics of both.

(Means for Solving the Problems) As a means for solving the above problems, the present invention provides an ignition timing adjustment means for adjusting the ignition timing of the engine in an engine equipped with a supercharger; A boost pressure adjustment means for adjusting boost pressure, a knock sensor for detecting engine knocking,
When knocking is detected in response to the output of the knock sensor in the first period, the amount of retardation of the ignition timing is determined according to the output of the knock sensor to retard the ignition timing, and when knocking is not detected, the amount of retardation of the ignition timing is determined. ignition timing control means for outputting an ignition timing control signal to the ignition timing adjustment means to gradually decrease the ignition timing; A supercharging pressure control means that determines the amount of reduction in supercharging pressure according to the output and outputs a supercharging pressure control signal to the supercharging pressure adjusting means to reduce the supercharging pressure, and Retard amount forced reduction means is provided for receiving the supply pressure reduction control signal and outputting a retard amount reduction signal to the ignition timing control means so as to reduce the retard amount of the ignition timing at that time faster than the gradual reduction rate of the retard amount. The present invention provides an engine control device.

(Function) In the case of the above engine control device, the ignition timing is controlled by the knock sensor output during the short first period, and the boost pressure is stabilized by the knock sensor output during the long second period while attempting to eliminate knocking with good response. This means that it can be controlled. Since the timing of control amount determination for ignition timing and boost pressure is fundamentally different depending on the settings of the first and second periods, respectively, hunting in the control is prevented, and
Since each of these is controlled based on the knock sensor output, it is possible to settle down to the optimum control value effective for preventing knocking with high precision. In addition, since the amount of retardation of the ignition timing is forcibly and rapidly reduced when boost pressure reduction control is performed, the state in which the ignition timing is excessively retarded even though the boost pressure has decreased is prevented. Subsequently, it is possible to prevent the engine output from temporarily decreasing unnecessarily.

(Effects of the Invention) Therefore, according to the present invention, by fully utilizing the characteristics of both ignition timing control and boost pressure control against knocking, the ignition timing can be adjusted while eliminating knocking with good responsiveness without causing control hunting. and supercharging pressure can be controlled with high precision to the optimum position.
Moreover, it is possible to prevent the ignition timing from remaining retarded for a long time even though the boost pressure has been lowered. It is possible to prevent fluctuations in the output of the engine and improve the durability and reliability of the engine.

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

In the engine control device whose overall configuration is shown in FIG. 1, 1 is a four-cylinder engine main body, and intake air from an air cleaner 2 is sent to an air flow meter 3, a compressor 4a of a supercharger 4, an intercooler 5, and a throttle chamber. 6 and surge tank 7
The air is supplied to the combustion chamber 11 above the piston 10 of the cylinder block 9 through an intake passage 8 which is interposed in order. Exhaust gas is discharged through an exhaust passage 12 in which a turbine 4b of the supercharger 4 is interposed. A fuel injection valve 13 faces the vicinity of the intake port of the intake passage 8, and the fuel injection valve 13 is connected to the fuel tank 14 through a fuel supply pipe 15 and a fuel return pipe 16.

The exhaust passage 12 has a turbine 4b of the supercharger 4.
A passage is provided to bypass the , and a waste gate valve 17 is interposed in this passage. The actuator 18 of this waste gate valve 17 is of a diaphragm type, and opens the waste gate valve 17 in response to pressure downstream of the compressor 4a. A duty solenoid valve 20 is interposed in the pressure passage 19 for the actuator 18.
This duty solenoid valve 20 has a duty ratio of 0% to minimize the amount of pressure escape to the upstream side of the compressor 4a (therefore, when the operating pressure of the actuator 18 is high, the wastegate valve 17 is fully open and the supercharging pressure is minimum), and the duty ratio is 0%. At 100%, the amount of pressure escape is maximum (therefore, the boost pressure is maximum).

A knock sensor 21 for detecting engine knocking is attached to the cylinder block 9, and receives an ignition signal (Ig pulse) from a distributor 24 that supplies high voltage to the spark plug 23 of the cylinder head 22 and the output of the knock sensor 21. Based on this, the controller 25 sends an ignition timing control signal and a supercharging pressure control signal to the ignition coil 26 as an ignition timing adjusting means and the duty solenoid valve 20 as a supercharging pressure adjusting means.

The throttle chamber 6 has two passages 27 and 28, a primary passage and a secondary passage, and is provided with throttle valves 29 and 30, respectively. The controller 25 controls the ignition timing retard amount θ(I) and the duty solenoid valve 20 with respect to the basic ignition timing and basic boost pressure set on the assumption that high-octane fuel is used in a four-cylinder engine.
It determines and outputs the duty of the second
As shown in the figure, a first cycle time determining unit 31 for determining the retard amount, a second cycle time determining unit 32 for determining the duty, a retard nook determining unit 33, a boost pressure control nok determining unit 34, Retard amount determining section 3
5. Retard amount output section 36, duty determining section 3
7, a duty output section 38 and a retard reset section 39 are provided.

That is, the first period determination unit 31 receives the ignition (Ig) pulse from the distributor 24 and determines whether 4Ig, during which all cylinders are ignited once, has elapsed. The second period determination unit 32 receives the ignition pulse and determines whether 16Ig has elapsed.

The retard knock determining section 33 calculates the number of knock pulses (knocking frequency) output from the knock sensor 21 during 4Ig. Between 16Ig (4Ig×4), the boost pressure control notch determination unit 34
Find the number of times 4 knock pulses are output during 4Ig. The retard amount determination unit 35 calculates a retard correction amount according to the number of knock pulses during 4Ig based on the determination by the retard knock determination unit 33, and determines the retard amount θ(I) from the basic ignition timing.
In this case, if there are knock pulses, a retard correction amount proportional to the number thereof is calculated, and if there are no knock pulses within the set time, a correction amount for gradually decreasing (advancing) the retard amount θ(I) is calculated. Further, this retard amount θ(I) shall not exceed the maximum allowable retard amount θ _MAX from the viewpoint of preventing an excessive rise in engine exhaust temperature. Retard amount output section 3
6 outputs an actuation signal corresponding to the determined retard amount θ(I) to the ignition coil 26.

The duty determining unit 37 determines the boost pressure reduction amount corresponding to the number of times the knock pulse is applied 4 times during 4Ig,
That is, the duty of the duty solenoid valve 20 is determined, and at that time, the current supercharging pressure is prevented from becoming high by comparing it with the current duty. The duty output section 38 outputs the determined duty pulse signal to the duty solenoid valve 20.

The retard reset section 39 constitutes a retard amount forced reduction means, and when it determines whether the determined duty is smaller than the current duty and performs control to reduce the boost pressure. Retard amount θ(I) after the set time T _RST has elapsed.
Make it zero.

The specific control flow is shown in Figure 3. The control starts at the same time as the ignition is turned on, and assuming high-octane fuel, θ(I) = 0,
Make the initial setting of duty = 100%, and proceed to the following flow every time an Ig pulse is input (step,
).

That is, the ignition timing control period counter T1 and the boost pressure control period counter T2 start counting by the Ig pulse, and the knock sensor 21 starts counting.
When the knock pulse is output from the knock flag
NF is counted up (step~).
Then, the counter T1 determines the first period, that is,
When it is determined that 4Ig has passed, the counter T1 is reset and the retard correction amount corresponding to the number of knock flags NF is added to the previous retard amount θ(I-1) to determine the retard amount θ(I). (Step ~). In this case, the knock flag NF is 4,
In the case of 3, 2, 1, the retard correction amounts are approximately 5 degrees, 4 degrees, 3 degrees, and 2 degrees in terms of crank angle. Also, in the step, the knock flag NF is 4.
In this case, four knock pulses are generated during 4Ig, and since boost pressure reduction control is required, the waste gate control flag WF for duty control is counted up in step.

Therefore, when the knock flag NF is zero in the first period (when the step judgment is NO), the timer (1) for gradually decreasing the ignition timing retard amount θ(I) is operated, and the timer ( If 1) is not reset within the set time (200ms), the retard amount θ
(I) is subtracted by 0.2 degrees, timer (1) is reset, and the retard amount θ(I), which has been subtracted by 0.2 degrees, is output (step ~). Therefore, from now on, unless a knock pulse is input, the retard amount θ(I) is changed approximately every 200ms by the operation of timer (1).
The reduction control will be performed until θ(I)=0.

On the other hand, when the knock flag NF is set at step , ,
, , when the ignition timing is retarded, the timer (1) is not activated and the timer (1) is not activated.
If (1) is in operation, reset it (step). Therefore, even if there is no knock pulse in the first period, if a knock pulse is input within the time set by the timer (1), the timer (1) is reset.
Gradual decrease control of the retard amount θ(I) is not performed.

In addition, when the ignition timing retard amount θ(I) is determined in the steps above, does the retard amount θ(I) exceed the maximum retard amount θ _MAX that the engine can allow in relation to the exhaust temperature? If it does not exceed it, it remains as is, and if it does, it is fixed at θ _MAX (step, 〓〓) and output.

Next, when it is determined by the counter T2 in step that the second period, that is, 16Ig, has passed, this counter T2 is reset (step 〓〓) and the number of waste gate control flags WF counted in the previous step is set. The duty of the duty solenoid valve 20 is determined accordingly. That is,
When the above WF is 4, 3, 2, 1, the duty is 0.
%, 25%, 50%, and 75%. Otherwise, the duty is not changed. Furthermore, when WF is 3, 2, and 1, check whether the current duty is smaller than the duty to be controlled. The duty is controlled only when it is negative (large) (steps 〓〓〓 to 〓〓). Therefore, once the supercharging pressure is reduced by duty control, the supercharging pressure is not increased until the ignition is turned off.

Then, if the duty is controlled to be lowered after passing through the duty processing section,
The timer (2) is activated, and after the set time T _RST has elapsed, the retard amount θ(I) is controlled to zero (reset), and the timer (2) is further reset (steps 〓〓〓 to 〓〓). . In other words, the ignition timing is reset only when the boost pressure is lowered, and when it is not the case (when no knocking occurs 4 times during 4Ig,
When the boost pressure is fixed at the minimum <duty 0%>), retard control of the ignition timing is maintained. Now, an example of control by the engine control device is shown in a time chart in FIG. 4.

That is, in the case of the illustrated example, the knock pulse is applied once each in the first period (4Ig) of the second and third times,
During the fourth first period, knock pulses occur three times, and each time the ignition timing is retarded by a crank angle proportional to the number of knock pulses. And the first period of these four times, that is, the second period (16Ig)
Since the number of times 4 knock pulses occur during 4Ig is zero, the wastegate control flag is
WF does not rise, boost pressure is not reduced, and duty remains at 100%. Therefore, the ignition timing retard is not reset even after the second period has elapsed.

Then, in the second period, the first 4Ig
There are four knock pulses in between, and the ignition timing is further retarded in response to this second knock pulse.
After a period of , the supercharging pressure is controlled to decrease (75% duty), and then the ignition timing retard is reset. Then, in the second period of the third time, there is one time (WF = 1) where four knock pulses occur between 4Ig, and the ignition timing is retarded accordingly, but the current duty is 75%.
Therefore, the duty is maintained at 75% by the processing in steps 〓〓 and 〓〓 of the previous flow, and there is no control to lower the supercharging pressure.

Next, in the second period of the fifth time, a knock pulse is generated and the ignition timing is further retarded, but since only one WF stands, there is no control to lower the supercharging pressure. Then, in the second period of the sixth time, the ignition timing is further retarded due to the continuous occurrence of four knock pulses during 4Ig, but the retard amount θ(I) is fixed at θ _MAX when it reaches θ _MAX , and no further retardation is performed. Therefore, an excessive rise in engine exhaust temperature is prevented. Then, in this 6th second period, 4
WF is standing, the duty is set to 0%, the boost pressure is in the minimum state (the boost pressure corresponding to the use of regular fuel), and from then on, the boost pressure is not controlled to decrease, and the ignition There is no increase in supercharging pressure until the engine is turned off. In other words, the boost pressure is fixed at the minimum state. The ignition timing retard is then reset.

Therefore, after the above-mentioned boost pressure is fixed, knocking can be eliminated only by retard control of the ignition timing, and after the retardation of the ignition timing, no knock pulses must be input until the time set by the timer (1) (T = 200ms) has elapsed. For example, the retard amount θ(I) is decreased by 0.2 degrees, and if there is no knock pulse thereafter, θ(I) is decreased by 0.2 degrees at every set time T until it becomes zero.

As described above, according to the above-mentioned engine control device, since the retard control of the ignition timing is performed based on the short-term occurrence of knocking, it is possible to eliminate the knocking with good responsiveness, and the long-term occurrence of knocking can be eliminated. Since the boost pressure is controlled based on the above, the control accuracy of the boost pressure is increased. Moreover, the timing of retard control and boost pressure control is different, which prevents hunting in the control, making it easier for the retard amount and boost pressure to settle to the values required by the engine, resulting in fluctuations in engine output. can be suppressed.

In the case of the above embodiment, since the retard amount and boost pressure are controlled according to the frequency rather than the magnitude of knocking, large noise is generated.
There is no large retard in ignition timing or large drop in boost pressure even if the engine is turned on, increasing reliability against noise.

Furthermore, since the retard of the ignition timing is reset when controlling the boost pressure to decrease, an excessive decrease in engine output is prevented.

Additionally, once the boost pressure is lowered, it will not rise until the ignition is turned off, which prevents the boost pressure from fluctuating up and down during transient periods when the engine is likely to knock, improving operational stability. It increases.

In addition, since the retard of the ignition timing is gradually reduced if there is no knocking, the ignition timing is settled near the critical point of whether or not knocking occurs, thereby preventing a rise in engine exhaust temperature and maintaining output.

Note that the retard and boost pressure may be controlled based on the magnitude of knocking rather than the frequency of knocking, and the first and second periods may be changed as appropriate depending on the type or characteristics of the engine. I can do it.

In addition, in the above embodiment, the amount of decrease in boost pressure is determined according to the number of WFs based on the initially set boost pressure, but each time WF rises, the WF decreases based on the previous boost pressure. A method may be adopted in which the amount of reduction in supercharging pressure is determined according to the number of fuels (WF is integrated).

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is an overall configuration diagram of an engine control device, Fig. 2 is a block diagram of a control system, Fig. 3 is a control flow diagram, and Fig. 4 is an example of a control mode. FIG. DESCRIPTION OF SYMBOLS 1... Engine body, 4... Supercharger, 8... Intake passage, 12... Exhaust passage, 17... Waste gate valve, 20... Duty solenoid valve, 21
...Knock sensor, 23...Spark plug, 24...
...Distributor, 25...Controller.

Claims (1)

[Claims] 1. In an engine equipped with a supercharger, an ignition timing adjustment means for adjusting the ignition timing of the engine;
A boost pressure adjusting means for adjusting boost pressure by the supercharger; a knock sensor for detecting engine knocking; ignition timing control means for outputting an ignition timing control signal to the ignition timing adjustment means to determine an amount of retard of the ignition timing, retard the ignition timing, and gradually reduce the amount of retardation of the ignition timing when the knocking is not detected; When knocking is detected in response to the output of the knock sensor during the second period, which is longer than the first period, the amount of reduction in the boost pressure is determined according to the output of the knock sensor, and the above-mentioned supercharging is performed so as to reduce the boost pressure. A supercharging pressure control means outputs a supercharging pressure control signal to the pressure regulating means, and upon receiving a supercharging pressure reduction control signal from the supercharging pressure control means, the retard amount of the ignition timing at that time is determined from the gradual reduction rate of the retard amount. 1. A control device for an engine, comprising: forced retard amount reduction means for outputting a retard amount reduction signal to the ignition timing control means so as to quickly reduce the amount of retard.