JPS63124866A - Knocking control device for engine - Google Patents

Abstract

PURPOSE:To prevent an overcontrol of knocking, by equipping an engine with a means, which sets its combustion condition, and setting a peak value, measured by a vibration sensor when the engine is placed in a condition that no knocking is generated, to a decision level. CONSTITUTION:A knocking control means 101 performs a control of preventing knocking when an output value from a vibration sensor 100 is larger than a decision level set by a decision level setting means 102. Here the decision level is a peak value measured by the vibration sensor 100 when a combustion condition, set by a combustion condition setting means 103, is the condition that no knocking is generated. In this way, the knocking control can be performed in good accuracy with no generation of knocking corresponding to unevenness and aging deterioration or the like of the vibration sensor 100.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an engine knock control device, and particularly to an engine knock control device that performs knock prevention control when engine vibration exceeds a predetermined determination level. It is.

(Prior art) Before the flame propagates after ignition in the combustion chamber, unburned mixed gas spontaneously ignites and causes rapid combustion, usually at a frequency of 5 KHz to 10 KHz.
The occurrence of interference waves of KHz frequency components is called knocking. One way to prevent this knocking is to install a vibration sensor outside the combustion chamber of the engine, and when the vibration exceeds a predetermined determination level, the system increases the
Alternatively, the ignition timing is delayed to lower the combustion temperature and prevent knocking.

For example, in Japanese Patent Laid-Open No. 56-47663, the occurrence of knocking is prevented by delaying the ignition timing. Furthermore, a processing method when an abnormality occurs in the vibration sensor is described.

By the way, conventionally, the determination level of vibration when controlling knocking is a value obtained by multiplying the average value of the vibration output from the vibration sensor by a constant. In this case, if the determination level is too low, knocking will be over-controlled, so it is set high, and knocking will be incompletely prevented. Furthermore, it is not easy to change the settings due to variations in the vibration sensor or changes over time, which causes a great deal of inconvenience. Furthermore, if knocking occurs before the determination level is set, it will place a large burden on the engine.

(Problems to be Solved by the Invention) The present invention eliminates the drawbacks of the conventional example and over-controls the occurrence of knocking in response to various conditions such as variations in vibration sensors without causing knocking. To provide an engine knocking control device that accurately prevents engine knocking.

(Means for Solving the Problem) As a means for solving this problem, an embodiment of the engine knocking control device of the present invention shown in FIG. A vibration sensor 100 for measuring, a knocking control means 101 for controlling the engine to prevent knocking when the vibration measured by the vibration sensor 100 exceeds a predetermined determination level, and a knocking control means 101 for controlling the engine such as fuel injection amount and ignition timing. combustion condition setting means 103 for setting combustion conditions; and judgment level setting means 102 for setting the peak value of vibration input from the vibration sensor 100 as the judgment level when the combustion conditions are such that knocking does not occur.

(Function) In this configuration, the knocking control means 101 sets the output value from the vibration sensor 100 to the determination level setting means 102.
Knocking prevention control is performed when the determination level is higher than the set determination level, and this determination level is set by the determination level setting means 102 to determine whether the combustion conditions set by the combustion condition setting means 103 are conditions in which knocking cannot occur. This is the peak value of the output value of the vibration sensor 100.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

First, the features of this embodiment will be clarified by comparing the conventional knock detection circuit shown in FIG. 8 with the circuit shown in FIG. 2 in which knock detection corresponds to the conventional example.

In Fig. 8, vibrations at a frequency related to knocking, for example, 5 KHz to 10 KHz, are extracted from the output of a vibration sensor from a vibration source using a band pass filter (BPF), and are averaged by being delayed by an RC circuit. Then, the determination level is determined by multiplying it by a gain set according to the engine rotational speed, and is compared with the output of the vibration sensor to determine the knock detection output.

On the other hand, in FIG. 2, a bandpass filter (BP
The peak value of the output from F) is held by a peak hold circuit, and this peak value is selected by a judgment level setting circuit under predetermined conditions and set as a judgment level. Other operations are similar. As described above, the feature of this embodiment lies in the method of setting the determination level.

Figure 's3 is a specific configuration diagram of the engine and the engine knocking control device of this embodiment. Note that, for the sake of simplicity, the intake air temperature sensor, cooling water temperature sensor, etc. that are not directly related to the features of this embodiment are omitted. In this embodiment, knocking is controlled by an engine control unit (ECLI).

1 is an air flow meter that measures the amount of intake air Qa; 2 is an injector that injects fuel by an injection amount TL; 3 is an ignition coil that generates a high voltage at the ignition timing Ig;
4 is a distributor that sends high voltage from the ignition coil 3 to the spark plug 9; 4a is a rotation speed meter that measures the engine rotation speed Ne; 5 is a vibration sensor that measures vibrations in the combustion chamber 6 of the engine; 6 is a combustion sensor 7 is an engine control unit (ECU), 8 is a throttle valve linked to the accelerator, and 9 is a spark plug.

The ECUT calculates the fuel injection amount Ti and the ignition timing 1g based on the intake air amount Qa from the air flow meter 1 and the engine rotation speed Ne from the rotation speed meter 4a. in fact,
Intake air temperature, throttle valve opening, cooling water temperature, not shown
Although it is corrected by inputting the oxygen concentration in the exhaust gas, etc., it is excluded in this example for the sake of simplicity. Air conditioner control and alternator power generation control are also performed as output, but details are not included here. In this embodiment, the ECU 7 is the combustion chamber 6 of the engine.
Effective control to prevent knocking is performed based on the vibration value P from the vibration sensor 5 installed outside.

FIG. 4 shows a configuration diagram of the ECU 7. 71 is CPLI
, 72 is a timer that sends the ignition timing Ig to the ignition circuit 30 such as the ignition coil 3 shown in FIG. The ROM 75 stores the procedure and various constants, the intake air amount Qa from the air flow meter, the rotation speed Ne from the rotation speed meter, and the vibration from the vibration sensor! ! ] An A/D converter 76 converts an analog input value such as the peak value Pk of P into a digital value, and 76 is an input circuit that takes out the peak value Pk of the vibration P from the vibration sensor.

FIGS. 5(a) and 5(b) show flowcharts of determination level learning by the ECU 7.

First, an interrupt occurs when the learning condition is met, that is, when the engine continues to operate steadily for a predetermined period of time under the same operating state (usually divided into zones such as feedback zone, enrichment zone, etc.). Figure 5 (a
) flow. In step S50, during learning, the ignition timing is delayed and the engine is operated in an overrich state, so in order to compensate for the output loss, alternator power generation is stopped and when the air conditioner is used, it is stopped. Next, in step S51, R
Ignition timing retard 1R during learning stored in OM74
tt and the fuel increase Af are set as the retardation amount Crat in the RAM 73.
and read out the fuel increase it CA r.

Here, the ignition timing Ig is Ig=IgO+Ck+C,
t, the fuel injection pulse width Ti is Ti=TpXC,XCA,
Igo is the basic ignition timing, CK is the retardation amount during knock control, ``rp is the basic fuel injection pulse, and C7 is a collection of various correction coefficients.In step S51, the retardation amount Crat and Since the predetermined value has been read out for the fuel increase amount CAf, the engine operates more retarded and richer.

In step S52, the down counter C2 in the timer 72
and a predetermined number is set in C2. Here, the number of the counter C1 is set to the time it takes for the engine to reach a stable operating state after being made overrich on the retard side in step S51.
The number of counter C2 sets the number of times of learning. therefore,
The condition is C,<C2. Further, in step S52, the knocking control retardation amount Ck is set to "0" and the process returns.

Next, when an interrupt occurs at TDC (Top Dead Center), other controls not shown are also performed, but if the learning condition is satisfied and after passing through FIG. 5(a), as shown in FIG. Enter the flow of b). Therefore, the flowchart in FIG. 5(b) is an extracted portion of the flowchart related to this embodiment.

First, in step S60, the peak value Pk of the vibration P from the vibration sensor input from the input circuit 76 is input and read into Ad in the RAM 73. Step S6
1 outputs a reset pulse to reset the peak hold circuit in the input circuit 76. In step S62, it is checked whether the operating state is the same as the previous zone. If you want to pass first, select YES. If the zone has changed due to a change in the operating state from the previous time, step S70
Proceed to and stop learning. If the zone is the same as the previous time, in step S63, step 352 in FIG. 5(a) is performed.
The counters C, , C2 set in are counted down by one, and in step S64 it is checked whether the counter C1 is 0''. If it is not 0, the process returns to wait for the engine to stabilize.

The engine is stable under the learning conditions and counter C8 is “0”.
', then in step S65 the counter C
Check whether 2 is 0”.When learning, counter C
Since 2 is not "0", the process advances to step S66, and in step S66, the determination level Le at the previous learning time is read out from the learning table shown in FIG. 5(C). Although the determination level Le is assigned in accordance with the engine rotation speed in this embodiment, the determination level Le is not limited to this. In step S67, the peak value P of the vibration sensor manually inputted in step 560 is
Ad for which k is set is compared with the previous judgment level Le, and if Ad > Le, the content of Ad is reduced to Le, and from the next time onwards, the peak value Pk input this time will be the value of Le. If Ad≦Le, Le remains unchanged. At step 569, Le is stored in the learning table and the process returns. The Le stored in the learning table is thereafter used as a determination level for performing knocking control corresponding to the rotation speed.

When the counter C2 becomes 0'' in step S65, the learning period has elapsed, so in step 370 the alternator power generation that was stopped in step S50 is started, and when the air conditioner is in use, the alternator power generation is started.
N, the retardation amount C,, t, and fuel increase CAP during learning are reset, and the learning is completed.

FIGS. 6(a) and (b) show FIG. 5(a).

As shown in (b), if all cylinders are set to the retard side during learning and set to rich, the output will be extremely reduced and fuel consumption will increase, so a flowchart is shown in which the learning is performed by setting only one cylinder to rich. In the case of a four-cylinder engine, by learning about two different cylinders in this way, it is possible to sufficiently control engine knocking.

First, in FIG. 6(a), only a predetermined cylinder, in this example, the #1 cylinder, is made rich. Similarly to FIG. 5(a), when the learning condition is satisfied, an interrupt occurs.

In step S80, the ignition timing of all cylinders is retarded, and #1
Make one cylinder rich and leave the other cylinders as they are or lean.

In step S81, the knocking control amount Ck l is set for all cylinders.
” CK a is set to “0”, counters C1 and C2 are set in the same manner as in FIG. 5(a), and the process returns.

The process shown in FIG. 6(b) is performed by an interrupt when the #1 cylinder reaches TDC (top dead center). First, step S9
0 resets the peak hold circuit of the input circuit 76. Thereafter, in step 591, wait until the predetermined crank angle is reached, and when the predetermined crank angle is reached, the peak value Pk of the vibration P of the vibration sensor up to the present after being reset in step S90 is stored in the RAM 73 as Adl, :t! ! I pay r. This is to detect vibrations only in the rich cylinder.

In Fig. 6(b), the timing at which knocking occurs is approximately at the 6th point.
Since it was between T1 and T2 shown in Figure (C), the measurement was limited to this period. The method of limiting the period is not limited to the flow of this example. From step S93 to step 5101,
The steps from step S62 to step S70 in FIG. 5(b) are the same and will not be repeated. In this example, all cylinders are shifted to the retard side and one cylinder is made rich, but this combination is not limited to this example and various other combinations can be considered.

In this way, the learned knocking judgment level is the peak value of the vibration generated by the engine that has been brought into a state where knocking does not occur by retarding the ignition timing or making it rich. The level is approximately the maximum level at which the occurrence of knocking can be detected before it occurs. A more accurate determination level can be set by changing the amount of movement to the retard side and the increase in fuel amount depending on the structure of the engine. Furthermore, since the determination level can be set without causing knocking, there is no burden on the engine.

Furthermore, in the above example, when the learning conditions were met, learning was performed by moving to the retard side or increasing the amount of fuel to create a state in which knocking did not occur. It also helps to start.

In FIG. 7, an interrupt occurs when the engine has been in a steady state for a predetermined period of time, and the ignition timing Ig is first set to a stable predetermined value a at which knocking does not occur in step 5ilo.
Check if it is between l and 82, step 5111
The fuel injection amount Ti is also set to a predetermined value b1 at which knocking does not occur.
and b2. If both are in a stable state, counters C1 and C2 are set in step 5112.
is set, and learning of the judgment level shown in FIG. 5(b) or FIG. 6(b) is performed. If either is out of stable condition, it will return without doing anything. In this way, there is no need to set aside any special learning time, and learning can be performed automatically when the engine operates stably for a predetermined period of time during normal driving.

In this embodiment, the TJffij to the retard side and the enrichment were performed at the same time, but this may be controlled by only one of them. In addition, the technical merit of the present invention is to accurately create control variables in which it is disadvantageous to measure the limit value once they have occurred, such as knocking, in response to changes in conditions. It can also be applied to the creation of control variables.

(Effects of the Invention) According to the present invention, the mensin mechanism can be used to accurately prevent knocking without over-controlling the occurrence of knocking in response to various conditions such as variations in vibration sensors and changes over time. A knock control device can be provided.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of the engine knocking control device of this embodiment, Fig. 2 is a side view of the knock detection circuit of the engine knocking control device of this embodiment, and Fig. 3 is a diagram of the engine of this embodiment and the engine. A specific configuration diagram of the knocking control device. Figure 4 is a configuration diagram of the engine control unit of this embodiment. Figures 5 (a) and (b) are creation of judgment levels for the engine knocking control device of this embodiment. FIG. 5(c) is a learning table diagram used for creating a determination level. FIGS. 6(a) and (b) are other flowcharts for creating a determination level for the engine knocking control device of this embodiment. , Fig. 6(C) is a diagram explaining the timing of creating the judgment level in Fig. 6(b), Fig. 7 is a flowchart for creating the judgment level during normal driving, and Fig. 8 shows the knocking control amount M of the conventional engine. FIG. 3 is a side view of the knock detection circuit of FIG. In the figure, 1... Air flow meter, 2... Injector, 3... Ignition coil, 4... Distributor, 4a... Rotation speed meter, 5... Vibration sensor, 6... Combustion chamber, 7...ECU, 8...throttle valve, 9...spark plug, 71...CPLJ
, 72...Timer, 73...RAM, 74...R
OM, 75...A/D converter, 76...input circuit,
100... Vibration sensor, 101... Knocking control means, 102... Judgment level setting means, 103...
This is combustion condition setting means. (Yo2t・2・de−゛7′ Figure 5 (G) Figure 5 (S

Claims (4)

[Claims] (1) A vibration sensor that measures vibrations generated in the combustion chamber of an engine; and a knocking control means that controls the engine to prevent knocking when the vibrations measured by the vibration sensor exceed a predetermined determination level. , a combustion condition setting means for setting a combustion condition of the engine; and when the combustion condition set by the combustion condition setting means is a condition in which knocking does not occur, a peak value of vibration measured by the vibration sensor is set as the determination level. A knocking control device for an engine, comprising: determination level setting means. (2) The combustion condition setting means sets a predetermined fuel injection amount and a predetermined ignition timing when the engine continues steady operation for a predetermined period of time, and the determination level setting means sets a predetermined fuel injection amount and a predetermined ignition timing. 2. The engine knocking control device according to claim 1, wherein the determination level is set to a peak value of engine vibration when the ignition timing is set. (3) The combustion condition setting means sets the fuel injection amount and ignition timing from the intake air amount, engine rotation speed, etc., and the determination level setting means determines when the fuel injection amount and ignition timing are within a predetermined range. 2. The engine knocking control device according to claim 1, wherein the determination level is set to a peak value of engine vibration. (4) The engine knocking control device according to claim 1, wherein the determination level setting means sets a peak value of engine vibration during a predetermined crank angle after top dead center as the determination level.