JPH0641151Y2 - Knocking detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a technique for detecting occurrence of engine knocking.

[Prior Art] Conventionally, the technology for detecting knocking of the engine from the output of the knock sensor as shown in FIG. 4 has been as follows.

(I) From the output of the knock sensor, calibrate the value of each waveform peak for one ignition (annealed value) Vm, and after the ignition cycle, integrate (or anneal) the sensor waveform of that time. Ask.

(Ii) The smoothed value Vm is further calculated for each ignition by a predetermined smoothing coefficient (“16” in this case) according to the following equation (1) to obtain a smoothed value Vmean for multiple ignitions. .

Vmean = Vmean × 15/16 + Vm × 1/16 (1) (iii) Based on the smoothed value Vmean, the determination level Vref is calculated by the following equation (2).

Vref = Vmean × K + Vof (2) K ... constant Vof ... offset (constant) (iv) The above judgment level Vref is compared with the output of the knock sensor, and when the output of the knock sensor is larger, the engine is knocked. Judge that it has occurred.

In addition, as a technique for improving the knocking determination accuracy, when the knocking is determined, a technique for increasing the averaging coefficient is provided (Nippon Denso Koho Giho, date of issue January 15, 1985).
Sun, reference number 39-052), a technology to prevent the knock sensor output value from being used in the operation of the smoothed value Vmean when the number of times the knock sensor output value exceeds the judgment level Vref exceeds a predetermined value. (See Japanese Laid-Open Patent Publication No. 60-230565), a technique (see Japanese Laid-Open Patent Publication No. 60-123746) for increasing the rounding coefficient as the engine speed Ne becomes higher.

[Problems to be solved by the invention] However, the output value of the knock sensor is, as shown in FIG. 5, at the time of each ignition, even if knocking does not occur, when the engine speed or load is suddenly changed due to racing or the like. The output level changes greatly, and in the conventional technology, it is judged that knocking has occurred even though knocking has not actually occurred, or conversely, the judgment level has become too large and knocking has actually occurred. However, it was sometimes determined that knocking did not occur.

This is because the smoothed value Vmean, which is the basis for calculating the determination level Vref in the conventional technique, is the variation in combustion,
Since the effect of eliminating electrical noise is the main, even by the technique of simply annealing and improving the technique,
This is because the output level of the knock sensor is greatly affected by the value before the change and does not reflect the current operating state.

For example, in the former technique of increasing the smoothing coefficient when knocking is judged and the technique of controlling by the number of times the output value exceeds the judgment level Vref, it is possible to simply prevent the increase of the smoothed value Vmean due to occurrence of knocking. Yes,
The latter technology, which changes the smoothing constant depending on the engine speed, only causes the output value to fluctuate at high engine speeds.
Was not reflected in.

An object of the present invention is to improve the accuracy of detecting engine knock by solving the above problems.

[Means for Solving the Problems] As means for achieving the above object, the knocking detection device of the present invention is an engine as shown in FIG.
Knock sensor MB that detects the vibration of MA, and a predetermined smoothing coefficient that determines the weighting ratio of the weighted average value, the output of the knock sensor MB for each ignition,
A background value is obtained by performing a smoothing process, and a judgment level calculating means MC for calculating a knocking judgment level using this background value, and comparing the knocking judgment level with the output of the knock sensor MB, Knocking determination means MD for determining the occurrence of knocking, in a knocking detection device comprising: a transient operation time detection means ME for detecting the operating state of the engine MA and detecting a transient operation of the engine MA, At the time of the transient operation, the moderation coefficient of the determination level calculation means MC is corrected to a smaller one, and the transient operation correction means MF for increasing the ratio of the latest output of the knock sensor MB to the background value, It is characterized by including.

The transient operation is, for example, when the engine speed changes, when the intake air amount changes, when the fuel supply amount changes, or when the throttle opening changes.

[Operation] The knocking detection device of the present invention uses the output of the knock sensor MB as the judgment level calculation means MC when the transient operation is not performed.
According to (determines the weighting ratio of the weighted average value), the smoothing process is performed as it is by a predetermined smoothing coefficient to calculate the determination level, while the transient operation detecting means ME detects that the engine MA is in the transient operation. Occasionally, the determination level calculating means MC corrected by the transient correction means MF to a smaller one is used to smooth the output of the knock sensor MB to calculate the determination level, and the calculated determination level and the knock The output of the sensor MB is compared with the knocking determination means MD to determine the occurrence of knocking. As a result, during the transient operation, the determination level is calculated based on the output of the knock sensor MB that has been annealed with a smaller annealing coefficient than during the non-transient operation. That is, during the transient operation, the current output value of knock sensor MB is largely reflected in the calculation of the determination level. This improves the responsiveness and accuracy during transient operation.

[Embodiment] An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows a schematic configuration of a system to which this embodiment is applied, focusing on the engine 10.

The engine 10 is controlled by an engine controller 12. In the vicinity of the air cleaner 14, an intake air temperature sensor 16 that detects an intake air temperature and outputs an intake air temperature signal, and an intake air amount Q that detects an intake air amount Q are detected. An intake air amount sensor 17 that outputs a signal is provided.

At the downstream side of the air cleaner 14, the compressor 20 of the turbocharger 18 that supercharges the intake air, the compressor 20
Intercooler to cool intake air supercharged by
22 are provided.

A throttle valve 24 is arranged on the downstream side of the intercooler 22. The throttle valve 24 has an idle switch 26 that is “ON” (LL “ON”) when the throttle valve is fully closed, and the opening of the throttle valve 24. Is for example 40
The power switch 28 that turns on (PSW "on") when [%] or more is attached is installed. A surge tank 30 is formed downstream of the throttle valve 24, and an intake manifold 32 and an intake port 34 are provided downstream of the surge tank 30. A fuel injection valve 36 that opens according to a valve opening signal from the engine controller 12 is attached to the intake port 34. An exhaust manifold 40 is provided on the downstream side of a combustion chamber 38 that burns the fuel injected from the fuel injection valve 36. The exhaust manifold 40 is equipped with an O ₂ sensor 42 that detects the residual oxygen concentration of the exhaust gas and outputs an air-fuel ratio signal.

The engine block 44 that forms the combustion chamber 38 is provided with an engine water temperature sensor 46 that detects the cooling water temperature in the water jacket and outputs a cooling water temperature signal, and a knock sensor 47 that detects vibration and outputs knock vibration. ing.

A high voltage from an igniter 50 whose ignition timing is controlled according to an output from the engine controller 12 is supplied to a spark plug 48 provided in the combustion chamber 38 via a distributor 52. The distributor 52 is provided with an engine speed sensor 54 that detects the engine speed Ne and outputs an engine speed signal, and a cylinder discrimination sensor 56 that outputs a cylinder discrimination signal.

An exhaust turbine 60 of the turbocharger 18, which is driven by exhaust gas, is arranged downstream of the exhaust manifold 40. Also, bypass the exhaust turbine 60,
Further, a bypass passage 62 is provided so as to connect the upstream side and the downstream side of the exhaust turbine. A wastegate valve 64 is provided in the bypass path 62, and the open state of the wastegate valve 64 is controlled by an actuator 66. The intake pipe pressure downstream of the compressor 20 of the turbocharger 18 is introduced into the actuator 66, and the introduction path 68 is provided with a solenoid valve 70. The solenoid valve 70 is turned on and off by the engine controller 12, and when in the “on” state,
The introduction path 68 is squeezed into the atmosphere for communication. Therefore, the waste gate valve 64 opens in response to the increase in the boost pressure,
The turbo select switch 72 is set to the "LO mode" depending on the state of the solenoid valve 70 that is opened / closed according to the output from the engine controller 12 while controlling the amount of exhaust gas flowing into the exhaust turbine 60 to limit the upper limit of the boost pressure. , The supercharging pressure upper limit is lower (here, 280 mmH
g), and when the turbo select switch 72 is set to the “normal mode”, the upper limit of the supercharging pressure is controlled to a higher supercharging pressure (here, 520 mmHg).

The engine controller 12 includes an input / output interface 74,
The storage unit 76 and the central processing unit 78 are provided to perform the following processing.

(1) Input / output interface for signals from sensors and switches provided in the engine 10 and various parts of the vehicle
The process of entering through 74.

(2) Based on the various signals input above, the storage unit 76
A process of calculating various drive signals in the central processing unit 78 according to the programs of the knocking control routine shown in FIG.

(3) Based on the calculation result of the central processing unit 78, the engine
A process of outputting a drive signal and the like of each unit of 10 from the input / output interface 74.

Next, the knocking control routine of this embodiment, which is executed by the engine controller 12 at each end of each ignition cycle, will be described with reference to the flowchart of FIG. When this knocking control routine is started, first the intake air amount sensor 17
Load change amount calculated based on the intake air amount Q detected by
It is determined whether or not ΔQ / N | exceeds a predetermined value A (step 100). If it is determined that the load change amount | ΔQ / N | is less than or equal to the predetermined value A, then the engine speed sensor 54
It is determined whether or not the rotational speed change amount | ΔNe | calculated based on the detected engine rotational speed Ne exceeds the predetermined value B (step 110). Here, when it is determined that the rotation speed change amount | ΔNe | is less than or equal to the predetermined value B, that is, when the engine operating state is not during transient operation (hereinafter, referred to as steady state),
Next, the averaged value Vmeane in the steady state is calculated based on the above-mentioned equation (1) (step 120). That is, first, the averaging value Vm calculated by integrating the value of each waveform peak which is the output value of the knock sensor 47 for one ignition and the previous averaging value Vmean are substituted into the equation (1), and this time Smoothing value V
Calculate mean.

Next, the judgment level Vref is calculated based on the above-mentioned equation (2) (step 130). That is, the smoothed value V
A determination level Vref that is a reference for knocking determination is calculated based on mean.

On the other hand, judgment during the transient operation (step 100 or 110)
If the load change amount | ΔQ / N | exceeds the predetermined value A, the rotation speed change amount | ΔNe |
When it is determined that the engine 10 is in the transient operation state, the smoothing value Vmean at the time of the transient is reduced as compared with the equation (1), and the smoothing coefficient is set to the following (3). ) Equation () is calculated (step 140).

Vmean ← Vmean × 7/8 + Vm × 1/8 (3) Next, the determination level Vref is calculated in the same manner as in the steady state by the above-described step 130.

Through the above steps 100 to 140, the operating state of the engine is reflected in the determination level Vref that is the reference for knocking determination.

Following the calculation of the determination level Vref, next, by determining whether or not the current peak hold value Va of the knock sensor 47, that is, the maximum value of the output value of the knock sensor at one ignition, is larger than the determination level Vref. , It is determined whether knocking has occurred (step 150). If it is determined that the peak hold value Va is larger than the determination level Vref, that is, if knocking has occurred, then the ignition timing is delayed (step 160). That is, the ignition timing is actually retarded by a known ignition timing control routine by performing a process of subtracting a predetermined value from the advance value. This retard of ignition timing reduces knocking.

On the other hand, when the peak hold value Va is equal to or lower than the determination level Vref, that is, when knocking does not occur, the ignition timing is advanced next to actually advance the ignition timing (step 170). ).

If knocking occurs again as a result of repeating the process for advancing the angle of advance, the ignition timing is delayed again in step 160 described above. Therefore, the ignition timing of the engine 10 can always be feedback-controlled to a value at which the maximum torque is generated. Also, in this embodiment,
In addition to reducing the occurrence of knocking by delaying the ignition timing, control is also performed to reduce the boost pressure of the engine 10. This prevents an excessive retardation.

As described above, in the present embodiment, when the operating state of the engine 10 is in transition, when the determination level Vref that is the reference for determining knocking is calculated, the ratio of the current output value of the knock sensor 47 is increased. As a result, it becomes possible to accurately determine the knocking of the engine, and as a result, there is an extremely excellent effect that the engine can always be burned in an optimum state.

That is, by reflecting the transient state of the engine on the value of the judgment level Vref, when the output value of the knock sensor greatly changes even when knocking does not occur, the judgment level Vref is compared with the output value of the knock sensor in the steady state. Can be followed in a state closer to the change of. As a result, the determination level Vref follows the operating state of the engine during transition and becomes accurate, so that the knocking determination becomes accurate.

In addition, by increasing the steadiness coefficient in the steady state as compared with the conventional case, it is possible to eliminate the influence of variations in combustion and electric noise.

The present invention is not limited to the above embodiment,
Various aspects can be implemented without changing the gist.

[Effects of the Invention] The knocking detection device of the present invention detects a transient operating state of the engine in which the output value of the knock sensor fluctuates greatly even if knocking does not occur, and at the time of the transition, the determination level is set to the output value of the knock sensor. By following the fluctuation of 1 in a state closer to that in the steady state, it is possible to accurately determine the occurrence of knocking, which is an extremely excellent effect. That is, during transient operation, the output of the knock sensor during the current transient operation is largely reflected in the knocking determination level, so that when the knock sensor output value fluctuates significantly even when knocking does not occur, the determination level is increased. It is possible to follow changes in the output value of the knock sensor. As a result, when knocking actually occurs, the knocking can be determined accurately and with high accuracy.
That is, the present invention improves the responsiveness and accuracy during transient operation. In addition, since the averaging coefficient can be increased in the steady state, the effect of combustion variation and electric noise can be largely eliminated.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a basic configuration of a knocking detection device of the present invention, FIG. 2 is a configuration diagram of an engine of an embodiment to which the present invention is applied, and FIG. 3 is a knocking control routine of the embodiment. The flowcharts shown in FIGS. 4 and 5 are explanatory views of a conventional example. MA ... Engine, MB ... Knock sensor MC ... Judgment level calculation means MD ... Knocking judgment means ME ... Transient operation detection means MF ... Transient correction means 10 ... Engine, 12 ... Engine controller 17 ... Intake air quantity sensor, 47 ... Knock sensor 54 ... Engine speed sensor

Claims (1)

[Scope of utility model registration request] 1. A knock sensor for detecting engine vibration and a predetermined smoothing coefficient for determining a weighting ratio of a weighted average value are used to smooth the output of the knock sensor for each ignition to obtain a background value. A determination level calculating means for calculating the knocking determination level using this background value, and a knocking determination means for comparing the knocking determination level with the output of the knock sensor to determine the occurrence of knocking, In a knocking detection device comprising: a transient operation detection means for detecting an operating state of the engine to detect a transient operation of the engine; and a smoothing coefficient of the determination level calculation means for the transient operation. Adjust to a smaller value to increase the ratio of the latest output of the knock sensor to the background value. Knocking detecting apparatus characterized by comprising: a time correction unit operation, the.