JPH0256515B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a knock suppression system for detecting knocking in an internal combustion engine and controlling at least one operating characteristic of the engine.

Notsking is the ignition timing among the operating characteristics of the engine.
It occurs depending on many factors such as air-fuel ratio, intake air temperature, intake air humidity, and combustion chamber temperature. Of these factors, ignition timing and air-fuel ratio are relatively easy to control and can be controlled at low cost, so they can be used as a means of feedback control to suppress knocking. In particular, there are many knocking suppression devices that use ignition timing control. It has been put into practical use.

By the way, in conventional knocking suppression devices using ignition timing control, which have been put into practical use, the ignition timing is retarded from a preset standard ignition timing by a fixed angle or by an angle corresponding to the knocking intensity each time knocking occurs. If there is no occurrence of
Feedback control is performed by controlling the ignition timing to the knock limit.

However, in the above control, a wide dynamic range is required because all operating ranges, including the small ignition timing correction range that requires knock control and the large ignition timing correction range, are controlled by changes in the magnitude of the feedback control amount. Therefore, it was difficult to control accurately over all operating ranges.
In addition, when the operating state of the engine changes, the feedback control amount is the control amount for the previous operating state, and has no meaning in the operating state after the change. There will be a large time lag before the transition.
That is, there was a drawback in that control responsiveness to changes in operating conditions was poor.

As mentioned above, the occurrence of knocking is influenced by many factors, such as intake air temperature and intake air humidity, which depend on changes in natural conditions, and the cycle of these changes varies over the course of a day or season. It is a very long time that can be considered as a unit.
Therefore, changes in the knocking occurrence situation due to these changes also have a long cycle. Conversely, the knocking that occurs in a short period of time under the same operating conditions is approximately the same level, and there is no significant difference in the frequency and intensity of the knocking.
In other words, the control amount required to suppress knocking that occurs under the same operating condition is almost the same in a short period of time, so in the same operating condition (mode) of the engine specified by specific operating parameters, the previous control amount is The memorized control amount is used as the current control amount, and the correction range can be narrow in case of slight knocking during control. Knocking can be suppressed with good responsiveness and high precision. Furthermore, the aforementioned long-term change factors can be corrected by slowly changing the storage control amount.

However, knocking has statistical properties, and for example, if the engine is ignited at an advance angle that exceeds the knock limit, knocking will occur over unit time or the number of engine ignitions depending on the amount of advance. The distribution of occurrence frequency shifts to the increasing side, and the distribution of knocking intensity shifts to the increasing side. In general, it is considered desirable to control the engine so that it is operated near the knocking limit in consideration of engine damage caused by knocking, engine efficiency, and the like. However, due to the above-mentioned statistical properties of knocking, the frequency of knocking occurring near the knocking limit is very low, so if the above memory control amount is updated in a short time, the original memory control amount will reach the knocking limit. Even if knocking does not happen to occur in the update cycle, the storage control amount is updated to decrease (updated in the direction in which knocking occurs). Since the subsequent knocking suppression control is started using the memory control amount that has been decreased and updated, large knocking or continuous knocking will occur, and the memory control amount will be updated again in the direction of knocking suppression, resulting in the knocking suppression control amount. There is a fluctuation in the
For example, in ignition timing control, variations in ignition timing occur. On the other hand, if the memory control amount is updated at a very long period so that it is sufficiently recognized that it is at the notching limit, for example, the memory control amount is insufficient and the amount greatly exceeds the notching limit. If the control amount is insufficient, the insufficient amount should be updated immediately and the average control amount should be set to the knock limit, but because the update cycle is long, the engine operating state (mode ) has been transferred to another location, and the storage control amount is not updated. Therefore, when the engine returns to the operating state again, large knocking occurs and its suppression is successively corrected, and the stored control amount is updated only after the update cycle.

The present invention has been made in consideration of the above points, and includes feedback control that detects knocking occurring in the engine and generates a control signal in response to this detection output to suppress knocking. A storage area corresponding to each state is provided, and the average control amount for each operating state of the engine is stored in the corresponding storage area, and when knocking occurs, the control amount is stored in accordance with the average control amount stored above and the strength of the knocking that has occurred. By sequentially performing knock control every time knocking occurs using a small amount of control, it is possible to suppress knocking accurately and with good responsiveness. When knocking occurs, the average control amount that is already stored is quickly updated at a predetermined period in the direction of suppressing knocking, and when there is no knocking, the average control amount is changed in the opposite direction. By controlling the engine to update and change at a predetermined period different from the above-mentioned period, it is possible to eliminate the time lag of knock suppression control when the operating state of the engine changes, and improve the responsiveness of knock suppression in all operating states. It is an object of the present invention to provide a knock suppressing device for an internal combustion engine that can perform precise control.

Embodiments of the present invention will be described below with reference to the drawings. Note that there are many factors that cause knocking, and knocking can be suppressed by controlling any of them, but in this embodiment, the case of ignition timing control, which is the most commonly used ignition timing control, will be explained.

FIG. 1 shows the basic configuration, and the storage means 3 stores information in the corresponding area based on the engine load state detected by the load detection means 1 and the engine rotation speed detected by the rotation speed detection means 2. The control amount is read out and sent to the control amount calculation means 4. The control amount calculation means 4 calculates a knock suppression control amount from the control amount sent from the storage means 3 and the knocking signal detected by the knock detection means 5, and controls the actuator 6. Furthermore, when the engine operation calculation satisfies a predetermined determination condition, the storage means 3 increases or decreases the stored control amount at different predetermined cycles depending on the presence or absence of a detection signal from the knock detection means 5.

Fig. 2 shows the specific configuration of this embodiment, where 11 is a crank angle sensor that generates a reference crank angle signal according to the rotation of the engine, and 12 is a crank angle sensor that detects the intake pipe pressure of the engine and outputs a pressure signal corresponding to its output. 13 is a first A/D converter that digitizes the pressure signal output from the pressure sensor 12 according to its level; 14 is attached to the engine;
Acceleration sensor for detecting engine vibration acceleration, 15
16 is a knock detector 15 which discriminates a knocking component generated due to knocking of the engine from the detection output of the acceleration sensor 14 and outputs a knocking signal of a level corresponding to the knocking intensity.
A second A/D converter digitizes the output signal of the second A/D converter. 20 is a microcomputer;
Mainly microprocessor (central processing unit) 21
, a memory (storage device) 22, and an interface (input/output signal processing device) 23. 17 is an ignition coil controlled by the microcomputer 20.

Next, the operation of the above device will be explained. The crank angle sensor 11 detects the rotation angle position of the engine once per ignition cycle as the engine rotates, and outputs a crank reference angle pulse, and this output is input to the interface 23. The pressure sensor 12 detects the intake pipe pressure of the engine and generates a pressure signal at a level corresponding to that pressure. Since the intake pipe pressure of the engine changes in response to the load condition of the engine, the load condition of the engine can be determined from the level of the pressure signal. This pressure signal is digitized by the A/D converter 13 and input to the interface 23. On the other hand, the acceleration sensor 14 is attached to the engine and constantly detects vibrations of the engine. This detection output includes a knocking component due to vibration generated due to knocking superimposed on a noise signal due to engine noise generated by engine operation. The knock detector 15 discriminates the knocking component from the detection output of the acceleration sensor 14, and outputs a knocking signal having a level corresponding to the knocking intensity. This knocking signal is digitized by the A/D converter 16 and input to the interface 23. Also,
The knock detector 15 is reset by the interface 23 under the command of the microprocessor 21 and initialized for knocking detection.

The memory 22 of the microcomputer 20 is
It has a ROM and a RAM, and the ROM stores the reference ignition advance angle in each operation mode of the engine corresponding to each address at each predetermined address corresponding to the engine speed and engine load condition. The RAM has an area (hereinafter referred to as an advance angle map) in which the advance angle map is used to store the notches for each operating mode of the engine corresponding to each address at each predetermined address corresponding to the engine speed and load condition. It has an area (hereinafter referred to as a learning map) for storing each average control amount calculated based on the output of the detector 15. The microcomputer 20 calculates the knock control amount from each sensor information of the crank angle sensor 11, the pressure sensor 12, and the acceleration sensor 14, calculates the optimal ignition timing, and starts the ignition coil 1 at the determined ignition timing.
7 and ignite the engine. Further, the microcomputer 20 starts processing for updating the average control amount for knock suppression when the operating state of the engine satisfies the following conditions, for example.

Condition 1: Rotation fluctuations from the start of the update process
50rpm or less condition 2 Load fluctuation from the start of the update process is 5%
If the engine is operated with the above two conditions satisfied for 10 consecutive ignition cycles, knocking occurs during that period, and the knocking suppression is successively corrected, in other words, the average control amount is insufficient. If so, the correction amount is sequentially added to the average control amount and stored in the corresponding area of the learning map as a new average control amount. As a result, the deficiency in the average control amount is promptly updated and increased. Also, the institutions are consecutive
If the engine is operated with the above two conditions satisfied over 200 ignition cycles, during which no knocking occurs and the sequential correction amount is zero, the current knock suppression control state is considered to be below the knock limit, and the average control amount is One unit control amount is subtracted from the average control amount and stored in the area of the learning map corresponding to the current operating state as a new average control amount. In this way, by updating the average control amount to decrease only when knocking does not occur over a relatively long period, it is possible to update the average control amount in the direction in which knocking occurs in the region exceeding the knocking limit described above. This prevents fluctuations from occurring in the knock suppression control amount. Once the average control amount for knock suppression is updated in this way, sequential knock control is started based on the updated average control amount. In other words, the average control amount is updated so that the sequential correction amount is minimized, and ignition is performed at the optimal ignition timing. Suppose now that the operating state of the engine has changed and the engine has moved to another operating state. Assuming that the average control amount is already stored in the learning map at a position corresponding to the changed operating state, knock suppression control is sequentially started based on the changed average control amount. In other words, unlike conventional devices, control does not start from the knock suppression control amount before the operating state changes, but immediately enters a control state based on the average control amount that has already been obtained, so the responsiveness of knock suppression control is significantly improved. improves. Further, due to conditions 1 and 2, the average control amount stored in the learning map is not updated in transient states of changes in driving conditions such as acceleration and deceleration. Therefore, the knock suppression control amount (sequential correction amount) created by knocking that occurs during a transient state of engine operation is not used to update the average control amount, and is meaningless (the storage of information that does not correspond to the

The flowchart for executing the above control is shown in the third section.
As shown in the figure. _P1 to _P26 indicate each step. The control calculation is executed, for example, once per ignition cycle when a crank reference angle pulse is input. First, input the crank reference angle pulse at _P2 , and calculate the period from the previous crank reference angle pulse at _P3 , and convert it to the number of revolutions. Input the pressure signal in P ₄ , and calculate the engine load condition in P ₅ . At _P6 , the set advance angle corresponding to the rotational speed and load condition calculated at _P3 and _P5 is retrieved from the advance angle map and stored in the A register.
At _P7 , similarly to _P6 , the average control amount for knock suppression corresponding to the rotational speed and load condition is searched from the learning map and stored in the B register. A knock signal is input at _P8 , and a signal for resetting the knock detector 15 is generated at _P9 to prepare for detecting the next occurrence of knocking. At _P10 , a control correction amount corresponding to the intensity of the knocking signal input at _P8 is calculated, added to the previous sequential correction amount stored in the C register, and stored in the C register again.

Next, at P ₁₁ and P ₁₂ , the rotation speed fluctuation is 50 rpm or less (condition 1) and the load fluctuation is 5% or less (condition 2).
Check whether If condition 1 or condition 2 is not satisfied, set the value of the D register to zero in P ₂₂ , and P ₂₃
Then, the meaningless correction amount C before the change in the operating state is set to zero, and the process moves to _P24 . The D register is a register for counting the number of ignitions used to determine the update cycle of the average control amount. If both conditions 1 and 2 are satisfied, 1 is added to the value stored in the D register at _P13 , and the value is stored in the D register. next,
At _P14 , check whether the content stored in the D register is 10. That is, it is checked whether conditions 1 and 2 are satisfied and 10 ignition cycles have elapsed. D
If the contents of the register are less than 10, the process moves to _P24 , and if the contents are 10 or more, it is checked in _P15 whether the sequential correction amount stored in the C register is zero. C
If the contents of the register are not zero, that is, knocking has occurred, the contents of the C register are added to the contents of the B register in _P16 , and the result is stored in the B register.
At _P17 , the contents of the C register storing the sequential correction amount are set to zero. If C=0, that is, no knocking occurs, it is checked in _P18 whether the contents of the D register are 200 or not. That is, it is checked whether conditions 1 and 2 are satisfied and a state in which no knocking occurs has continued for 200 ignition cycles. If there are less than 200 ignition cycles, proceed to P ₂₄ processing. When 200 ignition cycles have been reached, in _P19 the average control amount found by searching the learning map in _P7 is subtracted by one unit amount from the contents of the B register temporarily stored and stored in the B register again. Next, in _P20 , the stored value of the B register changed in _P16 or _P19 is stored as a new average control amount in the area of the learning map corresponding to the current engine operating state. At _P21 , the contents of the D register are zeroed in preparation for the next update of the learning map. In P ₂₄ , search from the lead angle map in P ₆ and find A
The set advance angle stored in the register and the average control amount stored in the B register (updated average control amount if the process of P ₁₅ to _{P 21} is passed)
The ignition advance angle is determined from this and the sequential correction amount stored in the C register, and after outputting the ignition advance angle to the output register at _P25 , the program moves to the next control program at _P26 .

When the rotation angle of the engine reaches a position corresponding to the ignition advance angle outputted to the output register, the interface 23 cuts off the current flowing through the ignition coil 17, and the engine is ignited.

Here, if the engine is continuously operated with Conditions 1 and 2 satisfied and knocking does not occur over 200 ignition cycles, the average control amount decreases by 1 unit as shown from P ₁₃ onwards. Therefore, if the engine is continuously operated under the same conditions, the average controlled amount will be
It continues to decrease every 200 ignition cycles and finally reaches a negative value. In other words, ignition is performed at a more advanced angle than a preset ignition advance angle (stored in the advance angle map).

As mentioned above, in the conventional knock suppressing device, knocking is suppressed by controlling the amount of retardation from a set ignition advance angle, that is, by unidirectional control. It is possible to control the ignition advance angle to either advance or retard. Therefore, as data for the advance angle map that stores the ignition advance angle, the ignition advance angle determined as the optimal value at the time of engine design is stored as the memorized value, and furthermore, the entire area of the learning map that stores the average control amount is used. By storing zero as the initial value, the initial knock suppression control is started based on the engine design value, and the knocking caused by individual engine variations and seasonal changes is corrected using the average control amount. Unlike conventional devices, there is no need to anticipate and set the control range for knock suppression in advance, and initial controllability is also greatly improved.

By the way, there are many factors that cause knocking, but among them, air-fuel ratio control using ignition timing control or fuel control as in this embodiment is desirable. This is because many devices related to ignition timing control and air-fuel ratio control have been put into practical use and are not only easy to implement, but also can be implemented at low cost.
In the case of air-fuel ratio control, the same function as the present embodiment can be achieved by increasing the injection amount from the fuel injection device in accordance with a control signal that is a knocking signal.

As described above, in the present invention, the feedback control system detects knocking occurring in the engine, generates a control signal in response to the detection output, and suppresses knocking in response to the engine speed and load condition. A storage area is provided, and the average control amount for knock suppression in each operating state of the engine is stored in the corresponding storage area.When the engine is running, the corresponding average control amount is read from the storage area, and based on this average control amount. Knocking generation elements are controlled, and knocking suppression control is performed by sequentially adding correction amounts to the average control amount for slight knocking that occurs during control, and knocking suppression is performed with good responsiveness. be exposed. In addition, if a sequential correction is made due to the occurrence of knocking, this sequential correction amount is added to the average control amount in the first predetermined cycle, and if no knocking occurs and the sequential correction amount is zero, the average control amount is By reducing the control amount by a predetermined amount in a second predetermined period that is longer than the first predetermined period and storing it in the corresponding storage area and updating the average control amount, it is possible to respond to long-period changes in the factors that cause knocks. In addition, even when the operating state of the engine changes, the influence of the meaningless knock suppression control amount before and during the change is removed, eliminating the time lag of knock suppression and improving the responsiveness of knock suppression. This is a significant improvement, and it is possible to always perform appropriate knock suppression over the entire operating range. In particular, since updating of the control amount in the direction of knock suppression is performed at a long update cycle after the engine is in a stable state, unnecessary knocking can be prevented from occurring.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the device of the present invention, FIG. 2 is a specific configuration diagram of the device of the present invention, and FIG. 3 is a flowchart for explaining the operation of the device of the present invention. 1...Load detection means, 2...Rotation speed detection means,
3... Storage means, 4... Controlled amount calculation means, 5...
Knock detection means, 6...actuator.

Claims (1)

[Claims] 1. Knock detection means for detecting knocking of the engine, load detection means for detecting the load condition of the engine, rotation speed detection means for detecting the engine rotation speed, and each predetermined address corresponding to the engine load and rotation speed. The control amount calculated based on the output of the knock detection means in each operation mode of the engine corresponding to each address is stored, and the corresponding address is stored based on the output of the load detection means and the output of the rotation speed detection means. A memory means from which a value is read out, and a control variable for controlling at least one operating characteristic quantity of the engine is corrected using the read control variable and a sequential correction amount according to the output of the knock detection means. means of controlling knotking;
When knocking is occurring, the stored value of the address of the memory means corresponding to the operating mode at the time of processing is updated to a value in the direction of suppressing knocking on the condition that the operating state of the engine is in a steady state for a predetermined period of time. 1. A knock suppressing device for an internal combustion engine, characterized in that the knock suppressing device for an internal combustion engine is provided with an updating means for updating a value in the opposite direction when the operating state of the engine is in a steady state for a predetermined period longer than the predetermined period.